Early healing of the alveolar process after tooth extraction: an experimental study in the beagle dog

Influence of freeze-dried bone allograft on free gingival graft survival and alveolar ridge maintenance in socket seal procedures: a randomized controlled clinical trial

PURPOSE

This study aimed to investigate the viability of free gingival grafts (FGG) and assess clinical and radiographic changes in the alveolar ridge following socket seal surgery with or without freeze-dried bone allograft (FDBA).

MATERIALS AND METHODS

Twenty-eight anterior and premolar tooth extractions were randomly allocated to 2 groups: socket graft of FDBA sealed with FGG (n = 15) and control with empty sockets sealed solely with FGG (n = 13). Photographs taken at 3, 7, 14, and 30 days post-surgery assessed FGG viability. Alveolar ridge volume was clinically evaluated via intraoral scanners before surgery and at 1 and 3 months post-surgery. CBCT scans taken immediately post-surgery and 3 months later assessed alveolar ridge dimensions.

RESULTS

FGG viability in both groups increased from day 3 and reached the maximum score on day 14. Alveolar ridge volume reduction at 3 months in the FDBA group was comparable to the control group. Buccal alveolar bone height reduction was significantly higher in the FDBA group than the control group, while palatal alveolar bone height was comparable. Alveolar bone width reduction was evident but not statistically significant between the groups. The FDBA group exhibited a significant alteration in bone volume compared to the control group.

CONCLUSION

Viability of FGG was not affected by graft filling materials. Sealing the socket with FGG effectively preserved socket integrity and ridge volume in minor socket defects using either graft filling material or not. This study was registered on 4 January 2021 on Thai Clinical Trials Registry (TCTR20210104001).

Histologic wound healing in studies using different ridge preservation protocols: A review

BACKGROUND

Alveolar ridge preservation (ARP) procedures are designed to lessen dimensional changes in the alveolar ridge after tooth extraction. Wound healing after ridge preservation involves the formation of new vital bone in the former socket, and this vital bone is important in the osseointegration of dental implants.

METHODS

A series of ARP studies have been performed to help clinicians better understand the wound-healing events that occur following tooth extraction and ridge preservation. Different protocols have been examined using various materials and periods of healing time prior to implant placement. The primary aim of these studies was to ascertain the relative percentage of vital bone formation, residual graft material, and connective tissue (CT)/other at the healing site using histomorphometric examination of bone core biopsies obtained during osteotomy preparation.

RESULTS

For allografts, the use of demineralized bone alone or in combination with mineralized is associated with more vital bone formation than the use of mineralized allograft alone. For mineralized allografts, the use of cortical versus cancellous bone has only minimal impact on new bone formation. Xenografts from bovine and porcine sources appear to have similar vital bone formation. Longer healing times prior to implant placement are associated with increased vital bone formation and decreased residual graft material. The most stable component in most studies is the percentage of CT/other.

CONCLUSIONS

The percentage of vital bone and residual graft at ARP sites is dependent on the materials used and the length of healing time prior to obtaining core biopsies.

KEY POINTS

What factors may affect the amount of new bone at the ARP site? At a time point about 4 months after ARP, the type of graft material used for ARP plays a large role in new bone formation. Studies focus on means and standard deviations, but patients often do not "follow the mean." Even if a single ARP protocol is used for all patients, there is great interindividual variability in new bone formation, and there is often variability between sites within a single patient. How long after ARP with an allograft should I wait to place an implant? Longer healing times such as 4-5 months generally provide higher amounts of vital bone formation than shorter healing times like 2-3 months. Differences in vital bone formation between ARP protocols tend to decrease with longer healing time. FDBA that contains demineralized bone, either alone or combined with mineralized FDBA, often provides higher amounts of new bone formation than 100% mineralized allograft, especially at shorter healing periods. Even a year after ARP with an allograft, residual graft material is often still present at the ARP site.

Autologous Tooth Granulometry and Specific Surface Area with Three Grinding Methods: An In Vitro Study

A postextraction socket becomes a clinical challenge due to the fact that a series of changes associated with bone remodelling and resorption of the socket that occur after extraction, which limits the aesthetic and functional prognosis of implant-supported rehabilitations. It has been studied that the use of the autologous tooth-derived graft (ATDG) has regenerative properties and could therefore be useful for solving this type of problem. There is no consensus in the scientific literature on a standardized protocol for the use of the autologous tooth. Therefore, the aim of the present study was to evaluate the most relevant parameters to achieve the best properties of ground ATDG using three methods, namely Gouge forceps, electric grinder, and manual, that made up the study group (SG) and compared with the control group (CG) consisting of Bio-Oss®. The sample obtained by the electric grinder had the highest value of specific surface area (2.4025 ± 0.0218 m2/g), while the particle size as average diameter (751.9 µm) was the lowest and most homogeneous of the three groups. Therefore, the electric grinder allowed for obtaining ATDG with more regenerative properties due to its specific surface-area value and particle size in accordance with the xenograft with the greatest bibliographical support (Bio-Oss®). The higher specific surface increases the reaction with the physiological media, producing faster biological mechanisms.

Efficacy of alveolar ridge preservation with xenografts and resorbable socket sealing materials in the esthetic region: A systematic review with meta-analyses

AIM

The present systematic review aimed to identify and summarize the clinical, radiographic, and histological outcomes of alveolar ridge preservation using bone xenografts and absorbable sealing materials compared with spontaneous healing in the esthetic zone.

MATERIALS AND METHODS

Randomized clinical trials (RCTs) fulfilling specific eligibility criteria were included. Two review authors independently searched for eligible studies, extracted data from the published reports and performed the risk of bias assessment (RoB 2 tool). Study results were summarized using random effects meta-analyses.

RESULTS

Thirteen articles concerning 10 RCTs were included, involving a total of 357 participants. Most of studies were considered as "low" risk of bias. Meta-analyses indicated less horizontal (difference in means-MD = 1.88 mm; p < 0.001), vertical mid-buccal (MD = 1.84 mm; p < 0.001) and vertical mid-lingual (MD = 2.27 mm; p < 0.001) bone resorption in alveolar ridge preservation compared to spontaneous healing as assessed clinically. Bone changes assessed radiographically showed consistent results in terms of horizontal (at 1 mm: MD = 1.84 mm, p < 0.001), vertical mid-buccal (MD = 0.95 mm; p < 0.001) and mid-lingual (MD = 0.62 mm; p = 0.05) resorption. Part of the bone resorption in the spontaneous healing group was compensated by soft-tissues, since the observed differences between groups in linear ridge reduction evaluated through cast models superimposition were smaller (MD = 0.52 mm; p < 0.001).

CONCLUSIONS

Alveolar ridge preservation with xenogeneic bone substitutes and non-autogenous resorbable socket sealing materials is efficacious in reducing post-extraction bone and ridge changes in the esthetic region.

Efficacy of autogenous particulated dentin graft for alveolar ridge preservation: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Autogenous particulate dentin (APD) has been used as a bone graft material for bone augmentation, but the specifics of its effect on alveolar ridge preservation (ARP) are uncertain. The aim of this study was to investigate the clinical and histomorphometric performance of APD compared with blood clot healing or other grafted materials in ARP.

METHODS

MEDLINE, Embase, Web of Science, Scopus and the Cochrane Library and citation databases were searched until August 2, 2023 to identify randomized controlled trials that employed APD for ARP. Two independent meta-analyses were performed based on the different control groups (Group I: blood clot healing; Group II: other grafted materials). Weighted or mean differences (MDs) and corresponding 95% confidence intervals (CIs) were calculated. The protocol was prospectively registered with PROSPERO (CRD42023409339).

