Probiotics enhance alveolar bone microarchitecture, intestinal morphology and estradiol levels in osteoporotic animals

BACKGROUND AND OBJECTIVE

Osteoporosis is associated with bone microarchitecture alterations, and the depletion of estrogen during menopause is a major contributing factor to its development. The literature highlights the noteworthy role of gut microbiota in bone metabolism, particularly in the progression of osteoporosis. Periodontal disease leads to alveolar bone loss, which may be influenced by estrogen deficiency, and this mechanism is intricately associated with an imbalance in systemic microbiota. The aim of this study was to evaluate the effects of Bifidobacterium animalis subsp. lactis HN019 (B. lactis HN019) and Lacticaseibacillus casei 01 (L. casei 01) administrations on an osteoporosis animal model.

MATERIALS AND METHODS

Thirty-three female rats were randomly divided into three groups: control (C-OVX), C-OVX-HN019 and C-OVX-LC01. All animals were ovariectomized. In groups C-OVX-HN019 and C-OVX-LC01, the probiotics were administered for 4 months. All animals were euthanized after 16 weeks from ovariectomy. Microtomographic, histopathological and immunohistochemical examinations were conducted on periodontal tissues, whereas histomorphometry, histopathological and immunohistochemical analyses were carried out on the intestine. The levels of estradiol were assessed in blood using an immunoenzymatic assay. The data were subjected to statistical analyses (p < .05).

RESULTS

The C-OVX-LC01 group exhibited a significant reduction in alveolar bone porosity and an increase in connective tissue density compared to C-OVX (p < .05). The C-OVX-HN019 and C-OVX-LC01 groups presented reduced expression of TRAP and RANKL compared to the C-OVX (p < .05). The C-OVX group presented villi defects, mild neutrophil infiltration, decrease in both villous height and intestinal crypts and reduced expression of intestinal junctional epithelium markers e-cadherin and claudin 01 compared to C-OVX-HN019 and C-OVX-LC01 (p < .05). The C-OVX group had lower estradiol levels than C-OVX-HN019 and C-OVX-LC01 (p < .05).

CONCLUSION

The probiotic therapy promoted a reduction in alveolar bone destruction and intestinal permeability as well as an increase in estradiol levels in ovariectomized rats. Specifically, the probiotic strain Lacticaseibacillus casei 01 exhibited greater effectiveness compared to Bifidobacterium animalis subsp. lactis HN019, indicating strain-dependent outcomes.

Evaluation of Bone Growth around Autotransplanted Teeth Using Cone-Beam Computed Tomographic Images

INTRODUCTION

The aim of this observational study was to evaluate bone growth at the recipient site of autotransplanted teeth using cone-beam computed tomography (CBCT) images and to compare it to the control tooth.

METHODS

Bone growth was measured on CBCT images obtained from the anterior region of the maxilla, which received a single transplant of immature premolars due to early loss of the central incisor. The results were compared to the bone growth of contralateral central incisor that served as control. The sample consisted of 13 autotransplanted teeth and 13 control teeth. It was determined the thickness of the buccal bone of the marginal ridge, the thickness of the palatal bone of the marginal ridge, the height of the maxillary bone, and the thickness of the maxillary bone at its mid-height. The measurements were analyzed statistically, adopting a significance level of 5%.

RESULTS

The mean interval between the dental autotransplantation surgery and the CBCT scan was 16.2 years. The mean thickness of the buccal bone of the marginal ridge, thickness of the palatal bone of the marginal ridge, height of the maxillary bone, and thickness of the maxillary bone at its mid-height were, respectively, 0.85, 0.94, 19.6, and 8.85 mm for autotransplanted teeth and 0.79, 1.09, 18.88, and 8.5 mm for control teeth. There were no significant differences in the bone measurements between autotransplanted and control teeth (P > .05).

CONCLUSIONS

The growth of maxillary bone in the region that received the autotransplanted tooth was proportional to that of maxillary bone that supports the contralateral tooth. Thus, autogenous transplantation is efficient in maintaining the bone architecture at the recipient site.

Physical training mitigates alveolar bone and blood enzymatic antioxidants defense impairment induced by binge ethanol consumption in rats

We aimed to investigate the effectiveness of physical training as a protective strategy to mitigate alveolar bone damage and blood antioxidant defense caused by ethanol (EtOH) consumption in a binge-drinking pattern. Male Wistar rats aged approximately 90 days were divided into four groups: control, training, EtOH, and training + EtOH. The physical training protocol was conducted on a treadmill for four consecutive weeks, while the animals in the EtOH group were administered EtOH via orogastric gavage for three consecutive days each week, following the binge drink pattern. After the training period, blood and mandibles were collected for plasma oxidative biochemistry analysis, and the alveolar bone was subjected to physicochemical composition analysis, tissue evaluation, and microtomography evaluation. Our results showed that EtOH induced oxidative stress and physical exercise promoted the recovery of antioxidant action. Physical training minimized the damage to the mineral/matrix composition of the alveolar bone due to EtOH consumption and increased the density of osteocytes in the trained group treated with EtOH than in those exposed only to EtOH. Furthermore, physical training reduced damage to the alveolar bone caused by EtOH consumption. Our findings suggest that physical training can serve as an effective strategy to reduce systemic enzymatic oxidative response damage and alleviate alveolar bone damage resulting from alcohol consumption. Further investigations are warranted to elucidate the underlying mechanisms and explore, in addition to physical training, the potential effects of other activities with varying intensities on managing alcohol-induced bone damage.

Alveolar bone retention following treatment of dilacerated labial inversely impacted maxillary central incisors-a retrospective study

The root of late-dental-age labial inversely impacted maxillary central incisors (LIIMCIs) typically develops to severe dilacerated morphology. Therefore, reliable posttreatment periodontal estimates of orthodontic treatment prognosis would be critical to the treatment value of impacted incisors. This study aims to analyze further changes in dimensions of the alveolar bone following the closed-eruption treatment of late-dental-age dilacerated LIIMCIs. Cone beam computed tomography (CBCT) scanning data of 16 patients with unilateral dilacerated late-dental-age LIIMCIs were collected, including the pretreatment (T1) and at the 2.23 ± 0.78 years follow-up stage (T2) respectively. Patients underwent closed-eruption treatments to bring the impacted incisor into the dental arch. Dolphin imaging software was used to measure alveolar bone height labially, palatally, and proximally to the site at T1 and T2, as well as alveolar bone thicknesses at 0, 2, 4, 6 and 8 mm below the initial measurement plane (IMP). The alveolar bone heights on the impacted and contralateral sides increased from T1 to T2 (p < 0.05). Alveolar bone growth on both sides had no significant difference. In T2, the mean values of labial and distal alveolar heights on the contralateral sides were greater than on the impacted sides (p < 0.05). The mean values of total alveolar bone thicknesses on the impacted sides in T1 were significantly smaller than those on the contralateral sides in IMP-0, 2, 4, 6, 8 (p < 0.05). The total thicknesses on the impacted sides in T2 increased and were significantly greater than on the contralateral sides (p < 0.05), except for the thickness in IMP-0. The closed-eruption treatment of dilacerated late-dental-age LIIMCIs results in no significant changes to alveolar bone height, except on the labial and distal sides, with increased alveolar bone thickness, suggesting that this approach may be viable first choice therapy for non-extraction orthodontic cases.

Cone-beam computed tomographic evaluation of mandibular incisor alveolar bone changes for the intrusion arch technique: A retrospective cohort research

Objective

: Alveolar bone loss is a common adverse effect of intrusion treatment. Mandibular incisors are prone to dehiscence and fenestrations as they suffer from thinner alveolar bone thickness.

Methods

: Thirty skeletal class II patients treated with mandibular intrusion arch therapy were included in this study. Lateral cephalograms and cone-beam computed tomography images were taken before treatment (T1) and immediately after intrusion arch removal (T2) to evaluate the tooth displacement and the alveolar bone changes. Pearson's and Spearman's correlation was used to identify risk factors of alveolar bone loss during the intrusion treatment.

Results

: Deep overbite was successfully corrected (P < 0.05), accompanied by mandibular incisor proclination (P < 0.05). There were no statistically significant change in the true incisor intrusion (P > 0.05). The labial and lingual vertical alveolar bone levels showed a significant decrease (P < 0.05). The alveolar bone is thinning in the labial crestal area and lingual apical area (P < 0.05); accompanied by thickening in the labial apical area (P < 0.05). Proclined incisors, non-extraction treatment, and increased A point-nasion-B point (ANB) degree were positively correlated with alveolar bone loss.

Conclusions

: While the mandibular intrusion arch effectively corrected the deep overbite, it did cause some unwanted incisor labial tipping/flaring. During the intrusion treatment, the alveolar bone underwent corresponding changes, which was thinning in the labial crestal area and thickening in the labial apical area vice versa. And increased axis change of incisors, non-extraction treatment, and increased ANB were identified as risk factors for alveolar bone loss in patients with mandibular intrusion therapy.