RESULTS

A total of 238 records were identified, of which ten studies with 182 participants were included. The meta-analysis indicated that APD resulted in fewer changes in horizontal ridge width (Group I: MD = 1.61, 95% CI 0.76-2.46; Group II: MD = 1.28, 95% CI 1.08-1.48) and labial bone height (Group I: MD = 1.75, 95% CI 0.56-2.94; Group II: P < .05) than the control treatments. Regarding histomorphometry, APD yielded a satisfactory proportion of vital bone area (MD = 10.51, 95% CI 4.70-16.32) and residual material area (MD = -8.76, 95% CI -12.81 to -4.71) in Group II, while there was no significant difference in Group I. Moreover, none of the secondary outcomes were significantly differed between groups.

CONCLUSION

Within this study limitations, APD effectively maintained the horizontal and vertical dimensions of the extraction sockets and exhibited favorable osteogenic properties and degradation capacity. Further well-designed randomized controlled trials with larger samples and longer follow-up periods are needed to evaluate whether APD is superior to other substitutes for ARP.

Application of virtual technology to maximize esthetics and function in the restoration of anterior traumatic dental injuries

The restoration of multiple teeth with traumatic injury in the esthetic zone is complex. For the present patient, an intraoral scanner, a facial scanner, a jaw motion analyzer, and cone beam computed tomography were applied to collect patient data and establish a virtual dental patient. The virtual technology increased the accuracy of tooth- and implant-supported crowns in both appearance and occlusion.

Conjugation of bone grafts with NO-delivery dinitrosyl iron complexes promotes synergistic osteogenesis and angiogenesis in rat calvaria bone defects

Craniofacial/jawbone deformities remain a significant clinical challenge in restoring facial/dental functions and esthetics. Despite the reported therapeutics for clinical bone tissue regeneration, the bioavailability issue of autografts and limited regeneration efficacy of xenografts/synthetic bone substitutes, however, inspire continued efforts towards functional conjugation and improvement of bioactive bone graft materials. Regarding the potential of nitric oxide (NO) in tissue engineering, herein, functional conjugation of NO-delivery dinitrosyl iron complex (DNIC) and osteoconductive bone graft materials was performed to optimize the spatiotemporal control over the delivery of NO and to activate synergistic osteogenesis and angiogenesis in rat calvaria bone defects. Among three types of biomimetic DNICs, [Fe2(μ-SCH2CH2COOH)2(NO)4] (DNIC-COOH) features a steady kinetics for cellular uptake by MC3T3-E1 osteoblast cells followed by intracellular assembly of protein-bound DNICs and release of NO. This steady kinetics for intracellular delivery of NO by DNIC-COOH rationalizes its biocompatibility and wide-spectrum cell proliferation effects on MC3T3-E1 osteoblast cells and human umbilical vein endothelial cells (HUVECs). Moreover, the bridging [SCH2CH2COOH]- thiolate ligands in DNIC-COOH facilitate its chemisorption to deproteinized bovine bone mineral (DBBM) and physisorption onto TCP (β-tricalcium phosphate), respectively, which provides a mechanism to control the kinetics for the local release of loaded DNIC-COOH. Using rats with calvaria bone defects as an in vivo model, DNIC-DBBM/DNIC-TCP promotes the osteogenic and angiogenic activity ascribed to functional conjugation of osteoconductive bone graft materials and NO-delivery DNIC-COOH. Of importance, the therapeutic efficacy of DNIC-DBBM/DNIC-TCP on enhanced compact bone formation after treatment for 4 and 12 weeks supports the potential for clinical application to regenerative medicine.

Dental Restorations

Fulfilling a patient's request for a healthy, functional and esthetic smile represents a daily challenge for dental practitioners [...].

Efficacy of the application of leukocyte and platelet-rich fibrin (L-PRF) on alveolar ridge preservation. A randomized controlled clinical trial

INTRODUCTION

Alveolar ridge preservation (ARP) is a well-defined treatment performed to reduce bone dimensional changes occurring during the healing of post-extraction sockets to allow for adequate implant placement. Leukocyte and platelet-rich fibrin (L-PRF) has been showing to potentially promote bone and tissue regeneration during wound healing. Therefore, the aim of this study is to evaluate its efficacy for ARP when applied to fresh extraction sockets, in comparison with spontaneous healing.

MATERIALS AND METHODS

Twenty-seven patients with hopeless non-molar teeth were treated. After randomization, fresh extraction sockets were either filled with L-PRF or allowed to heal spontaneously. CBCTs and intraoral scans were obtained immediately after extraction and at 4 months. Through superimposition of the obtained images, changes in the horizontal ridge width, height, buccal volume, and ridge contour changes were measured, as well as patient-reported outcome measures (PROM's).

RESULTS

The ridge dimensions changed similarly in both groups. Although less reduction occurred in the test group at 1 mm from the bone crest, differences were not statistically significant (p > 0.05). Application of L-PRF did not prevent reductions of ridge contours, neither in the linear vertical aspect nor in volumetric changes. There were no differences between groups in the need for bone regeneration when placing implants. Patients in both groups reported similar outcomes in terms of bleeding, pain, inflammation, and function at 1 and 4 weeks postoperatively.

CONCLUSION

Alveolar preservation with L-PRF neither minimized bone resorption occurring after tooth extraction in non-molar sites nor reduced the need for bone regeneration when placing implants. Furthermore, its use did not improve PROM's.

Therapeutic Efficacy of Bromelain in Alveolar Ridge Preservation

Most of research in regenerative oral surgery describes materials or techniques for increasing volumetric results for implant-supported prosthesis. The use of bio-materials in alveolar ridge preservation after tooth extraction commonly leads to a delayed recovery. Bromelain is an enzyme that belongs to a family of proteolytic enzymes derived from the stem of the pineapple plant (Ananas comosus) with effectiveness in decreasing the inflammation development and swelling. The present paper reports a prospective comparative study performed in order to test the possible use of oral bromelain 40 mg in alveolar ridge preservation. Evaluations were performed at three time points after the surgery: after 2 days (t1), after 7 days (t2) and after 14 days (t3). A statistically significant difference among patients that used bromelain and patients that used placebo resulted among the use of bromelain and lower Visual Analogue Scale (VAS) at t1 (r = -0.75, p = 0.0067), t2 (r = -0.90, p = 0.0001) and t3 (r = -0.8566, p = 0.0008). Bromelain therapy reported a statistically significant difference among patients that used bromelain and patients that used placebo even with regards to the use of bromelain and postoperative swelling at t1 (r = -0.79, p = 0.0034), t2 (r = -0.81, p = 0.0020) but not at t3 (r = -0.34, p = 0.2967). With the result of the present paper, and the poorness of contraindication of the investigated drug, bromelain may be suggested to be used for patients that undergo to alveolar ridge preservation after tooth extraction.

Comparison of 0.12% Chlorhexidine and a New Bone Bioactive Liquid, BBL, in Mouthwash for Oral Wound Healing: A Randomized, Double Blind Clinical Human Trial

Following surgery, healing within the oral cavity occurs in a hostile environment, and proper oral care and hygiene are required to accelerate recovery. The aim of the current study is to investigate and compare the bioreactivity characteristics of mouthwashes based on either chlorhexidine (CHX) or a novel bone bioactive liquid (BBL) in terms of oral healing within seven days application post-surgery. A randomized, double blind clinical trial was conducted in 81 patients, wherein the mouthwashes were applied twice a day for a period of 7 days. The visual analog scale (VAS) protocol was applied to determine pain index scores. Early wound healing index (EHI) score was determined for evaluating oral cavity healing progress. No adverse effects were observed using the mouthwashes, but CHX application resulted in stained teeth. Applications of both CHX and BBL were sufficient to reduce pain over a period of 7 days. However, the BBL group demonstrated a statistically significant reduction in VAS scores starting on day 4. The EHI scores were significantly higher in the BBL group compared with the CHX group, independent of tooth location. No differences in either VAS or EHI scores due to gender were observed. Compared with the commercially available CHX mouthwash, application of the BBL mouthwash reduced pain and accelerated oral cavity healing to a greater extent, suggesting it effectively improves the oral cavity microenvironment at the wound site in mediating soft tissue regeneration.

Alveolar Bone Remodeling with or without Collagen Filling of the Extraction Socket: A High-Resolution X-ray Tomography Animal Study

The healing process of the tooth extraction socket often leads to significant resorption of the alveolar bone, eventually causing clinical difficulties for future implant-supported rehabilitations. The aim of the present animal study was to evaluate alveolar bone remodeling after tooth extraction in a rabbit model, either with or without the use of a plain collagen plug inside the socket, by means of micro-computed tomography. The study included the micro-tomography analysis of 36 rabbits’ incisor extraction sockets, either left empty or filled with a collagen plug. All animals were euthanized in a staggered manner, in order to address molecular, histologic, and radiographic analyses at different time-points, up to 90 days after surgery. The three-dimensional evaluation was carried out using micro-computed tomography technology on excised bone blocks including the alveolus and the contralateral bone. Both linear and volumetric measures were recorded: the percentage of bone volume change (ΔBV) within the region of interest was considered the primary endpoint of the study. The micro-CT analysis revealed mean volumetric changes of −58.1% ± from baseline to 3 months for the control group, and almost no bone loss for the test group, −4.6%. The sockets treated with the collagen plug showed significantly less dimensional resorption, while the natural-healing group showed an evident collapse of the alveolar bone three months after extraction surgery.

A comparative study of the effects of platelet-rich fibrin, concentrated growth factor and platelet-poor plasma on the healing of tooth extraction sockets in rabbits

BACKGROUND

Autologous platelet concentrate has been widely used to encourage the regeneration of hard and soft tissues. Up to now, there are three generations of autologous platelet concentrates. Many studies have shown that the three autologous concentrates have different effects, but the specific diversities have not been studied. The purpose of this study was to explore and compare the effects of platelet-rich fibrin, concentrated growth factor and platelet-poor plasma on the healing of tooth extraction sockets in New Zealand rabbits.

METHODS

A total of 24 healthy male New Zealand white rabbits aged 8-12 weeks were selected. The experimental animals were randomly divided into four groups: three experimental groups were respectively implanted with PPP, CGF and PRF gel after bilateral mandibular anterior teeth were extracted, and the control group did not implant any material. The alveolar bone of the mandibular anterior region was taken at 2, 4 and 8 weeks after operation. The height and width of the extraction wound were detected by CBCT, the growth of the new bone was observed by HE and Masson staining, and the expression of osteogenic genes was detected by real-time PCR. Data were analyzed using IBM SPSS statistical package 22.0.

RESULTS

The radiological results showed that alveolar bone resorption in all groups gradually increased over time. However, the experimental groups showed lower amounts of bone resorption. The histological results showed that new bone formation was observed in all groups. Over time, the new bone trabeculae of the CGF group became closely aligned while those in the PPP and PRF groups remained scattered. PCR results showed that the expression of BMP-2 and ALP was higher in the experimental groups than the control group.

CONCLUSION

In conclusion, the application of PRF, CGF and PPP in tooth extraction sockets effectively promoted bone regeneration. CGF showed more effective bone induction and tissue regeneration ability in the long term.

Alveolar ridge preservation reduces the need for ancillary bone augmentation in the context of implant therapy

Background

There is limited information on the need for bone augmentation in the context of delayed implant placement whether alveolar ridge preservation (ARP) is previously performed or not. The primary aim of this retrospective cohort study was to evaluate the efficacy of ARP therapy after tooth extraction compared with unassisted socket healing (USH) in reducing the need for ancillary bone augmentation before or at the time of implant placement.

Methods

Adult subjects that underwent non‐molar single tooth extraction with or without simultaneous ARP therapy were included in this study. Cone beam computed tomography scans obtained before tooth extraction and after a variable healing period were used to record the baseline facial bone thickness and to virtually plan implant placement according to a standard method. A logistic regression model was used to evaluate the effect of facial alveolar bone thickness upon tooth extraction and baseline therapy (USH or ARP) on the need for additional bone augmentation, adjusting for several covariates (i.e., age, sex, baseline KMW, and tooth type).

Results

One hundred and forty subjects that were equally distributed between both baseline therapy groups constituted the study population. Implant placement was deemed virtually feasible in all study sites. Simultaneous bone augmentation was considered necessary in 60% and 11.4% of the sites in the USH and ARP group, respectively. Most of these sites (64.2% in the USH group and 87.5% in the ARP group) exhibited a thin facial bone phenotype (<1 mm) at baseline. Logistic regression revealed that the odds of not needing ancillary bone augmentation were 17.8 times higher in sites that received ARP therapy. Furthermore, the need for additional bone augmentation was reduced 7.7 times for every 1 mm increase in facial bone thickness, regardless of baseline therapy.

Conclusions

Based on a digital analysis, ARP therapy, compared with USH, and thick facial alveolar bone largely reduce the need for ancillary bone augmentation at the time of implant placement in non‐molar sites.

The beyond the gap filling approach: Modeling facial and interproximal tissues and improving esthetics for anterior flapless immediate implant placement

OBJECTIVE

Maintenance of adequate interproximal tissue height between an implant and a natural tooth or between adjacent implants represents an esthetic challenge in implant dentistry. The aim of this case report is to describe a modified technique referred to as the beyond the gap filling (BGF) approach designed to improve the horizontal and vertical components of the facial aspect and particularly the height of interproximal bone peaks around immediately placed implants into fresh extraction sockets.

CLINICAL CONSIDERATIONS

Four patients (five teeth) requiring anterior tooth extraction were treated with the BGF approach that included: (a) minimally traumatic tooth extraction; (b) immediate implant placement without flap elevation; (c) installation of a narrow profile healing abutment to protect the implant during grafting; (d) grafting with a construct with 90% bovine bone granules and 10% porcine collagen packed coronally to the facial and interproximal bone walls above the level of the bone crest; and (e) delivery of an immediate restoration.

CONCLUSIONS

The current report suggests that the level/height of the interproximal bone crests between an implant and a natural tooth or between two adjacent implants can be improved by the BGF approach and, consequently, papilla height can be maintained in cases with a high risk of papilla height collapse and, consequently, esthetic outcomes can be maximized.

CLINICAL SIGNIFICANCE

The BGF is a simple technique to be used by clinicians to prevent significant papilla collapse in anterior immediate implants and consequently achieve maximum esthetic outcomes in implant dentistry.

Effect of an "Autogenous Leukocyte Platelet-Rich Fibrin Tooth Graft" Combination around Immediately Placed Implants in Periodontally Compromised Sites: A Randomized Clinical Trial

Objective

Autogenous tooth bone graft (ATBG) was suggested as a source for bone grafting materials, especially as they have similar chemical composition to bone. This study goal was to assess the clinical and radiographic consequences of ATBG with or without L-PRF on bone deposition around immediate implants placed in periodontally hopeless sites.