[Research Progress in the Molecular Regulatory Mechanisms of Alveolar Bone Restoration]

Alveolar bone, the protruding portion of the maxilla and the mandible that surrounds the roots of teeth, plays an important role in tooth development, eruption, and masticatory performance. In oral inflammatory diseases, including apical periodontitis, periodontitis, and peri-implantitis, alveolar bone defects cause the loosening or loss of teeth, impair the masticatory function, and endanger the physical and mental health of patients. However, alveolar bone restoration is confronted with great clinical challenges due to the the complicated effect of the biological, mechanical, and chemical factors in the oral microenvironment. An in-depth understanding of the underlying molecular regulatory mechanisms will contribute to the exploration of new targets for alveolar bone restoration. Recent studies have shown that Notch, Wnt, Toll-like receptor (TLR), and nuclear factor-κB (NF-κB) signaling pathways regulate the proliferation, differentiation, apoptosis, and autophagy of osteoclasts, osteoblasts, osteocytes, periodontal ligament cells, macrophages, and adaptive immune cells, modulate the expression of inflammatory mediators, affect the balance of the receptor activator for nuclear factor-κB ligand/receptor activator for nuclear factor-κB/osteoprotegerin (RANKL/RANK/OPG) system, and ultimately participate in alveolar bone restoration. Additionally, alveolar bone restoration involves AMP-activated protein kinase (AMPK), phosphatidyl inositol 3-kinase/protein kinase B (PI3K/AKT), Hippo/YAP, Janus kinase/signal transducer and activator of transcription (JAK/STAT), and transforming growth factor β (TGF-β) signaling pathways. However, current studies have failed to construct mature molecular regulatory networks for alveolar bone restoration. There is an urgent need for further research on the molecular regulatory mechanisms of alveolar bone restoration by using new technologies such as single-cell transcriptome sequencing and spatial transcriptome sequencing.

Postmenopausal women with HIV have increased tooth loss

BACKGROUND

With effective antiretroviral therapy, people with HIV (PWH) are living longer and aging; the majority of PWH in the United States are now over the age of 50 and in women have gone through the menopause transition. Menopause potentiates skeletal bone loss at the spine, hip, and radius in PWH. The alveolar bone which surronds the teeth is different than long bones because it is derived from the neural crest. However, few studies have assessed the oral health and alveolar bone in middle aged and older women with HIV. Therefore, the objective of this study was to evaluate periodontal disease and alveolar bone microarchitecture in postmenopausal women with HIV.

METHODS

135 self-reported postmenopausal women were recruited (59 HIV-, 76 HIV + on combination antiretroviral therapy with virological suppression) from a single academic center. The following parameters were measured: cytokine levels (IFN-γ, TNF-α, IL-1β, IL-2, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12p70, IL-13, IL-17 A, OPG, and RANKL) in gingival crevicular fluid, bleeding on probing, probing depth, clinical attachment loss, number of teeth present, alveolar crestal height, and alveolar bone microarchitecture.

RESULTS

The mean age of participants was 57.04+/-6.25 years and a greater proportion of women with HIV were black/African American (HIV + 68.42%, HIV- 23.73%; p < 0.001). There was no significant difference in bleeding on probing (p = 0.17) and attachment loss (p = 0.39) between women who were HIV infected vs. HIV uninfected. Women with HIV had significantly higher RANKL expression in Gingival Crevicular Fluid (HIV + 3.80+/-3.19 pg/ul, HIV- 1.29+/-2.14 pg/ul ; p < 0.001), fewer teeth present (HIV + 17.75+/-7.62, HIV- 22.79+/-5.70; p < 0.001), ), lower trabecular number (HIV + 0.08+/-0.01, HIV- 0.09+/-0.02; p = 0.004) and greater trabecular separation (HIV + 9.23+/-3.11, HIV- 7.99+/-3.23; p = 0.04) compared to women without HIV that remained significant in multivariate logistic regression analysis in a sub-cohort after adjusting for age, race/ethnicity, smoking status, and diabetes.

CONCLUSION

Postmenopausal women with HIV have deterioration of the alveolar trabecular bone microarchitecture that may contribute to greater tooth loss.

Comparison of mandibular buccal shelf morphology between adolescents and adults with different vertical patterns using CBCT

OBJECTIVE

This retrospective study aimed to analyze the anatomical structure of the mandibular buccal shelf (MBS) in adolescents and adults with different vertical patterns to determine the optimal location for miniscrew insertion in orthodontic treatment.

METHODS

Cone-beam computed tomography (CBCT) scans of 230 patients were utilized for measurements. The morphology and thickness of alveolar bone at the MBS were measured. Two-way ANOVA and regression analysis were conducted to analyze the influencing factors on alveolar bone and cortical bone thickness.

RESULTS

Age had a significant effect on alveolar bone thickness (level I: F = 62.449, level II: F = 18.86, p < 0.001), cortical bone thickness (level II: F = 18.86, p < 0.001), alveolar bone tilt (F = 6.267, p = 0.013), and second molar tilt (F = 6.693, p = 0.01). Different vertical patterns also influenced alveolar bone thickness (level I: F = 20.950, level II: F = 28.470, p < 0.001), cortical bone thickness (level I: F = 23.911, level II: F = 23.370, p < 0.001), and alveolar bone tilt (F = 27.046, p < 0.001). As age increased, the alveolar bone thickness at level I decreased by 0.096 mm and at level II decreased by 0.073 mm. Conversely, the thickness of alveolar bone at level I and level II increased by 0.06 mm and 0.075 mm, respectively. The cortical bone thickness at level I and level II increased by 0.024 mm and 0.29 mm, respectively. However, the alveolar bone thickness decreased by 0.931 mm and 1.545 mm at level I and level II, and the cortical bone thickness decreased by 0.542 mm and 0.640 mm at level I and level II, respectively.

CONCLUSION

Age, different vertical patterns, alveolar bone inclination, and different shapes of MBS significantly affected the thickness of alveolar bone and cortical bone in the MBS area. Notably, only alveolar bone thickness and cortical bone thickness at level II were affected by age and different vertical patterns simultaneously. These findings can provide valuable insights for orthodontic practitioners in selecting the most suitable location for miniscrew insertion during treatment planning.

The impact of immediate versus delayed mini-screw placement on alveolar bone preservation and bone density following tooth extraction: evidence from a canine model

The aim of this study was to evaluate the impact of mini-screw placement on the alveolar ridge using a split-mouth design. Twelve beagles underwent bilateral extraction of their lateral teeth. In the immediate group, a mini-screw was unilaterally placed approximately 3-4 mm below the alveolar crest of the extraction site on the experimental side. The delayed group received mini-screws six weeks after tooth extraction. On average, the dogs were sacrificed after 11 weeks, and the maxillary bones were excised and scanned using cone-beam computed tomography (CBCT). Histopathological examinations were conducted to assess inflammation and bone formation scores. The results showed that in the immediate group, bone height was significantly greater on the intervention side compared to the control side (p < 0.05), whereas there was no significant difference in the delayed group. In both groups, there was a significant increase in bone density around the mini-screws compared to the control sides (p < 0.05). Mini-screw insertion led to a significant enhancement of bone growth in both groups (p < 0.05), with no notable differences between the two groups. The mini-screws did not have any impact on bone inflammation or width. Overall, both immediate and delayed mini-screw placement in the extraction socket positively influenced bone dimensions, density, and histological properties. However, immediate insertion was more effective than delayed placement in preserving vertical bone height, despite delayed insertion resulting in higher bone density.

Effects of different doses of ionizing radiation on alveolar bone repair in post-extraction tooth socket: an experimental study in rats

OBJECTIVE

This study aimed to evaluate the dose-response effects of ionizing radiation (IR) on alveolar bone repair and bone strength after tooth extraction.

MATERIALS AND METHODS

A total of 32 male Wistar rats were used in the study, 28 animals were included in the final analysis, and n = 7 for each experimental group. Mandibular first molars were extracted. After 7 days, the animals were randomly divided into four groups according to single-dose irradiation: NIr, control group; Ir15, irradiated at 15 Gy; Ir20, irradiated at 20 Gy; and Ir30, irradiated at 30 Gy. The tooth extraction sites were subjected to micro-computed tomography (micro-CT), histological, histomorphometric, and biomechanical analyses 14 days after extraction. Data were analyzed using one-way ANOVA followed by Tukey's post hoc test (α = 0.05).

RESULTS

Micro-CT analysis revealed that IR led to lower values of bone volume (BV, in mm3) (0.68 ± 0.08, P < 0.001) and bone volume fraction, ratio of the segmented bone volume to the total volume of the region of interest (BV/TV, in %) (44.1 ± 8.3, P < 0.001) for the Ir30 group compared to the control group. A significantly lower amount of newly formed bone was observed in the Ir30 (P = 0.005) than in the Ir15 group. The histomorphometric results of quantification of bone matrix neoformation and the micro-CT were in agreement, demonstrating greater damage to the Ir30 group. IR30 cells showed a lower percentage of densely packed collagen than control cells. No significant differences were found in the biomechanical parameters.

CONCLUSION

IR affects alveolar bone repair. A dose of 30 Gy reduced the bone healing process owing to a smaller amount of newly formed bone and a lower percentage of densely packed collagen. Therefore, a dose of 30 Gy can be used to successfully establish an animal model of an irradiated mandible that mimics the irradiated clinical conditions.

CLINICAL RELEVANCE

Radiotherapy can lead to severe side effects and tooth extraction is a major risk factor. A proper understanding of the pathological mechanisms of radiation in alveolar bone repair requires the establishment of a suitable animal model of clinical conditions.

Alveolar bone changes in the mandibular incisors after genioplasty, a three-dimensional study

INTRODUCTION

Functional genioplasty aims to achieve lip competence at rest and reduces lip pressure against the mandibular incisors. The purpose of this study was to describe the radiographic changes in alveolar bone of the mandibular incisors after functional genioplasty.