Materials and Methods

26 patients, with periodontally diseased teeth, underwent random assignment to receive the surgical protocol either with L-PRF over ATBG around immediately inserted implants (test group) or without it (control group). Clinical examination was observed. Radiographically, bone changes horizontally and vertically to determine marginal bone loss (MBL) and mesiodistal bone changes were made at the base line and 6 and 9 months after implant insertion. Statistical analysis utilizing paired Student's t-test was used for comparing results within the same group, whereas an independent-sample t-test was used for intergroup variable comparison.

Results

All implants met the criteria of success without any complications at the follow-up period. Nonsignificant differences were detected between horizontal bone alterations in both groups at 6 and 9 months (P > .001). The test group showed statistically significant lower MBL than the control group (P < .001). The mesiodistal bone gain in the test group was significantly higher than that of the control group at the 6-month period (P < .001). The mesiodistal bone loss in the control group was significantly higher than that of the test group at the 9-month period (P < .001).

Conclusion

The ATBG- L-PRF combination therapy enhances new bone formation and appeared to be a favorable procedure with immediate implant placement, particularly in severe periodontitis cases.

A Retrospective Evaluation of Secondary Wound Healing for Extraction of the Maxillary First Molar in Dogs

Oral surgery and exodontia can present challenges in veterinary patients, with a particular area of challenge being extraction and closure of the maxillary first molar (M1) in dogs. This retrospective assessment evaluated patients that had the maxillary first molar extracted with placement of a cruciate suture across the alveolus to achieve partial closure and secure the blood clot. Patients that had teeth extracted adjacent to M1 (maxillary fourth premolar [PM4] or second molar [M2]) were excluded from the study. Three groups of patients were assessed: Group A - at the time of extraction of M1, both the maxillary PM4 and M2 were still present in the oral cavity. Group B - at the time of M1extraction only PM4 or M2 was present, but not both. The tissue was completely intact at the location of the missing tooth. Group C - at the time of M1 extraction neither PM4 or M2 were present, but tissue in these locations was intact. In a three-and-a half-year time period (2015-2018), 179 dogs with 213 solitary M1 extractions were performed. Of these 213 extraction sites, 127 sites (60%) had follow up examination within a two-week postoperative period. Of these 127 sites, 126 (99.2%) appeared appropriately healed without complication. The results of this retrospective evaluation demonstrate that primary closure of a maxillary first molar extraction site may not be required for appropriate soft tissue wound healing in canine patients.

Bone Dimensional Change Following Immediate Implant Placement in Posterior Teeth with CBCT: A 6-Month Prospective Clinical Study

This prospective clinical study aimed to evaluate the peri-implant hard tissue dimensional change at 6 months of immediate implant placement with bone graft materials in the posterior area using cone-beam computed tomography (CBCT). Twelve dental implants were placed concurrently following tooth extraction in the posterior area and filled with xenograft particles. The CBCT images were taken immediately after surgical procedures and then at 6 months follow-up. To evaluate the hard tissue changes, the vertical and horizontal bone thickness were analyzed and measured using ImageJ software. Paired t-test or Wilcoxon match-pair signed-rank test was done to analyze the changes of hard tissue values at the same level between immediately and 6 months following immediate implant placement. Independent t-test or Mann-Whitney U test was used to analyze the dimensional change in the vertical and horizontal direction in buccal and lingual aspects. The level of significance was set at p value = 0.05. All implants were successfully osseointegrated. At 6 months follow-up, the vertical bone change at the buccal aspect was -0.69 mm and at the lingual aspect -0.39 mm. For horizontal bone thickness, the bone dimensional changes at 0, 1, 5, and 9 mm levels from the implant platform were -0.62 mm, -0.70 mm, -0.24 mm, and -0.22 mm, respectively. A significant bone reduction was observed in all measurement levels during the 6 months after implant placement (p value < 0.05). It was noted that even with bone grafting, a decrease in bone thickness was seen following the immediate implant placement. Therefore, this technique can be an alternative method to place the implant in the posterior area.

Effectiveness of a Nanohydroxyapatite-Based Hydrogel on Alveolar Bone Regeneration in Post-Extraction Sockets of Dogs with Naturally Occurring Periodontitis

Pathological mandibular fracture after dental extraction usually occurs in dogs with moderate to severe periodontitis. A nanohydroxyapatite-based hydrogel (HAP hydrogel) was developed to diminish the limitations of hydroxyapatite for post-extraction socket preservation (PSP). However, the effect of the HAP hydrogel in dogs has still not been widely investigated. Moreover, there are few studies on PSP in dogs suffering from clinical periodontitis. The purpose of this study was to evaluate the effectiveness of the HAP hydrogel for PSP in dogs with periodontitis. In five dogs with periodontitis, the first molar (309 and 409) of each hemimandible was extracted. Consequently, all the ten sockets were filled with HAP-hydrogel. Intraoral radiography was performed on the day of operation and 2, 4, 8 and 12 weeks post operation. The Kruskal-Wallis test and paired t-test were adopted for alveolar bone regeneration analysis. The results demonstrated that the radiographic grading, bone height measurement, and bone regeneration analysis were positively significant at all follow-up times compared to the day of operation. Moreover, the scanning electron microscopy with energy-dispersive X-ray spectroscopy imaging after immersion showed a homogeneous distribution of apatite formation on the hydrogel surface. Our investigation suggested that the HAP hydrogel effectively enhances socket regeneration in dogs with periodontitis and can be applied as a bone substitute for PSP in veterinary dentistry.

Histologic and Histomorphometric Evaluation of a New Bioactive Liquid BBL on Implant Surface: A Preclinical Study in Foxhound Dogs

BACKGROUND

Bioactive chemical surface modifications improve the wettability and osseointegration properties of titanium implants in both animals and humans. The objective of this animal study was to investigate and compare the bioreactivity characteristics of titanium implants (BLT) pre-treated with a novel bone bioactive liquid (BBL) and the commercially available BLT-SLA active.

METHODS

Forty BLT-SLA titanium implants were placed in in four foxhound dogs. Animals were divided into two groups (n = 20): test (BLT-SLA pre-treated with BBL) and control (BLT-SLA active) implants. The implants were inserted in the post extraction sockets. After 8 and 12 weeks, the animals were sacrificed, and mandibles were extracted, containing the implants and the surrounding soft and hard tissues. Bone-to-implant contact (BIC), inter-thread bone area percentage (ITBA), soft tissue, and crestal bone loss were evaluated by histology and histomorphometry.

RESULTS

All animals were healthy with no implant loss or inflammation symptoms. All implants were clinically and histologically osseo-integrated. Relative to control groups, test implants demonstrated a significant 1.5- and 1.7-fold increase in BIC and ITBA values, respectively, at both assessment intervals. Crestal bone loss was also significantly reduced in the test group, as compared with controls, at week 8 in both the buccal crests (0.47 ± 0.32 vs 0.98 ± 0.51 mm, p < 0.05) and lingual crests (0.39* ± 0.3 vs. 0.89 ± 0.41 mm, p < 0.05). At week 12, a pronounced crestal bone loss improvement was observed in the test group (buccal, 0.41 ± 0.29 mm and lingual, 0.54 ± 0.23 mm). Tissue thickness showed comparable values at both the buccal and lingual regions and was significantly improved in the studied groups (0.82-0.92 mm vs. 33-48 mm in the control group).

CONCLUSIONS

Relative to the commercially available BLT-SLA active implants, BLT-SLA pre-treated with BBL showed improved histological and histomorphometric characteristics indicating a reduced titanium surface roughness and improved wettability, promoting healing and soft and hard tissue regeneration at the implant site.

Does Timing of Secondary Alveolar Bone Grafting Affect the Need for Additional Bone Augmentation Prior to Implant Placement at Cleft Sites?

PURPOSE

The purpose of this study was to identify factors that influence the need for a supplemental bone graft prior to dental implant placement at previously grafted alveolar cleft sites.

PATIENTS AND METHODS

Retrospective case series of patients with cleft lip/palate who had both alveolar bone grafting (ABG) and placement of a dental implant(s) to replace a missing incisor(s) at the cleft site by the senior surgeon (BLP) at Boston Children's Hospital from 2005 through 2020. Primary outcome variable was need for a supplemental bone graft prior to dental implant placement. Predictor variables included gender, cleft type (unilateral vs. bilateral), implant site, number of implants placed, age at ABG and implant placement, time between ABG and implant, history of maxillary expansion and whether the patient had a Le Fort I osteotomy to correct maxillary hypoplasia before implant placement. Descriptive statistics were computed and comparative analyses were performed using Pearson X², Fisher exact, and Mann-Whitney U tests.

RESULTS

There were 84 implants placed in 59 patients (64.2% female) with cleft lip and palate who had alveolar bone grafting of which 57.1% (n = 48) required a supplemental graft prior to placement. Median time (IQR) from alveolar bone grafting to implant placement was significantly longer in patients who required additional grafting (8.1 versus 5.4 years, P < .001). Patients who required supplemental bone were significantly younger at the time of alveolar bone grafting (10.1 versus 12.3 years, P < .001). Cleft sites in patients who had a Le Fort I osteotomy prior to implant placement required bony augmentation more often than cleft sites in patients who did not have a Le Fort I osteotomy (58.7% versus 33.3%, P = .03).

CONCLUSIONS

Patients with cleft lip and/or palate who undergo alveolar bone grafting should be counseled that they are likely to require a supplemental bone graft prior to implant placement.

Hard tissue dimensional changes following implant removal due to peri-implantitis: A retrospective study

BACKGROUND

The current evidence regarding the alterations experienced by the alveolar ridge (hard tissue changes) after implant removal due to peri-implantitis is limited.

PURPOSE

To assess the hard tissue dimensional changes following implant removal due to peri-implantitis.

MATERIAL AND METHODS

Clinical records were examined to identify patients with implants that had to be removed due to a hopeless prognosis secondary to peri-implantitis due to expendability of peri-implantitis implants for functional reasons. Patients with preoperative and postoperative cone-beam computed tomography (CBCT) scans were included. Patient-related, implant-related, and surgery-related factors were assessed based on the clinical records. Linear measurements were made to evaluate the influence of bone plate thickness (BPT), ridge width (RW), and ridge height (RH) at various levels upon the outcome of implant removal. A descriptive statistical analysis of the quantitative and qualitative variables was performed. Correlations of the variables with the primary outcome (dimensional changes) were tested using univariate and multivariate analyses (multinomial random intercept mixed model linear regressions).

RESULTS

A total of 26 patients (n_implants = 79) met the eligibility criteria. The mean decrease in RW at 1 and 3 mm below the crest was 11.3% and 4.4%, respectively (P < 0.001). Buccal and lingual RH was significantly reduced by 2.2% and 6.3%, respectively (P < 0.001). Few patient-related, implant-related, and surgery-related factors appeared to have an impact upon the hard tissue dimensional changes. Bone regeneration simultaneous to implant removal minimized the dimensional changes of the ridge both vertically (5% lesser buccal RH reduction) and horizontally (12% lesser RW reduction) when compared with spontaneous healing. The use of a reverse-torque removal kit seemed to be critical in limiting the dimensional changes of the ridge.

CONCLUSIONS

Minimal hard tissue changes can be expected following implant removal due to peri-implantitis. Simultaneous bone regeneration procedures and the use of a removal kit may considerably reduce the impact upon the dimensional changes (NCT04534361).

Silica-Based Bioactive Glasses and Their Applications in Hard Tissue Regeneration: A Review

Regenerative medicine is a field that aims to influence and improvise the processes of tissue repair and restoration and to assist the body to heal and recover. In the field of hard tissue regeneration, bio-inert materials are being predominantly used, and there is a necessity to use bioactive materials that can help in better tissue-implant interactions and facilitate the healing and regeneration process. One such bioactive material that is being focused upon and studied extensively in the past few decades is bioactive glass (BG). The original bioactive glass (45S5) is composed of silicon dioxide, sodium dioxide, calcium oxide, and phosphorus pentoxide and is mainly referred to by its commercial name Bioglass. BG is mainly used for bone tissue regeneration due to its osteoconductivity and osteostimulation properties. The bioactivity of BG, however, is highly dependent on the compositional ratio of certain glass-forming system content. The manipulation of content ratio and the element compositional flexibility of BG-forming network developed other types of bioactive glasses with controllable chemical durability and chemical affinity with bone and bioactivity. This review article mainly discusses the basic information about silica-based bioactive glasses, including their composition, processing, and properties, as well as their medical applications such as in bone regeneration, as bone grafts, and as dental implant coatings.

Leukocyte and Platelet-Rich Fibrin Have Same Effect as Blood Clot in the 3-Dimensional Alveolar Ridge Preservation. A Split-Mouth Randomized Clinical Trial

PURPOSE

Leukocyte- and platelet-rich fibrin (L-PRF) has been used for alveolar ridge preservation (ARP) in postextraction tooth sockets. However, current reports have measured its effectiveness in linear measurements of 3-dimensional ridge preservation. The purpose of this study was to determine the effectiveness of the use of L-PRF filling versus natural clot blood healing in ARP according to the clinical, radiographic, and volumetric measurements of postextraction tooth sockets.

MATERIALS AND METHODS

A split-mouth randomized clinical trial was designed. Healthy patients who needed bilateral extraction of upper third molars were selected. After the tooth extraction, the socket was filled and distributed randomly with L-PRF and the contralateral socket only with the blood clot. The dimensional change of soft tissue healing around the sockets, and the length, depth, and difference of bone formation were examined using standardized periapical radiographs. Volumetric measurement variation of the sockets was evaluated by 3-dimensional scanning of dental casts. Changes of all measures were analyzed at 7 days (initial) and 3 months (final) after the tooth extraction and compared between both groups (t test; P < .05).

RESULTS

Sixteen patients (aged 24.75 ± 3.53 years; 56.25% women) participated. Measurements of wound healing and the length, depth, and difference of bone formation were similar for both study groups at initial and final times. The calculation of initial-final volumetric socket variation was 15.45 ± 13.12 μL using L-PRF and 14.12 ± 11.23 μL using blood clot (P = .78).

CONCLUSIONS

L-PRF filling showed the same dimensional and volumetric behavior as normal blood clot healing in the ARP of postextraction tooth sockets. Future investigations will have to analyze the use of surgical models and digital instruments in ARP techniques.

Post-extraction dimensional changes: A systematic review and meta-analysis

AIM

To analyse the evidence pertaining to post-extraction dimensional changes in the alveolar ridge after unassisted socket healing.

MATERIALS AND METHODS

The protocol of this PRISMA-compliant systematic review (SRs) was registered in PROSPERO (CRD42020178857). A literature search to identify studies that fulfilled the eligibility criteria was conducted. Data of interest were extracted. Qualitative and random-effects meta-analyses were performed if at least two studies with comparable features and variables reported the same outcome of interest.