MATERIALS AND METHODS

Cone beam CT images from 36 patients were compared between immediate (T0) and delayed postoperative period (T1). The mean time to complete the second imaging was 10.9 ± 4.7 months. Dental and bone parameters were assessed: the vestibular bone height (BH), the bone thickness (BT) with regard to the apex of the central incisor (BT2) and at equidistance between the cementoenamel junction and the dental apex (BT1). The existence of fenestrations, the apical-root resorption and the incisor-mandibular plane angle (IMPA) were also collected.

RESULTS

No significant change occurred in the BH. BT was improved of a mean 47.9% and 53.6% at the BT1 level on #31 and #41, respectively (p1=0.01 and p2=0.02, respectively); and of 53.0% at the level of the apex of both mandibular central incisors (p1=0.003 on #31 and p2=0.009 on #41). No difference in the number of fenestrations was observed between T0 and T1. A significant decrease in the root length on both mandibular incisors was observed on the delayed CBCT (from 21.96 ± 1.35 to 21.68 ± 1.32 mm for #31, p=0.0007; from 22.26 ± 1.66 to 21.96 ± 1.48 mm for #41, p=0.002). Finally, the IMPA remained stable between the two examinations with a mean 106.1 ± 7.38° vs 105.8 ± 6.51° (p=0.38).

CONCLUSION

Functional genioplasty favours the alveolar bone formation of the mandibular central incisors, probably by direct bone grafting, but also by the relaxation of the perioral and chin musculature.

Quantification of the apical palatal bone index for maxillary incisor immediate implant assessment: A retrospective cross-sectional study

BACKGROUND

Apical palatal bone is important in immediate implant evaluation. Current consensus gives qualitative suggestions regarding it, limiting its clinical decision-making value.

OBJECTIVES

To quantify the apical palatal bone dimension in maxillary incisors and reveal its quantitative correlation with other implant-related hard tissue indices to give practical advice for pre-immediate implant evaluation and design.

MATERIAL AND METHODS

A retrospective analysis of immediate implant-related hard tissue indices in maxillary incisors obtained by cone beam computed tomography (CBCT) was conducted. Palatal bone thickness at the apex level (Apical-P) on the sagittal section was selected as a parameter reflecting the apical palatal bone. Its quantitative correlation with other immediate implant-related hard tissue indices was revealed. Clinical advice of pre-immediate implant assessment was given based on the quantitative classification of Apical-P and its other correlated immediate implant-related hard tissue indices.

RESULTS

Apical-P positively correlated with cervical palatal bone, whole cervical buccal-palatal bone, sagittal root angle, and basal bone width indices. while negatively correlated with apical buccal bone, cervical buccal bone, and basal bone length indices. Six quantitative categories of Apical-P are proposed. Cases with Apical-P below 4 mm had an insufficient apical bone thickness to accommodate the implant placement, while Apical-P beyond 12 mm should be cautious about the severe implant inclination. Cases with Apical-P of 4-12 mm can generally achieve satisfying immediate implant outcomes via regulating the implant inclination.

CONCLUSIONS

Quantification of the apical palatal bone index for maxillary incisor immediate implant assessment can be achieved, providing a quantitative guide for immediate implant placement in the maxillary incisor zone.

The impact of vitamin D on clinical parameters and bone turnover biomarkers in ligature-induced periodontitis: An experimental study in rats

Objectives and Background

Vitamin D has been associated with an increased risk of tooth loss and the severity of periodontal diseases. This study aimed to evaluate the effect of vitamin D on the clinical, radiographic, and serum level changes of bone turnover biomarkers in ligature-induced periodontitis.

Methods

A total of 28 rats were included in this study and divided into test groups: Vitamin D supplement (VS), Vitamin D deficient (VD), and control (CG). Ligature-induced periodontal tissue destruction was performed and kept for 21 days. Clinical attachment and radiographic changes were recorded, and serum samples were tested for Osteoprotegerin (OPG), Dickkopf-1 (DKK1), Sclerostin (SOST), and Fibroblast growth factor 23 (FGF23) on the initial and final day of the study.

Results

Groups that were made VD exhibited a more significant amount of clinical attachment loss (1.05 ± 0.50 mm) compared to the CG (0.83 ± 0.14 mm) and VS group (0.60 ± 0.13 mm), showing significant differences (p < 0.05). The radiographic alveolar bone loss amount was greater in the VD group compared to the other groups. For serum level assessment, the VD groups also exhibited a statistically significant reduction in the levels of OPG. They showed higher concentrations of DKK1, SOST, and FGF23 than other groups, with significant differences (p < 0.05).

Conclusion

The results revealed that Vitamin D may play a role in the progression of periodontal disease. It was found to affect both clinical parameters and bone turnover biomarkers, suggesting its potential impact on the disease process.

Involvement of the Notch signaling system in alveolar bone resorption

The Notch pathway is an evolutionarily preserved signaling pathway involved in a variety of vital cell functions. Additionally, it is one of the key regulators of inflammation, and controls the differentiation and function of different cells. Moreover, it was found to be involved in skeletal development and bone remodeling process. This review provides an overview of the involvement of the Notch signaling pathway in the pathogenesis of alveolar bone resorption in different forms of pathological conditions such as apical periodontitis, periodontal disease, and peri-implantitis. In vitro and in vivo evidence have confirmed the involvement of Notch signaling in alveolar bone homeostasis. Nonetheless, Notch signaling system, along with complex network of different biomolecules are involved in pathological process of bone resorption in apical periodontitis, periodontitis, and peri-implantitis. In this regard, there is a substantial interest to control the activity of this pathway in the treatment of disorders associated with its dysregulation. This review provides knowledge on Notch signaling and outlines its functions in alveolar bone homeostasis and alveolar bone resorption. Further investigations are needed to determine whether inhibition of the Notch signaling pathways might be beneficial and safe as a novel approach in the treatment of these pathological conditions.

Nifedipine attenuates alveolar bone destruction and improves trabecular microarchitectures in mice with experimental periodontitis

Studies have shown that nifedipine exerts anti-inflammatory and immunosuppressive actions in addition to being a calcium channel blocker. The present study was performed to explore the influence of nifedipine on alveolar bone destruction in mice with experimental periodontitis by evaluating morphological information acquired from micro-computed tomography analysis. BALB/c mice were randomly assigned into four groups: control (C) group; experimental periodontitis (E) group; experimental periodontitis + 10 mg/kg dose of nifedipine (EN10) group; and experimental periodontitis + 50 mg/kg dose of nifedipine (EN50) group. Periodontitis was induced by oral inoculation with Porphyromonas gingivalis over a 3-week time period. Nifedipine significantly mitigated the loss of alveolar bone height as well as increase of root surface exposure induced by experimental periodontitis. Additionally, the reduction in the bone volume fraction associated with P. gingivalis infection was significantly recovered upon nifedipine treatment. Further, nifedipine attenuated P. gingivalis-induced deteriorations in the trabeculae-associated parameters. Significant difference was evident between Groups EN10 and EN50 in both the extent of alveolar bone loss and microstructural parameters assessed, except trabecular separation and trabecular number. Nifedipine appeared to have good performance in ameliorating bone loss in mice with induced periodontitis. Nifedipine may be utilized in the clinical management of periodontitis, though further research is indicated to verify the therapeutic effect.

Mandibular alveolar bone thickness in untreated Class I subjects with different vertical skeletal patterns: a cone-beam computed tomography study

OBJECTIVE

To evaluate the mandibular alveolar bone thickness in untreated skeletal Class I subjects with different vertical skeletal patterns.

MATERIALS AND METHODS

A total of 50 preorthodontic treatment cone-beam computed tomography (CBCT) images of a skeletal Class I Chinese population with near-normal occlusion were selected. The buccal and lingual alveolar bone thicknesses of mandibular canines to second molars were measured at 2 mm below the cementoenamel junction (CEJ), mid-root, and root apex levels. Differences in the measurements were analyzed with Mann-Whitney U-test. The correlation between alveolar bone thickness and the sella-nasion-mandibular plane (SN-MP) angle was calculated using Pearson correlation coefficients and linear regression analysis.

RESULTS

Buccal alveolar bone was thinner on all mandibular canines to first molars but thicker on second molars in comparison with lingual alveolar bone. Buccal alveolar bone was within 1 mm at the levels of 2 mm below CEJ and mid-root for the canines and first premolars. Significant differences were detected among subjects with different vertical patterns, with a negative correlation between the SN-MP angle and alveolar thickness, especially in the canine and premolar regions. The thinnest buccal and lingual alveolar bone were detected in the high-angle group canine region (0.50 mm at the levels of 2 mm below CEJ and mid-root for the buccal side, 0.90 mm at the level of 2 mm below the CEJ for the lingual side).

CONCLUSIONS

To avoid periodontal complications, buccal-lingual movement of the mandibular canines and first premolars should be limited, especially in high-angle patients.

Characteristics of mandibular anterior alveolar bone in patients with different degrees of periodontitis: a retrospective study based on CBCT

OBJECTIVES

To investigate the alveolar bone characteristics of mandibular anterior teeth in patients with periodontitis.

MATERIALS AND METHODS

100 patients with periodontitis were selected and grouped according to the degrees of alveolar bone resorption, age, gender, and tooth type. The labial thickness of the alveolar bone, the degree of alveolar bone resorption, angulation between the long axis of teeth and alveolar process, alveolar bone height and density of the mandibular anterior teeth were measured.

RESULTS

There were significant differences in alveolar bone morphology between these three groups. Compared with the mild and moderate groups, the severe group showed that the alveolar bone in the half of the root crown was thickened, the alveolar bone height was decreased, the cancellous alveolar bone density was increased, and the cortical alveolar bone density was decreased. The resorption of alveolar bone was characterized by greater resorption of proximal bone than that of labial bone with increased bone loss. There were also differences in alveolar bone characteristics among patients of different ages, genders, and tooth types.

CONCLUSIONS

The morphology of the mandibular anterior alveolar bone changed accordingly with the degree of periodontitis. Labial alveolar bone thickness and cortical alveolar bone density were negatively correlated with the degree of periodontitis, while alveolar bone height and cancellous alveolar bone density were positively correlated with the degree of periodontitis.

CLINICAL RELEVANCE

These results allow clinicians to better understand the alveolar bone morphology of the mandibular anterior teeth in patients with periodontitis, facilitating better treatment design and avoiding complications.

Three-dimensional morphologic analysis of the maxillary alveolar bone after anterior tooth retraction with temporary anchorage devices

OBJECTIVES

To investigate three-dimensional (3D) morphologic changes in the alveolar bone around the maxillary central incisors of patients who underwent premolar extraction and subsequent anterior tooth retraction using temporary anchorage devices (TADs).

MATERIALS AND METHODS

The subjects consisted of 16 patients with bimaxillary protrusion. The maxillary anterior teeth were retracted using sliding or loop mechanics and TADs for anchorage reinforcement. Cephalograms and computed tomography scans taken pretreatment and posttreatment were registered with respect to the palatal structures. The movement of the maxillary central incisors and morphologic changes in the anterior alveolar bone were evaluated quantitatively.

RESULTS

Displacement in the palatal direction was observed in the alveolar bone around the incisors and the interdental septum. The displacement and bone remodeling/tooth movement ratio were larger on the labial side than the palatal side, and decreased progressively from the crest to apex level. The bone thickness was significantly increased on the labial side and decreased on the palatal side.

CONCLUSIONS

Regional differences exist in morphologic changes of the alveolar bone during anterior tooth retraction using TADs. Attention should be paid to the crest region of the palatal alveolar bone because of its small original thickness and low remodeling activity.

Regeneration processes of alveolar bone and microvascular changes after the application of platelet-rich fibrin

OBJECTIVES

Platelet-rich fibrin (PRF) is a promising agent for bone regeneration (BR). Platelets contain several growth factors that promote angiogenesis and BR. In this study, we observed the morphology of alveolar BR.

METHODS

PRF (Advanced PRF: A-PRF) was prepared by extracting 10 mL of blood from each dog in a collection tube before tooth extraction. The samples were centrifuged at 200 × g for 8 min and incubated for 10 min to allow clotting. The alveolar socket on the dentition's right side was densely filled with PRF. The opposite side, which did not receive PRF, served as the control group. Different methods were used for specimen preparation and observation. Sections stained with hematoxylin and eosin were observed under a light microscope. Bone specimens were observed using stereoscopic microscopy. The resin cast models were examined using a scanning electron microscope. Moreover, bone formation ratio and height were measured.

RESULTS

Fourteen days postoperatively, angiogenesis and bone deposition were more advanced in the PRF group than in the control group. Thirty days postoperatively, both groups developed porous bone. In the PRF group, new bone trabeculae (BT) and a network of blood vessels were formed in the bone marrow. Ninety days postoperatively, the resin cast showed a normal bone structure with BT and bone marrow. Thick BT were observed in the PRF group.

CONCLUSIONS

Growth factors in PRF stimulate microcirculation and promote angiogenesis and bone deposition. The benefits of PRF include safety and increased bone formation.

Generated heat at implant site during gradual and single-drill protocols among Indian patients

Excessive heat generation during bone drilling for dental implant placement is a known risk factor for bone necrosis and delayed healing. Therefore, it is of interest to evaluate the maximum change in temperature during and after preparation of the implant site for an implant diameter of 4.2 using gradual drilling and single drilling protocols. Hence, 26 artificial bone blocks with d1 density were divided into two groups where the group I had 13 sites prepared using a single drill and for group II bone blocks, 13 implant sites were prepared with the gradual drill protocol using 5 drills. The drill was done at room temperature with 1500 rpm using constant saline irrigation of 50ml/min. The maximum change in temperature was assessed using an intraoral camera. The data collected were statistically evaluated and results were formulated. Data shows that temperature change was significantly higher in group II where a gradual drill protocol was done compared to group I with a single drill protocol for placing the dental implant of diameter 4.2.Considering its limitations, the present in-vitro assessment concludes that a single drill protocol for preparing an osteotomy site for placing a dental implant of diameter 4.2 generates lesser heat than conventional gradual drilling protocols.

Three-dimensional evaluation of alveolar bone and pharyngeal airway dimensions after mandibular dentition distalization in patients with Class III malocclusion: a retrospective study

BACKGROUND

To three-dimensionally evaluate changes of the alveolar bone around the mandibular anterior teeth and pharyngeal airway dimensions in adults with Class III malocclusion before and after orthodontic treatment of mandibular dentition distalization.

METHODS

In this retrospective study, cone-beam computed tomography (CBCT) scans of 20 patients with Class III malocclusion who underwent mandibular dentition distalization were obtained both before and after treatment. Three-dimensional changes of the thickness and vertical marginal bone levels around mandibular incisors and canines were assessed and compared. And airway volumes of the palato-, glosso-, laryngopharynx and the minimum axial area were measured and compared before and after treatment.

RESULTS

A significant decrease of lingual bone thickness of mandibular incisors, partial labial and lingual bone thickness of canines were observed (P < 0.05). The reduction in root length of incisors and canines, labial and lingual vertical marginal bone levels were significant after orthodontic treatment. No significant correlations between mandibular dentition distalization and pharyngeal airway dimensions were observed.

CONCLUSIONS

Mandibular dentition distalization could result in the loss of alveolar bone around anterior teeth in Class III malocclusion, especially for the cervical marginal bone. Pharyngeal airway dimensions were not affected to a high extent after distalization.

TRIAL REGISTRATION

Retrospctively registered.

Dual stimulus responsive borosilicate glass (BSG) scaffolds promote diabetic alveolar bone defectsrepair by modulating macrophage phenotype

The regeneration of alveolar bone is still clinical challenge, particularly accompanied with diabetes, causing metabolic disorder with a protracted low-grade inflammatory phenotype. As a result, the anticipated loading of biomaterials is highly suspicious in spontaneous modulation of cells function, which is mostly disturbed by constant inflammation. In this study, we developed glucose and hydrogen peroxide dual-responsive borosilicate glass (BSG) scaffolds loaded with epigallocatechin gallate (EGCG) to synergistically modulate the abnormal inflammation of diabetic alveolar bone defects. It was found that the release of EGCG by BSG could directly regulate the shift of macrophages from M1 to the M2 phenotype by promoting autophagy and lessening the inhibition of autophagic flux. Moreover, EGCG can also indirectly regulate the polarization phenotype of macrophages by reducing the activation of NF-κb in stem cells and restoring its immunoregulatory capacity. Therefore, the addition of EGCG to BSG scaffold in diabetes allows for a more striking modulation of the macrophage phenotype in a timely manner. The altered macrophage phenotype reduces local inflammation and thus increases the ability to repair diabetic alveolar bone, showing promise for the treatment of alveolar defect in diabetic patients.

Clinical investigation of gingival papilla recession after orthodontic treatment in adults

OBJECTIVE

To investigate the incidence, severity, susceptibility sites of gingival papillary recession (GPR) in adults after orthodontic treatment and the clinical impact of tooth extraction on GPR.

METHODS

A total of 82 adult patients were recruited and then divided into extraction and non-extraction groups according to whether the orthodontic teeth were extracted (teeth that needed to be extracted when performing orthodontic treatment). The gingival conditions of the two groups of patients before and after treatment were recorded using intraoral photos, and the incidence, severity and predilection sites of GPR after correction were investigated.

RESULTS

The results indicated that GPR occurred in 29 patients after correction, with an incidence rate of 35.4%. A total of 1648 gingival papillae were recorded among the 82 patients after correction, of which 67 exhibited atrophy, with an incidence of 4.1%. All occurrences of GPR were classified as papilla presence index 2 (PPI 2) (mild). The condition is most likely to occur in the anterior tooth area, especially in the lower incisor area. The results indicated that the incidence of GPR was substantially higher in the extraction group than in the non-extraction group, with the difference statistically significant.

CONCLUSION

Following orthodontic treatment, adult patients will have a certain proportion of mild GPR, which is more common in the anterior tooth area, especially the lower anterior tooth area.

Gingival Biotypes and its Relation to Biologic Width, Alveolar Bone Thickness, Dehiscence and Fenestration in Mandibular Anterior Region: A CBCT Analysis Study

Background

Gingival biotype and its relationship to biologic width and alveolar bone thickness may affect surgical periodontal therapy outcomes. Hence, it is vital to assess the gingival biotype prior to any of these treatments for its success.

Aim

The study aims to compare the thick and thin gingival biotype in the mandibular anterior region concerning biologic width, buccal bone thickness, prevalence and distribution of dehiscence, and fenestration in lower anterior teeth.