RESULTS

Twenty-eight articles were selected, of which 20 could be utilized for the conduction of quantitative analyses by method of assessment (i.e. clinical vs radiographic measurements) and location (i.e. non-molar vs molar sites). Pooled estimates revealed that mean horizontal, vertical mid-facial and mid-lingual ridge reduction assessed clinically in non-molar sites was 2.73 mm (95% CI: 2.36-3.11), 1.71 mm (95% CI: 1.30-2.12) and 1.44 mm (95% CI: 0.78-2.10), respectively. Mean horizontal, vertical mid-facial and mid-lingual ridge reduction assessed radiographically in non-molar sites was 2.54 mm (95% CI: 1.97-3.11), 1.65 mm (95% CI: 0.42-2.88) and 0.87 mm (95% CI: 0.36-1.38), respectively. Mean horizontal, vertical mid-facial and mid-lingual ridge reduction assessed radiographically in molar sites was 3.61 mm (95% CI: 3.24-3.98), 1.46 mm (95% CI: 0.73-2.20) and 1.20 mm (95% CI: 0.56-1.83), respectively.

CONCLUSION

A variable amount of alveolar bone resorption occurs after unassisted socket healing depending on tooth type.

The prevalence of peri-implant disease following immediate implant placement and loading: a cross-sectional analysis after 2 to 10 years

Background

To evaluate the prevalence of peri-implant disease after immediate implant placement and loading.

Material and methods

This cross-sectional analysis included a total of 47 patients with 64 implants exhibiting a mean loading time of 2 to 10 years (4.23 ± 1.7 years). The surgical and prosthetic procedures were standardized in all patients. Peri-implant health and disease was assessed based on the established case definitions.

Results

The prevalence of peri-implant health, peri-implant mucositis, and peri-implantitis amounted to 38.3%, 57.5%, and 4.2% of the patients, respectively. Mucosal recession of 1 mm was present at 4 (6%) implants. No suppuration, pain, or implant failures were reported. Ordinal logistic regression revealed that reduced keratinized mucosa height was significantly associated with the diagnosis of peri-implant mucositis and peri-implantitis (OR = 0.514, P = 0.0125).

Conclusion

Immediate implant placement and loading was associated with high success rates at 2 to 10 years.

Efficacy of Alveolar Ridge Preservation: A Randomized Controlled Trial

Alveolar ridge preservation (ARP) therapy is indicated to attenuate the physiologic resorptive events that occur as a consequence of tooth extraction with the purpose of facilitating tooth replacement therapy. This randomized controlled trial was primarily aimed at testing the efficacy of ARP as compared with unassisted socket healing. A secondary objective was to evaluate the effect that local phenotypic factors play in the volumetric reduction of the alveolar bone. A total of 53 subjects completed the study. Subjects were randomized into either the control group, which involved only tooth extraction (EXT n = 27), or the experimental group, which received ARP using a combination of socket grafting with a particulate bone allograft and socket sealing with a nonabsorbable membrane (dPTFE) following tooth extraction (ARP n = 26). A set of clinical, linear, volumetric, implant-related, and patient-reported outcomes were assessed during a 14-wk healing period. All linear bone assessments (horizontal, midbuccal, and midlingual reduction) revealed that ARP is superior to EXT. Likewise, volumetric bone resorption was significantly higher in the control group (mean ± SD: EXT = −15.83% ± 4.48%, ARP = −8.36% ± 3.81%, P < 0.0001). Linear regression analyses revealed that baseline buccal bone thickness is a strong predictor of alveolar bone resorption in both groups. Interestingly, no significant differences in terms of soft tissue contour change were observed between groups. Additional bone augmentation to facilitate implant placement in a prosthetically acceptable position was deemed necessary in 48.1% of the EXT sites and only 11.5% of the ARP sites ( P < 0.004). Assessment of perceived postoperative discomfort at each follow-up visit revealed a progressive decrease over time, which was comparable between groups. Although some extent of alveolar ridge remodeling occurred in both groups, ARP therapy was superior to EXT as it was more efficacious in the maintenance of alveolar bone and reduced the estimated need for additional bone augmentation at the time of implant placement (ClinicalTrials.gov NCT01794806).

Surgical Wound Healing in the Oral Cavity: a Review

Wound healing is a fundamental survival mechanism, largely taken for granted. It consists of four intricately tuned phases: haemostasis, inflammation, proliferation and remodelling. Successful wound healing only occurs if each phase occurs in the correct sequence and timeframe. Moreover, the oral cavity serves as a unique and remarkable setting whereby wound healing takes place in a saliva-filled environment containing millions of micro-organisms. Many local and systemic factors can impair oral wound healing. This article provides an overview of the wound healing process, with a discussion of these respective local and systemic factors, along with the potential cellular and/or molecular mechanisms involved.

CPD/Clinical Relevance: On a daily basis, dentists perform procedures such as exodontia and implant placement that rely on adequate wound healing. An improved understanding of the local and systemic factors that can impair oral wound healing can help clinicians to control these factors more accurately, resulting in improved patient outcomes.

Effect of alveolar ridge preservation interventions following tooth extraction: A systematic review and meta-analysis

AIM

The aim of this systematic review was to critically analyse the available evidence on the effect of different modalities of alveolar ridge preservation (ARP) as compared to tooth extraction alone in function of relevant clinical, radiographic and patient-centred outcomes.

MATERIAL AND METHODS

A comprehensive search aimed at identifying pertinent literature for the purpose of this review was conducted by two independent examiners. Only randomized clinical trials (RCTs) that met the eligibility criteria were selected. Relevant data from these RCTs were collated into evidence tables. Endpoints of interest included clinical, radiographic and patient-reported outcome measures (PROMs). Interventions reported in the selected studies were clustered into ARP treatment modalities. All these different ARP modalities were compared to the control therapy (i.e. spontaneous socket healing) in each individual study after a 3- to 6-month healing period. Random-effects meta-analyses were conducted if at least two studies within the same ARP treatment modality reported on the same outcome of interest.

RESULTS

A combined database, grey literature and hand search identified 3,003 records, of which 1,789 were screened after removal of duplicates. Following the application of the eligibility criteria, 25 articles for a total of 22 RCTs were included in the final selection, from which nine different ARP treatment modalities were identified: (a) bovine bone particles (BBP) + socket sealing (SS), (b) construct made of 90% bovine bone granules and 10% porcine collagen (BBG/PC) + SS, (c) cortico-cancellous porcine bone particles (CPBP) + SS, (d) allograft particles (AG) + SS, (e) alloplastic material (AP) with or without SS, (f) autologous blood-derived products (ABDP), (g) cell therapy (CTh), (h) recombinant morphogenic protein-2 (rhBMP-2) and (i) SS alone. Quantitative analyses for different ARP modalities, all of which involved socket grafting with a bone substitute, were feasible for a subset of clinical and radiographic outcomes. The results of a pooled quantitative analysis revealed that ARP via socket grafting (ARP-SG), as compared to tooth extraction alone, prevents horizontal (M = 1.99 mm; 95% CI 1.54-2.44; p < 0.00001), vertical mid-buccal (M = 1.72 mm; 95% CI 0.96-2.48; p < 0.00001) and vertical mid-lingual (M = 1.16 mm; 95% CI 0.81-1.52; p < 0.00001) bone resorption. Whether there is a superior ARP or SS approach could not be determined on the basis of the selected evidence. However, the application of particulate xenogenic or allogenic materials covered with an absorbable collagen membrane or a rapidly absorbable collagen sponge was associated with the most favourable outcomes in terms of horizontal ridge preservation. A specific quantitative analysis showed that sites presenting a buccal bone thickness >1.0 mm exhibited more favourable ridge preservation outcomes (difference between ARP [AG + SS] and control = 3.2 mm), as compared to sites with a thinner buccal wall (difference between ARP [AG + SS] and control = 1.29 mm). The effect of other local and systemic factors could not be assessed as part of the quantitative analyses. PROMs were comparable between the experimental and the control group in two studies involving the use of ABDP. The effect of other ARP modalities on PROMs could not be investigated, as these outcomes were not reported in any other clinical trial included in this study.