Materials and Methods

A total of 30 patients were selected for the study based on the inclusion and exclusion criteria. The Cone Beam Computed Tomography analysis was performed in the mandibular anterior area to assess gingival thickness (biotype), biologic width, buccal bone thickness, dehiscence, and fenestrations. The data were analyzed using SPSS version 26. An independent t-test was used to assess the relationship between the variables.

Results

Our study identified an increased biologic width in the thick gingival biotype, a higher frequency of dehiscence in the thin gingival biotype than in the thick biotype, and a greater mean alveolar bone thickness in the thick biotype group.

Conclusion

A statistical difference was not observed between the groups; however, the thick biotype showed better results than the thinner biotype for the periodontal parameters examined.

Age- and sex-related differences of periodontal bone resorption, cognitive function, and immune state in APP/PS1 murine model of Alzheimer's disease

BACKGROUND

The existence of an interconnected mechanism between cognitive disorders and periodontitis has been confirmed by mounting evidence. However, the role of age or sex differences in this mechanism has been less studied. This study aims to investigate sex and age differences in the characterization of periodontal bone tissue, immune state and cognitive function in amyloid precursor protein/presenilin 1(APP/PS1) murine model of Alzheimer's disease (AD).

METHODS

Three- and twelve-month-old male and female APP/PS1 transgenic mice and wild-type (WT) littermates were used in this study. The Morris water maze (MWM) was used to assess cognitive function. The bone microarchitecture of the posterior maxillary alveolar bone was evaluated by microcomputed tomography (micro-CT). Pathological changes in periodontal bone tissue were observed by histological chemistry. The proportions of helper T cells1 (Th1), Th2, Th17 and regulatory T cells (Tregs) in the peripheral blood mononuclear cells (PBMCs) and brain samples were assessed by flow cytometry.

RESULTS

The learning ability and spatial memory of 12-month-old APP/PS1 mice was severely damaged. The changes in cognitive function were only correlated with age and genotype, regardless of sex. The 12-month-old APP/PS1 female mice exhibited markedly periodontal bone degeneration, evidenced by the decreased bone volume/total volume (BV/TV), trabecular thickness (Tb.Th), and bone mineral density (BMD), and the increased trabecular separation (Tb.Sp). The altered periodontal bone microarchitecture was associated with genotype, age and females. The flow cytometry data showed the increased Th1 and Th17 cells and the decreased Th2 cells in the brain and PBMC samples of 12-month-old APP/PS1 mice, compared to age- and sex-matched WT mice. However, there was no statistical correlation between age or sex and this immune state.

CONCLUSIONS

Our data emphasize that age and sex are important variables to consider in evaluating periodontal bone tissue of APP/PS1 mice, and the cognitive impairment is more related to age. In addition, immune dysregulation (Th1, Th2, and Th17 cells) was found in the brain tissue and PBMCs of APP/PS1 mice, but this alteration of immune state was not statistically correlated with sex or age.

Does the "Root Removal First" strategy prevent postoperative complications in the surgical removal of impacted mandibular third molars in the Pell and Gregory class C and horizontal position? - a randomized clinical trial

OBJECTIVE

To evaluate the clinical outcomes of the "Root Removal First" strategy in the surgical removal of impacted mandibular third molar (IMTM) in the class C and horizontal position.

MATERIALS AND METHODS

A total of 274 cases were finally included in the statistics. The positions of IMTM in the horizontal position were confirmed by cone-beam computed tomography (CBCT). Cases were randomly divided into two groups: the "Root Removal First" strategy was applied in the new method (NM) group, and the conventional "Crown Removal First" strategy was executed in the traditional method (TM) group. The clinical information and relevant data upon follow-up were recorded.

RESULTS

The duration of the surgical removal and the incidence rates of lower lip paresthesia in the NM group were significantly lower than those in the TM group. The degree of mobility of the adjacent mandibular second molar (M2) in the NM group was significantly lower than that in the TM group at 30 days and 3 months post-operation. The distal and buccal probing depth of the M2, as well as the exposed root length of M2 in the NM group, were significantly lower than those in the TM group 3 months post-operation.

CONCLUSIONS

The "Root Removal First" strategy can reduce the incidence rate of inferior alveolar nerve injury and periodontal complications of the M2 in the surgical removal of IMTM in class C and horizontal position with high efficiency.

TRIAL REGISTRATION

ChiCTR2000040063.

Micro-computed tomography evaluation of the effects of orthodontic force on immature maxillary first molars and alveolar bone mineral density of Sprague-Dawley rats

Objective

To investigate changes in the immature teeth of Sprague-Dawley rats during orthodontic treatment and to explore the changes in the peri-radicular alveolar bone through micro-computed tomography (CT).

Methods

Twenty-five 26-day-old male Sprague-Dawley rats were included. The maxillary left first molar was moved mesially under a continuous force of 30 cN, and the right first molar served as the control. After orthodontic treatment for 7, 14, 21, 28, and 42 days, the root length, tooth volume, and alveolar bone mineral density (BMD) around the mesial root were measured through micro-CT.

Results

The immature teeth continued to elongate after application of orthodontic force. The root length on the force side was significantly smaller than that on the control side, whereas the differences in the volume change between both sides were not statistically significant. Alveolar bone in the coronal part of the compression and tension sides showed no difference in BMD between the experimental and control groups. The BMD of the experimental group decreased from day 14 to day 42 in the apical part of the compression side and increased from day 7 to day 42 in the apical part of the tension side. The BMD of the experimental group decreased in the root apex part on day 7.

Conclusions

The root length and volume of immature teeth showed continued development under orthodontic forces. Alveolar bone resorption was observed on the compression side, and bone formation was observed on the tension side.

Alveolar bone changes following bi-maxillary vertical molars' movements using clear aligners

OBJECTIVE

This study aimed to assess the alveolar bone changes following maxillary and mandibular molars' intrusion and extrusion movements using Clear Aligners using Cone-Beam Computed Tomography (CBCT).

MATERIALS AND METHODS

This is a retrospective clinical study in which 24 adult patients with pre-designed selection criteria and a mean age of 31.1 + 9.9 years were enrolled. The alveolar bone changes around one hundred thirty-three maxillary and mandibular molars intruded or extruded by Clear Aligners therapy were analyzed from CBCT using Invivo 6.0 software. Intra- and inter-examiner reliability analysis was performed using the intra-class correlation coefficient (ICC) and Cronbach's Alpha statistics. The paired t-test was used to analyze significant differences before and after treatment (T0-T1). The significance level was considered at P < 0.05.

RESULT

The patients were divided into two groups: extrusion (48.9%, n = 65 molars' root) and intrusion (51.1%, n = 68 molars' root) group. There was a significant decrease in the alveolar bone changes in the buccal surface of the mandibular right and left 1st molars in the extrusion group (-1.05 ± 0.97, -0.76 ± 1.12 mm, respectively) and the maxillary left 2nd molars in intrusion group (-0.42 ± 0.77 mm), and the lingual surface of intrusion of the mandibular left 1st molar (-0.64 ± 0.76 mm). Comparing the mean maxillary and mandibular changes (T0-T1) of both studied groups showed that the buccal alveolar bone changes for the left 1st and right 2nd molars showed a significant difference in extrusion and intrusion groups, respectively.

CONCLUSIONS

The buccal alveolar bone changes is considered the most affected surface following maxillary and mandibular molars' intrusion and extrusion movements using clear aligners, with mandibular molars being more affected than the maxillary ones.

Role of various pharmacologic agents in alveolar bone regeneration: A review

Alveolar bone and gingiva are components of the periodontium that house the tooth. It constantly adapts itself to the masticatory forces and position of the tooth. However, localized diseases like chronic periodontitis and certain systemic diseases destroy periodontal tissues, which include the alveolar bone. Various pharmacological agents are being explored for their pleiotropic properties to combat the destruction of alveolar bone. This review focuses on the role of pharmacological agents in alveolar bone regeneration.

Low-Intensity Pulsed Ultrasound Attenuates Periodontal Ligament Cells Apoptosis by Activating Yes-Associated Protein-Regulated Autophagy

OBJECTIVE

The goal of the work described here was to determine if low-intensity pulsed ultrasound (LIPUS) has an anti-inflammatory effect on lipopolysaccharide (LPS)-induced inflammation in periodontal ligament cells (PDLCs). The mechanism underlying this effect remains to be explored and is likely related to PDLC apoptosis regulated by Yes-associated protein (YAP) and autophagy.

METHODS

To verify this hypothesis, we used a rat model of periodontitis and primary human PDLCs. We examined alveolar bone resorption in rats and apoptosis, autophagy and YAP activity in LPS-treated PDLCs with and without application of LIPUS by cellular immunofluorescence, transmission electron microscopy and Western blotting. Then, siRNA transfection was used to decrease YAP expression to confirm the regulatory role of YAP in the anti-apoptotic effect of LIPUS on PDLCs.

DISCUSSION

We found that LIPUS attenuated alveolar bone resorption in rats and this was accompanied by YAP activation. LIPUS inhibited hPDLC apoptosis by YAP activation, and promoted autophagic degradation to help autophagy completion. These effects were reversed after YAP expression was blocked.

CONCLUSION

LIPUS attenuates PDLC apoptosis by activating Yes-associated protein-regulated autophagy.

Evaluation of cuspid cortical anchorage with different sagittal patterns using cone-beam computed tomography: a retrospective study

BACKGROUND

No studies have focused on cortical anchorage resistance in cuspids, this study aimed to characterize the cortical anchorage according to sagittal skeletal classes using cone-beam computed tomography (CBCT).

METHODS

CBCT images of 104 men and 104 women were divided into skeletal class I, II, and III malocclusion groups. Skeletal and dental evaluations were performed on the sagittal and axial cross-sections. One-way analysis of variance followed by least significant difference post-hoc tests was used for group differences. Multiple linear regression was performed to evaluate the relationship between influential factors and cuspid cortical anchorage.

RESULTS

All cuspids were close to the labial bone cortex in different sagittal skeletal patterns and had different inclinations. There was a significant difference in the apical root position of cuspids in the alveolar bone; however, no significant difference in the middle or cervical portions of the root was found between different sagittal facial patterns. The middle of the cuspid root was embedded to the greatest extent in the labial bone cortex, with no significant difference between the sagittal patterns. For all sagittal patterns, 6.03 ± 4.41° (men) and 6.08 ± 4.45° (women) may be appropriate root control angles to keep maxillary cuspids' roots detached from the labial bone cortex.

CONCLUSIONS

Comparison of skeletal class I, II, and III malocclusion patients showed that dental compensation alleviated sagittal skeletal discrepancies in the cuspid positions of all patients, regardless of the malocclusion class. Detailed treatment procedures and clear treatment boundaries of cuspids with different skeletal patterns can improve the treatment time, periodontal bone remodeling, and post-treatment long-term stability. Future studies on cuspids with different dentofacial patterns and considering cuspid morphology and periodontal condition may provide more evidence for clinical treatment.

Spontaneous spheroids from alveolar bone-derived mesenchymal stromal cells maintain pluripotency of stem cells by regulating hypoxia-inducible factors

BACKGROUND

Spontaneous spheroid culture is a novel three-dimensional (3D) culture strategy for the rapid and efficient selection of progenitor cells. The objectives of this study are to investigate the pluripotency and differentiation capability of spontaneous spheroids from alveolar bone-derived mesenchymal stromal cells (AB-MSCs); compare the advantages of spontaneous spheroids to those of mechanical spheroids; and explore the mechanisms of stemness enhancement during spheroid formation from two-dimensional (2D) cultured cells.

METHODS

AB-MSCs were isolated from the alveolar bones of C57BL/6 J mice. Spontaneous spheroids formed in low-adherence specific culture plates. The stemness, proliferation, and multi-differentiation capacities of spheroids and monolayer cultures were investigated by reverse transcription quantitative polymerase chain reaction (RT-qPCR), immunofluorescence, alkaline phosphatase (ALP) activity, and oil-red O staining. The pluripotency difference between the spontaneous and mechanical spheroids was analyzed using RT-qPCR. Hypoxia-inducible factor (HIFs) inhibition experiments were performed to explore the mechanisms of stemness maintenance in AB-MSC spheroids.

RESULTS

AB-MSCs successfully formed spontaneous spheroids after 24 h. AB-MSC spheroids were positive for MSC markers and pluripotency markers (Oct4, KLF4, Sox2, and cMyc). Spheroids showed higher Ki67 expression and lower Caspase3 expression at 24 h. Under the corresponding conditions, the spheroids were successfully differentiated into osteogenic and adipogenic lineages. AB-MSC spheroids can induce neural-like cells after neurogenic differentiation. Higher expression of osteogenic markers, adipogenic markers, and neurogenic markers (NF-M, NeuN, and GFAP) was found in spheroids than in the monolayer. Spontaneous spheroids exhibited higher stemness than mechanical spheroids did. HIF-1α and HIF-2α were remarkably upregulated in spheroids. After HIF-1/2α-specific inhibition, spheroid formation was significantly reduced. Moreover, the expression of the pluripotency genes was suppressed.

CONCLUSIONS

Spontaneous spheroids from AB-MSCs enhance stemness and pluripotency. HIF-1/2α plays an important role in the stemness regulation of spheroids. AB-MSC spheroids exhibit excellent multi-differentiation capability, which may be a potent therapy for craniomaxillofacial tissue regeneration.

Evaluation of root resorption in the lower incisors after orthodontic treatment of skeletal Class III malocclusion by three-dimensional volumetric measurement with cone-beam computed tomography

OBJECTIVES

To investigate the volumetric changes of the lower incisor roots in skeletal Class III orthodontic patients with anterior crossbite after premolar extraction therapy.

MATERIALS AND METHODS

Thirty-six adults, aged 18-28 years, had four-premolar extraction treatment. Pre- and posttreatment cone-beam computed tomography (CBCT) images were used to assess the thickness and height of alveolar bone, root volume, and length. A paired t-test was used to detect changes in root volume and length before and after treatment. Pearson's correlation analysis was applied to estimate the correlation between root volume and dentoskeletal morphology.

RESULTS

Both the central and lateral incisors had intrusion and tipping movement after treatment. Compared with pretreatment data, root length decreased significantly. The lingual root volume of root cervical, apical third, and the labial root volume of the root apical third decreased significantly (P < .05), among which the percentage of tooth loss at the tip volume was the highest. The pretreatment height of the alveolar ridge crest, thickness of the alveolar bone, and type of incisor movement were related to the volume and length loss.

CONCLUSIONS

Volume and length loss in the apical third of the lower incisor roots in skeletal Class III patients treated with a Class III bicuspid extraction pattern is common. The pretreatment height of the alveolar ridge crest, thickness of the alveolar bone, and type of tooth movement are related to the loss.

Implementation of a personal identification system using alveolar bone images

OBJECTIVE

In recent years, personal identification has been performed using antemortem panoramic X-ray images and postmortem-CT images. Using these, we have developed a personal identification method that focuses on the alveolar bone. This study examined the effectiveness of this method and aimed to implement a reproducible system.

MATERIALS AND METHODS

For personal identification, a total of 633 CT images and panoramic X-ray images belonging to three groups with different conditions were used.　These images were 160 sets in the same person group and 96,820 in the other groups. The similarity of alveolar bone images was calculated using the landmark method of Procrustes analysis. The processes were system implemented and the methodology was validated.

RESULTS

The ability to identify between the same person group and other person groups showed 0.9769 as the area under the curve (AUC: ROC curve). At the cutoff value of 4.978, there was no false rejection rate, but false acceptance rate was slightly higher.

CONCLUSION

This method was useful as a screening method for personal identification. In addition, system implementation was efficient and reduced human error. In the future, we aim to realize a more efficient personal identification method using distortion-corrected images and including auto-detective landmarks using deep learning.

Definition of the Region of Interest for the Assessment of Alveolar Bone Repair Using Micro-computed Tomography

The objective of this study was to evaluate the influence of the extraction socket (distal or lingual root) and the type of region of interest (ROI) definition (manual or predefined) on the assessment of alveolar repair following tooth extraction using micro-computed tomography (micro-CT). The software package used for scanning, reconstruction, reorientation, and analysis of images (NRecon®, DataViewer®, CT-Analyzer®) was acquired through Bruker <  https://www.bruker.com  > . The sample comprised the micro-CT volumes of seven Wistar rat mandibles, in which the right first molar was extracted. The reconstructed images were analyzed using the extraction sockets, i.e., the distal and intermediate lingual root and the method of ROI definition: manual (MA), central round (CR), and peripheral round (PR). The bone volume fraction (BV/TV) values obtained were analyzed by two-way ANOVA with Tukey's post hoc test (α = 5%). The distal extraction socket resulted in significantly lower BV/TV values than the intermediate lingual socket for MA (P = 0.001), CR (P < 0.001), and PR (P < 0.001). Regarding the ROI, when evaluating the distal extraction socket, the BV/TV was significantly higher (P < 0.001) for MA than for CR and PR, with a lower BV/TV for CR. However, no significant difference was observed for MA (P = 0.855), CR (P = 0.769), or PR (P = 0.453) in the intermediate lingual extraction socket. The bone neoformation outcome (BV/TV) for alveolar bone repair after tooth extraction is significantly influenced by the ROI and the extraction socket. Using the predefined method with a standardized ROI in the central region of the distal extraction socket resulted in the assessment of bone volume, demonstrating the most critical region of the bone neoformation process.

In utero and lactational exposure to methylmercury elicits physical-chemical and morphological damages in the alveolar bone of offspring rats: The first toxicological findings

Methylmercury (MeHg) is the most common organic form of mercury (Hg) that humans are exposed and is considered an environmental pollutant. Several populations that live in endemic regions of MeHg exposure are subject to the toxicant for long periods, including pregnant women and children, causing damage to several organs during early periods of development. Alveolar bone is an essential structure for the oral cavity, responsible for supporting teeth and masticatory forces. However, evidence on the effects of MeHg on alveolar bone and the intrauterine and lactation period is lacking. Thus, this study aimed to investigate the effects of MeHg exposure during gestation and lactation on the developing alveolar bone of offspring rats after maternal exposure. Dams were exposed during 41 days of pregnancy and lactation, and the mandibles of the offspring were collected. The alveolar bone was analyzed by Fourier Transform Infrared Spectroscopy to evaluate the physicochemical composition; by Scanning Electron Microscopy for ultrastructural evaluation; by histopathological, histochemical, and morphometric for tissue analyses. In addition, bone quality was assessed by X-ray microtomography. MeHg exposure altered the mineral composition and caused histological damage associated with a lower quantity and thickness of bone trabeculae, as well as reduced osteocyte density and collagen fiber content. A reduction in trabecular thickness and bone volume and an increase in trabecular spaces were observed and were associated with anatomical compromise of the vertical bone dimensions. Thus, the results suggest that the developing alveolar bone is susceptible to the toxic effects of MeHg when organisms are exposed during intrauterine and lactation periods. From a translational perspective, these changes in the alveolar bone can help us understand possible abnormalities induced by toxic metals and highlight the need for care for structures other than those already seen as targets for damage triggered by environmental MeHg exposure.