CONCLUSION

Alveolar ridge preservation is an effective therapy to attenuate the dimensional reduction of the alveolar ridge that normally takes place after tooth extraction.

Myofibroblast Gene Expression Profile after Tooth Extraction in the Rabbit

After tooth extraction, the alveolar bone tends to shrink in volume, especially on the vestibular side. The role of myofibroblasts in bone remodeling has not been sufficiently investigated. The aim of the present study was to explore the gene expression related to myofibroblasts presence and activity during a 90-day healing period after tooth extraction. The study included 36 rabbits, and a single tooth extraction was performed on each rabbit. The extractive sockets were randomly distributed to natural healing or to scarification of the wound. The sacrifices were staggered in such a manner that animals contributed with sockets representing 2, 7, 15, 30, 60, and 90 days of healing. Nanostring technology was used to evaluate the expression of a wide panel consisting in 148 genes related to the activation, induction, and suppression of myofibroblasts, socket microenvironment, and autophagy. We found that the expression profile of this custom panel was time-related. The post-extractive socket was subjected to significant gene expression changes after 15 days: the genes involved in the induction of myofibroblasts were up-regulated in the first 15-day period and down-regulated during the rest of the follow-up. The study suggested that myofibroblasts play a major role in the immediate 15-day period following tooth extraction.

Extraction Socket Preservation with or without Membranes, Soft Tissue Influence on Post Extraction Alveolar Ridge Preservation: a Systematic Review

Objectives

The purpose of this systematic review was to assess quantitatively and qualitatively the influence of two different factors: membranes and soft tissue graft influence for the extraction socket preservation.

Material and Methods

A wide-ranging electronic search was performed in six databases up to 30 of November 2018 in order to identify all the clinical and randomized clinical trials performed in humans published with no data restriction. The inclusion criteria were extraction socket preservation with and without membranes or a soft tissue graft in a intact socket with at least six months of follow-up, have more than 12 patients or treat more than 12 sites per group and evaluated at least one of the primary outcomes measures (radiographic measures histological assessment, clinical measures).

Results

From an initial search of 1524 studies only 6 papers fulfil the inclusion and exclusion criterions. All the six selected papers, presented a wide heterogeneity of treatments used, evaluated variables and observation period that made impossible to recommend any specific techniques and/or material to achieve better results. The limited data found suggest that the used of membrane reveals to achieve better results. It wasn’t possible to observe in any clinical trial that compares the used of soft tissue graft.

Conclusions

New trials need to be performed in order to identify what specific techniques and/or materials are better to decrease the reabsorption of the socket after tooth extraction. Clinical trials designed to understand when/how the soft tissues grafts influence at the socket preservation is needed.

Dimensional changes following alveolar ridge preservation in the posterior area using bovine-derived xenografts and collagen membrane compared to spontaneous healing: a 6-month randomized controlled clinical trial

OBJECTIVES

To assess dimensional changes following alveolar ridge preservation using bovine-derived xenograft with 10% collagen and collagen membrane compared to ridge preservation by means of bovine-derived xenograft particles and collagen membrane or spontaneous healing in posterior sites.

MATERIALS AND METHODS

Forty subjects with 40 posterior teeth or roots candidate to extraction and presenting integrity of alveolar bone walls were randomly allocated into three groups. Patients of test group were treated by ridge preservation technique using bovine-derived xenograft with 10% collagen and collagen membrane; patients of control group 1 were treated by means of bovine-derived xenograft particles and collagen membrane while in patients of control group 2, no grafting was performed. Changes in vertical and horizontal bone dimensions were compared at baseline and after 6-month observation time.

RESULTS

Statistically significant differences between baseline and 6 month were observed in all groups in terms of vertical and horizontal bone resorption (p < 0.001), except for vertical resorption in control group 2. After 6-month intergroup comparisons showed not statistically significant changes between test and control groups in terms of alveolar bone changes (p > 0.05).

CONCLUSIONS

Within the limits of this study, the sites grafted using bovine-derived xenograft with 10% collagen in combination with a collagen membrane showed no statistical differences in terms of vertical and horizontal bone resorption compared to control groups.

CLINICAL RELEVANCE

Ridge preservation in posterior area failed to show clinically relevant benefits in sites presenting integrity of alveolar bone walls and adequate buccal bone wall thickness.

Human Gingival Fibroblasts Exposed to Extremely Low-Frequency Electromagnetic Fields: In Vitro Model of Wound-Healing Improvement

Several clinical studies have suggested the impact of sinusoidal and pulsed electromagnetic fields in quickening wound repair processes and tissue regeneration. The clinical use of extremely low-frequency electromagnetic fields could represent a novel frontier in tissue repair and oral health, with an interesting clinical perspective. The present study aimed to evaluate the effect of an extremely low-frequency sinusoidal electromagnetic field (SEMF) and an extremely low-frequency pulsed electromagnetic field (PEMF) with flux densities of 1 mT on a model of oral healing process using gingival fibroblasts. An in vitro mechanical injury was produced to evaluate wound healing, migration, viability, metabolism, and the expression of selected cytokines and protease genes in fibroblasts exposed to or not exposed to the SEMF and the PEMF. Interleukin 6 (IL-6), transforming growth factor beta 1 (TGF-β), metalloproteinase 2 (MMP-2), monocyte chemoattractant protein 1 (MCP-1), inducible nitric oxide synthase (iNOS), and heme oxygenase 1 (HO-1) are involved in wound healing and tissue regeneration, favoring fibroblast proliferation, chemotaxis, and activation. Our results show that the exposure to each type of electromagnetic field increases the early expression of IL-6, TGF-β, and iNOS, driving a shift from an inflammatory to a proliferative phase of wound repair. Additionally, a later induction of MMP-2, MCP-1, and HO-1 was observed after electromagnetic field exposure, which quickened the wound-healing process. Moreover, electromagnetic field exposure influenced the proliferation, migration, and metabolism of human gingival fibroblasts compared to sham-exposed cells. This study suggests that exposure to SEMF and PEMF could be an interesting new non-invasive treatment option for wound healing. However, additional studies are needed to elucidate the best exposure conditions to provide the desired in vivo treatment efficacy.

Anti-resorptive effect of pamidronate on extraction socket wall in dogs

AIM

The aim of this experimental in vivo investigation was to assess the anti-resorptive effect of low concentration pamidronate on the buccal plate in fresh extraction sockets.

MATERIALS AND METHODS

The distal roots of the third premolars were extracted bilaterally in six dogs. A collagen matrix loaded with either pamidronate (test group) or saline (control group) was positioned on the outer surface of buccal bone immediately after tooth extraction and subsequently covered with a coronally advanced flap. Histological and histomorphometric outcomes were evaluated 12 weeks later.

RESULTS

The mean vertical distance between the buccal and lingual bone crest differed significantly between the test and control groups (0.52 ± 0.43 and 2.21 ± 1.15 mm, respectively; p = .037). The width of the buccal bone 1 mm below the crest was significantly wider in the test group than the control group (4.68 ± 0.68 vs. 3.44 ± 0.60 mm, p < .001).

CONCLUSIONS

Local application of pamidronate onto a collagen matrix may reduce the dimensional changes of the buccal bone plate both vertically and horizontally.

Trabecular bone microstructure and mineral density in human residual ridge at various intervals over a long period after tooth extraction

BACKGROUND

Long-term changes of trabecular microstructure in human tooth extraction socket have not been investigated.