The Outcomes of Vertical Alveolar Bone Augmentation by Guided Bone Regeneration with Titanium Mesh: A Systematic Review

AIM

This study aimed to systematically review the published studies on vertical alveolar bone augmentation (VABA) by guided bone regeneration (GBR) with titanium mesh (TM).

BACKGROUND

Guided bone regeneration is a procedure that can be used for VABA of the alveolar ridge. Titanium mesh is used as a barrier due to its ability to maintain a space that the newly formed bone will occupy.

MATERIALS AND METHODS

A computerized literature search was conducted on the databases PubMed, SCOPUS, Science Direct, and Cochrane Library to review the published article on VABA by TM from 2011 to 2021.

REVIEW RESULTS

Eight out of 574 retrieved articles were included in the qualitative analysis, three randomized clinical trials, two prospective clinical trials, and three retrospective trials. They were assessed for risk of bias using the critical appraisal skills program checklist. Titanium mesh was utilized as a barrier in three different ways, adapted directly on the alveolar bone, bent preoperatively on three-dimensional (3D) models, and 3D-printed. Two randomized clinical trials (RCTs) reported 20.8% bone gain, while the other studies reported the means ranging from 2.56 to 4.78 mm. All studies reported TM exposure that ranged from 7.69 to 66.66%. Exposure during the four postoperative weeks led to inadequate bone regeneration. However, late exposure had no effect or caused only slight bone resorption. Early TM removal was performed in two studies, one case per each, ranging from 2.4 to 11.1%. Infection was presented in three studies, one case per each, and the percentages were 5, 11.1, and 25%.

CONCLUSION

All types of TM had exposure, which was the most common complication, but early removal was indicated only in a few cases. Titanium mesh showed reliability and efficacy as a barrier for VABA by GBR.

CLINICAL SIGNIFICANCE

By this procedure, bone height can be restored, however, meticulous follow-up is recommended for the detection and management of TM exposures.

Fluoride exposure duringintrauterine and lactation periods promotes changes in the offspring rats' alveolar bone

The importance of fluoride (F) for oral health is well established in the literature. However, evidence suggests that excessive exposure to this mineral is associated with adverse effects at different life stages and may affect many biological systems, especially mineralized tissues. The purpose of this study was to investigate the effects of F exposure during pregnancy and breastfeeding on the alveolar bone of the offspring since the alveolar bone is one of the supporting components of the dental elements. For this, the progeny rats were divided into three groups: control, 10 mg F/L, and 50 mg F/L for 42 (gestational and lactation periods). Analysis of the quantification of F levels in the alveolar bone by particle-induced gamma emission; Raman spectroscopy to investigate the physicochemical aspects and mineral components; computed microtomography to evaluate the alveolar bone microstructure and analyses were performed to evaluate osteocyte density and collagen quantification using polarized light microscopy. The results showed an increase in F levels in the alveolar bone, promoted changes in the chemical components in the bone of the 50 mg F/L animals (p < 0.001), and had repercussions on the microstructure of the alveolar bone, evidenced in the 10 mg F/L and 50 mg F/L groups (p < 0.001). Furthermore, F was able to modulate the content of organic bone matrix, mainly collagen; thus, this damage possibly reduced the amount of bone tissue and consequently increased the root exposure area of the exposed groups in comparison to a control group (p < 0.001). Our findings reveal that Fcan modulate the physicochemical and microstructural dimensions and reduction of alveolar bone height, increasing the exposed root region of the offspring during the prenatal and postnatal period. These findings suggest that F can modulate alveolar bone mechanical strength and force dissipation functionality.

Polymeric Nanotechnologies for the Treatment of Periodontitis: A Chronological Review

Periodontitis is a chronic infectious and inflammatory disease of periodontal tissues estimated to affect 70 - 80 % of all adults. At the same time, periodontium, the site of periodontal pathologies, is an extraordinarily complex plexus of soft and hard tissues, the regeneration of which using even the most advanced forms of tissue engineering continues to be a challenge. Nanotechnologies, meanwhile, have provided exquisite tools for producing biomaterials and pharmaceutical formulations capable of elevating the efficacies of standard pharmacotherapies and surgical approaches to whole new levels. A bibliographic analysis provided here demonstrates a continuously increasing research output of studies on the use of nanotechnologies in the management of periodontal disease, even when they are normalized to the total output of studies on periodontitis. The great majority of biomaterials used to tackle periodontitis, including those that pioneered this interesting field, have been polymeric. In this article, a chronological review of polymeric nanotechnologies for the treatment of periodontitis is provided, focusing on the major conceptual innovations since the late 1990s, when the first nanostructures for the treatment of periodontal diseases were fabricated. In the opening sections, the etiology and pathogenesis of periodontitis and the anatomical and histological characteristics of the periodontium are being described, along with the general clinical manifestations of the disease and the standard means of its therapy. The most prospective chemistries in the design of polymers for these applications are also elaborated. It is concluded that the amount of innovation in this field is on the rise, despite the fact that most studies are focused on the refinement of already established paradigms in tissue engineering rather than on the development of revolutionary new concepts.

Sclerostin is a promising therapeutic target for oral inflammation and regenerative dentistry

Sclerostin is the protein product of the SOST gene and is known for its inhibitory effects on bone formation. The monoclonal antibody against sclerostin has been approved as a novel treatment method for osteoporosis. Oral health is one of the essential aspects of general human health. Hereditary bone dysplasia syndrome caused by sclerostin deficiency is often accompanied by some dental malformations, inspiring the therapeutic exploration of sclerostin in the oral and dental fields. Recent studies have found that sclerostin is expressed in several functional cell types in oral tissues, and the expression level of sclerostin is altered in pathological conditions. Sclerostin not only exerts similar negative outcomes on the formation of alveolar bone and bone-like tissues, including dentin and cementum, but also participates in the development of oral inflammatory diseases such as periodontitis, pulpitis, and peri-implantitis. This review aims to highlight related research progress of sclerostin in oral cavity, propose necessary further research in this field, and discuss its potential as a therapeutic target for dental indications and regenerative dentistry.

Low-intensity pulsed ultrasound enhances bone marrow-derived stem cells-based periodontal regenerative therapies

BACKGROUND

Alveolar bone loss is one of the most common consequence for periodontitis, which is a major obstacle in periodontal regeneration. Bone marrow stromal cells (BMSCs) have shown significant promise in the treatment of various disease, which also contribute to the natural bone repair process. Low-intensity pulsed ultrasound (LIPUS) is a therapeutic ultrasound used in our previous studies to promotes alveolar bone regeneration. In addition, LIPUS was found to be a promising method to enhance mesenchymal stromal cell-based therapies. In the current study, we have investigated the effects of LIPUS combined with BMSCs therapies on BMSCs homing and its potential to promote alveolar bone regeneration.

METHODS

BMSCs were isolated from rat and characterized by multilineages differentiation assay. Then these cells were labeled with luciferase and green fluorescent protein (GFP) by lentivirus in vitro. Periodontal bone defect was made on the mesial area of the maxillary first molar in rats. A total of 1 × 10⁶ Luc-GFP labeled BMSCs were injected into rat tail vein. Bioluminescence imaging was utilized to track BMSCs in vivo. The rats were sacrificed eight weeks after surgery and the samples were harvested. Micro-computed tomography (Micro-CT) was performed to evaluate alveolar bone regeneration. Paraffin sections were made and subject to hematoxylin-eosin staining, masson staining and immunohistochemistry staining.

RESULTS

BMSCs display a fibroblast-like morphology and can differentiate into adipocytes or osteoblasts under appropriate condition. The transfected BMSCs are strongly positive for GFP express. Bioluminescence imaging showed that most of BMSCs were trapped in the lung. A small portion BMSCs were homed to the alveolar bone defect area in BMSCs group, while more cells were observed in BMSCs/LIPUS group compare to other groups on day 3 and 7. Micro-CT results showed that BMSCs/LIPUS group resulted in more new bone formation than other groups. Immunohistochemical results showed higher expression of COL-I and osteopontin in BMSCs/LIPUS group compared with the other groups.

CONCLUSIONS

These results suggested that LIPUS can enhance BMSCs-based periodontal alveolar bone regeneration. This study provides new insights into how LIPUS might provide therapeutic benefits by promoting BMSCs homing.

Clinical application of concentrate growth factors combined with bone substitute in Alveolar ridge preservation of anterior teeth

Objective

To investigate the clinical effect of concentrated growth factors (CGF) combined with deproteinized bovine bone mineral (DBBM) on Alveolar ridge preservation during implantology.

Methods

A total of 38 patients were selected and randomly divided into 2 groups, with 19 cases in each group. The extraction sockets were filled with DBBM with or without CGF. Visual analogue scale (VAS) pain score was recorded within1 week and Landry wound healing index (LWHI) was recorded at 1, 2 and 3 weeks after operation. CBCT was taken preoperatively and 3 and 6 months postoperatively to measure and compare the changes of vertical height, width and gray value of alveolar bone at extraction site. The changes of alveolar bone contour were observed clinically and compared between the two groups.

Results

The VAS score of CGF group was lower than control group on the 1st and 3rd day after operation (P < 0.05). The LWHI of CGF group was higher than control group 1 week after operation (P < 0.05). The absorption of the labial and palatal plates height and the width in the CGF group was significantly less than the control group at 3 months (P < 0.05). The gray value of alveolar bone in CGF group was significantly higher than control group at 3 months (P < 0.05). There was no significant difference in new bone contour between the two groups (P > 0.05). 94.7% cases in CGF group did not undergo bone grafting, which was significantly higher than control group (78.9%).

Conclusions

The use of CGF combined with DBBM can help to reduce postoperative pain at the early stage of healing, form sufficient keratinized gingival tissue, effectively maintain the height and width of alveolar bone in the three-dimensional direction and provide good conditions for implant repair in the future.

Transplantation of bone marrow mesenchymal stem cells and fibrin glue into extraction socket in maxilla promoted bone regeneration in osteoporosis rat

AIMS

Bone defect repair in osteoporosis remains a tremendous challenge for clinicians due to increased bone metabolism resulted from estrogen deficiency. This study aims to investigate the effect of bone marrow mesenchymal stem cells (BMSCs) combined with fibrin glue (FG) in the extraction socket healing process of osteoporosis rats, as well as estimate the role of estrogen receptors (ERs) played in BMSCs differentiation in vitro and in the alveolar bone reconstruction process in vivo.

MAIN METHODS

Forty rats were randomly divided into four groups, under general anesthesia, three groups underwent bilateral ovariectomy(OVX) and one group with the sham operation. Three months later, the osteogenic ability of BMSCs, isolated from healthy and osteoporosis rats, respectively, was tested. The ERα and ERβ mRNA expression in BMSCs was also evaluated by RT-PCR analysis. In vivo experiment, Micro-CT detection, histological and immunofluorescent analysis, tissue PCR was conducted up to 2, 4 and 6 weeks after transplantation of BMSCs/FG to assess the newly formed bone in the extraction socket.

KEY FINDINGS

The BMSCs from osteoporosis rats displayed weaker osteogenic potential and lower ERs expression compared with the BMSCs from healthy rats. Newly formed bone tissue filled the socket defect in BMSCs/FG treated VOX rats after six weeks, which was comparable to the sham group, while reduced ERs expression was found in the regenerated bone of the OVX group.

SIGNIFICANCE

The BMSCs seeded within FG might provide an alternative therapeutic method for repairing the extraction socket defect in osteoporosis condition.

Effects of inorganic mercury exposure in the alveolar bone of rats: an approach of qualitative and morphological aspects

BACKGROUND

In comparison to organic mercury (MeHg), the environmental inorganic mercury (IHg) can be found in some skin-lightening cosmestics were considered "harmless" for a long time. However, recent studies have shown that long-term exposure to low doses of IHg may affect biological systems. Therefore, this study investigated the effects of IHg long-term exposure to the alveolar bone of adult rats.

METHODS

Adult Wistar rats were distributed in control and HgCl₂ exposed (0.375 mg/kg/day). After 45 days, the rats were euthanized and both blood and hemimandibles were collected. Total blood Hg levels were measured and both inorganic and organic components of the alveolar bone were determined through XRD and ATR-FTIR. The microstructure of the alveolar bone was assessed by using micro-CT and the morphometric analysis was performed by using stereomicroscopy.

RESULTS

Alterations in the physicochemical components of the alveolar bone of exposed animals were observed. The bone changes represented a tissue reaction at the microstructural level, such as bone volume increase. However, no significant dimensional changes (bone height) were observed.

CONCLUSION

Exposure to IHg at this dose can promote microstructural changes and alteration in the organic and inorganic components in the alveolar bone.

Optimizing dimensional changes of soft tissue in alveolar ridge preservation using rotational palatal pedicle flap in posterior maxilla - A randomized controlled clinical trial

Background

After tooth extraction, it is critical to maintain alveolar bone proportions as well as soft tissue integrity for rehabilitation. The common procedure for closing the socket is a coronally advanced flap, however, it compromises the keratinized tissue dimensions. As a result, the current study's goal is to assess and compare the soft tissue dimensional alterations caused by the new palatal rotational pedicle flap versus the conventional coronally advanced flap as an adjunct to alveolar ridge preservation.

Materials and Methods

Fifty-four participants requiring extraction of single maxillary posterior teeth were randomized into two groups. While both groups used a 1:1 mixture of demineralized freeze dried bone allograft and platelet rich fibrin to preserve the ridge after atraumatic extraction, the control group used a coronally advanced flap to seal the socket, whereas the test group used a rotational palatal pedicle flap to close the socket. At baseline, 3 and 6 months after surgery, the clinical parameters, i.e., vertical ridge height (VRH), horizontal ridge width (HRW), width of keratinized gingiva (WKG), thickness of keratinized gingiva (TKG), and papillary height (PH) were measured.

Results

Intergroup comparison demonstrated a significantly greater gain in WKG (P = 0.001), TKG (P = 0.029) and PH (P = 0.021) in the test group. The VRH and HRW, on the other hand, were preserved in both groups. The data were analyzed using unpaired t-test for intergroup and analysis of variance for intragroup comparison.

Conclusion

Both groups effectively preserved hard tissue dimensional changes, with the test group showing superior soft tissue enhancement.

Applications of Teriparatide for Alveolar Bone Regeneration: A Systematic Review

AIM

The aim of this study was to systematically review the applications of teriparatide (TP) for alveolar bone regeneration in oral cavity.

MATERIALS AND METHODS

An electronic search of the data was conducted in Medline (PubMed), Scopus, Web of Science, and Embase. The original research associated with the applications of TP for alveolar bone regeneration was evaluated. Cochrane's tool [for human randomized controlled trials (RCTs)] and SYRCLE's tool (for animal RCTs) were used to assess the risk of bias. About two human and four animal studies had low risk of bias.

RESULTS

The results from the 11 studies that were included in the review showed that TP enhanced alveolar bone formation in osteonecrosis of jaws, chronic periodontitis (CP), osseointegration of dental implants as well as orthodontic tooth movement.

CONCLUSION

The TP may be applied for alveolar bone regeneration in osteonecrosis of jaws and CP. However, further human clinical trials are required to verify its applications and adverse effects in various oral bone conditions.

Biomarkers and Periodontal Regenerative Approaches

The ultimate goal in periodontal therapy is the complete re-establishment of the lost tissues. Dental researchers and clinicians are continuously working to develop current therapeutic techniques and technologies that can regenerate damaged periodontal tissues. Predicting the outcome of the treatment is a challenging endeavor, because a variety of local and systemic variables can affect the success of the applied regenerative therapy. To real-time monitor the biological changes during periodontitis or after periodontal treatment, various biomarkers have been studied in periodontology. This article discusses the available evidence on the use of biomarkers in the detection of periodontal regeneration.

Inflammation and Periodontal Regeneration

Technological innovations in cellular and molecular aspects of tissue engineering --scaffolds, stem cells and 3D printed tissues --have been dramatically increased in the last decade. However, regenerative treatment still has challenges in translation to clinic. This is partly due to failure of addressing an essential element of wound healing, inflammation. It is now well-recognized that inflammation is an active process. This paradigm shift opened up a new avenue of therapeutic approaches called "host-modulation." Host-modulation therapies capable of modulating inflammatory response at multiple levels and mimicking the natural sequence of wound healing offer a new direction and promising clinical translation.

Hydroxypropylmethyl cellulose (HPMC) crosslinked keratin/hydroxyapatite (HA) scaffold fabrication, characterization and in vitro biocompatibility assessment as a bone graft for alveolar bone regeneration

Wool derived keratin has garnered significant advancements in the field of biomaterials for hard tissue regeneration. The main limitation of keratin-based biomaterials for bone tissue engineering is their fragile nature. This paper proposes the development of a novel hydroxypropyl methylcellulose (HPMC) crosslinked keratin scaffold, containing hydroxyapatite as a major inorganic component by freeze drying technique for alveolar bone regeneration. The prepared keratin/hydroxyapatite/HPMC (K/HA/HPMC) scaffold was characterized to study its chemical, physical, and mechanical properties by Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), Energy dispersive X-ray spectroscopy (EDX), X-Ray diffractometric (XRD) analysis. The SEM images of the scaffolds showed highly porous interconnected architecture with average pore size of 108.36 ± 22.56 while microcomputed tomographic analysis measured total porosity as 79.65 %±. Energy dispersive X-ray spectroscopic (EDX) analysis confirmed that inorganic component of scaffold was mainly composed of calcium and phosphorous ions having Ca/P molar ration of 1.6. The maximum compressive strength was found to be in the range of 0.841 ± 0.37 MPa. Furthermore, the K/HA/HPMC scaffold was structurally stable and weight loss of about 26% was observed when soaked in phosphate buffered solution (PBS) for 28 days. In vitro biocompatibility testing showed that K/HA/HPMC scaffold was cytocompatible and supported the attachment, proliferation of osteoblast (Saos-2) cells. Thus, the development of a non-toxic chemical cross-linking system with HPMC was investigated to fabricate K/HA/HPMC scaffold and our results showed great potential of these scaffolds to regenerate alveolar bone due to their structural similarity and excellent in vitro biocompatibility.