PURPOSE

To examine the trabecular microstructure of human residual ridges at various intervals following tooth extraction, and to determine whether bone remodeling activity can attain points of relative stability and when such points are reached.

MATERIALS AND METHODS

Forty-four bone biopsy specimens were obtained from lower molar or premolar regions of residual ridges. Postextraction times ranged from 1.6 to 360 months. Samples were analyzed using micro-computed tomography and three-dimensional bone morphometry with histological analyses. Trabecular bone parameters were plotted against postextraction times, and a stepwise piecewise linear regression analysis was performed to determine at which points of time these parameters either increased or decreased.

RESULTS

Using piecewise linear regression, "inflection points" were found in most trabecular bone parameters between 7 and 12 months postextraction. Among the residual ridge samples, woven trabecular structure became mature, consisting of thick lamellar trabeculae with sufficient bone density, under dynamic bone remodeling until the 7th to 12th month post-tooth extraction. After this period, the mature network structure remained stable with low remodeling activity.

CONCLUSION

Bone remodeling of trabecular structure in human residual ridge after tooth extraction had a stabilization period.

Evaluation of dimensional behavior of peri-implant tissues in implants immediately exposed or submerged in fresh extraction and healed sites: a histological study in dogs

Background

The aim of this study was to compare histologically the dimensional behavior of peri-implant tissues during osseointegration of immediately exposed or submerged implant placement in fresh extraction and healed sites.

Methods

Four fresh extraction and four delayed implant sites were placed in each hemimandible of five dogs at the bone crest level. In 2 implants of each side were installed a healing abutment (exposed) and two cover screw (submerged) and formed four groups: implant installed in fresh extraction submerged (group 1), implants in fresh extraction immediately exposed (group 2), implants installed in healed site submerged (group 3), and implants in healed site immediately exposed (group 4). After 12 weeks of healing period, histomorphometric analyses of the specimens were carried out to measure the crestal bone level values and the tissue thickness in the implant shoulder portion.

Results

The measure of crestal bone level showed some higher values for implants installed in fresh extraction sites in the buccal aspect: 1.88 ± 0.42 mm for group 1 and 2.33 ± 0.33 mm for group 2, with statistical significance among all four groups tested (P < 0.001). For peri-implant tissue thickness, a significative higher statistical difference (P < 0.001) for implants installed in healed sites (groups 3 and 4) was found.

Conclusions

Within the limitations of the present animal study, our findings suggest that the implants placed in fresh extraction or healed site and with regards to the moment of exposition (immediately or no) are important factors to the amount of peri-implant tissues after remodeling over a period of 12 weeks. The null hypothesis was rejected.

Wound Healing Problems in the Mouth

Wound healing is a primary survival mechanism that is largely taken for granted. The literature includes relatively little information about disturbed wound healing, and there is no acceptable classification describing wound healing process in the oral region. Wound healing comprises a sequence of complex biological processes. All tissues follow an essentially identical pattern to complete the healing process with minimal scar formation. The oral cavity is a remarkable environment in which wound healing occurs in warm oral fluid containing millions of microorganisms. The present review provides a basic overview of the wound healing process and with a discussion of the local and general factors that play roles in achieving efficient would healing. Results of oral cavity wound healing can vary from a clinically healed wound without scar formation and with histologically normal connective tissue under epithelial cells to extreme forms of trismus caused by fibrosis. Many local and general factors affect oral wound healing, and an improved understanding of these factors will help to address issues that lead to poor oral wound healing.

Can Time of Implant Placement influence Bone Remodeling?

Since the alveolar process is tissue "dental dependent," after the extraction of the dental element, this process suffers some degree of atrophy during the healing process, which can be reduced with the installation of immediate implants, aiming to maintain the original bone architecture. The aim of this study was to investigate the influence of the time of implant placement on bone formation around them. Seven dogs were selected and randomly divided into two groups: Group 1, where implants were placed immediately after extraction of two lower premolars without flap elevation, and group 2, where implants were delayed by 4 months after extractions. Each group received 14 implants, and 4 months after the second surgery, the samples were processed and analyzed histomorphometrically. A mean average analysis and the Kruskal-Wallis test (p < 0.05) were performed. The buccal bone-implant contact (BIC) mean average was found larger in immediate implants (42.61%) compared with delayed implants (37.69%). Group 1 had statistically higher outcomes in bone formation and BIC on the buccal bone wall. It was concluded that performing immediate implants with the palatal approach technique and leaving a buccal GAP enables a higher or at least equal rate to BIC and bone area around them, when compared with delayed implants. Actually, the patients and dentists want to do a shorter treatment with satisfactory results, but it is necessary to understand whether different times of implant placement can influence the results and longevity of the treatment.

Intramembranous bone healing process subsequent to tooth extraction in mice: micro-computed tomography, histomorphometric and molecular characterization

Bone tissue has a significant potential for healing, which involves a significant the interplay between bone and immune cells. While fracture healing represents a useful model to investigate endochondral bone healing, intramembranous bone healing models are yet to be developed and characterized. In this study, a micro-computed tomography, histomorphometric and molecular (RealTimePCRarray) characterization of post tooth-extraction alveolar bone healing was performed on C57Bl/6 WT mice. After the initial clot dominance (0h), the development of a provisional immature granulation tissue is evident (7d), characterized by marked cell proliferation, angiogenesis and inflammatory cells infiltration; associated with peaks of growth factors (BMP-2-4-7,TGFβ1,VEGFa), cytokines (TNFα, IL-10), chemokines & receptors (CXCL12, CCL25, CCR5, CXCR4), matrix (Col1a1-2, ITGA4, VTN, MMP1a) and MSCs (CD105, CD106, OCT4, NANOG, CD34, CD146) markers expression. Granulation tissue is sequentially replaced by more mature connective tissue (14d), characterized by inflammatory infiltrate reduction along the increased bone formation, marked expression of matrix remodeling enzymes (MMP-2-9), bone formation/maturation (RUNX2, ALP, DMP1, PHEX, SOST) markers, and chemokines & receptors associated with healing (CCL2, CCL17, CCR2). No evidences of cartilage cells or tissue were observed, strengthening the intramembranous nature of bone healing. Bone microarchitecture analysis supports the evolving healing, with total tissue and bone volumes as trabecular number and thickness showing a progressive increase over time. The extraction socket healing process is considered complete (21d) when the dental socket is filled by trabeculae bone with well-defined medullary canals; it being the expression of mature bone markers prevalent at this period. Our data confirms the intramembranous bone healing nature of the model used, revealing parallels between the gene expression profile and the histomorphometric events and the potential participation of MCSs and immune cells in the healing process, supporting the forthcoming application of the model for the better understanding of the bone healing process.

Post-extraction evaluation of sockets with one plate loss--a microtomographic and histological study

AIM

The aim of this study is to evaluate the characteristics of socket repair after teeth extraction with loss of a bone plate.

MATERIAL AND METHOD

Lower incisors were extracted from 120-day-old male rabbits. A standardized defect of 5 mm in the buccal plate was created in one of the socket sites. Furthermore, complete closures of the sockets entrance were performed. Two groups of biopsies were obtained: one with 14 days of healing and the other with 112, to perform the micro-CT and histological evaluations of the tested group with plate loss comparing with the control group with the intact buccal bone wall.

RESULTS

Plate loss sites demonstrated reduction in width when compared to the intact ones and, this difference decreased with time.

CONCLUSION

Long-term analysis showed that plate loss interfered in final ridge measurements by reducing the middle portion of the socket width compared to the intact plate sockets. The histological and micro-CT qualitative analysis showed that both sites presented similar pattern of healing, despite the reduced dimension found in plate loss sites.