SDF-1 involvement in orthodontic tooth movement after tooth extraction

The stromal cell-derived factor 1 (SDF-1)/chemokine receptor type 4 (CXCR4) axis plays a key role in alveolar bone metabolism during orthodontic tooth movement (OTM). Herein, the effects of the SDF-1/CXCR4 axis on the regional acceleratory phenomenon (RAP) in OTM velocity and on changes in the surrounding periodontium after adjacent tooth extraction in rats were investigated. Six-week-old male Wistar/ST rats underwent left maxillary first molar (M1) extraction and mesial OTM of the left maxillary second molar (M2) with a 10-g force closed-coil spring. Phosphate-buffered saline, immunoglobulin G (IgG) isotype control antibody, or anti-SDF-1 neutralizing monoclonal antibody were injected at the M1 and M2 interproximal areas (10 μg/0.1 mL) for the first three days. Analyses were performed after 1, 3, and 7 days (n = 7). The results demonstrated a significant increase in SDF-1 expression from day 1, which was effectively blocked via anti-SDF-1 neutralizing monoclonal antibody injection. On day 3, the M2 OTM distance and the number of positively stained osteoclasts significantly reduced alongside a reduction in inflammatory markers in the experimental group. Our results demonstrated that serial local injection of the anti-SDF-1 neutralizing monoclonal antibody reduces M2 OTM, osteoclast accumulation, and localized inflammatory responses in an OTM model with tooth extraction-induced RAP.

Effects of blue-light LED toothbrush on reducing dental plaque and gingival inflammation in orthodontic patients with fixed appliances: a crossover randomized controlled trial

BACKGROUND

Patients with fixed orthodontic appliances have higher plaque accumulation and gingival inflammation. Our aim was to compare the effectiveness of a light emitting diode (LED) toothbrush with a manual toothbrush in reducing dental plaque and gingival inflammation in orthodontic patients with fixed appliances, and to investigate the effect of the LED toothbrush on Streptococcus mutans (S. mutans) biofilm in vitro.

METHODS

Twenty-four orthodontic patients were recruited and randomly assigned into 2 groups: (1) started with manual and (2) started with LED toothbrushes. After a 28-day usage and 28-day wash-out period, the patients switched to the other intervention. The plaque and gingival indices were determined at baseline and 28 days after each intervention. The patients' compliance and satisfaction scores were collected using questionnaires. For the in vitro experiments, S. mutans biofilm was divided into 5 groups (n = 6) with 15-, 30-, 60-, or 120-sec LED exposure, and without LED exposure as a control group.

RESULTS

There was no significant difference in the gingival index between the manual and LED toothbrush groups. The manual toothbrush was significantly more effective in reducing the plaque index in the proximal area on the bracket side (P = 0.031). However, no significant difference was found between the two groups in other areas around the brackets or on the non-bracket side. After LED exposure in vitro, the percentages of bacterial viability after LED exposure for 15-120 s were significantly lower compared with the control (P = 0.006).

CONCLUSION

Clinically, the LED toothbrush was not more effective in reducing dental plaque or gingival inflammation than the manual toothbrush in orthodontic patients with fixed appliances. However, the blue light from the LED toothbrush significantly reduced the number of S. mutans in biofilm when it was exposed to the light for at least 15 s in vitro.

CLINICAL TRIAL REGISTRATION

Thai Clinical Trials Registry (TCTR20210510004). Registered 10/05/2021.

Vowel sound production and its association with cephalometric characteristics in skeletal Class III subjects

BACKGROUND

This study aimed to evaluate differences in vowel production using acoustic analysis in skeletal Class III and Class I Japanese participants and to identify the correlation between vowel sounds and cephalometric variables in skeletal Class III subjects.

MATERIALS AND METHODS

Japanese males with skeletal Class III (ANB < 0°) and Class I skeletal anatomy (0.62° < ANB < 5.94°) were recruited (n = 18/group). Acoustic analysis of vowel sounds and cephalometric analysis of lateral cephalograms were performed. For sound analysis, an isolated Japanese vowel (/a/,/i/,/u/,/e/,/o/) pattern was recorded. Praat software was used to extract acoustic parameters such as fundamental frequency (F0) and the first four formants (F1, F2, F3, and F4). The formant graph area was calculated. Cephalometric values were obtained using ImageJ. Correlations between acoustic and cephalometric variables in skeletal Class III subjects were then investigated.

RESULTS

Skeletal Class III subjects exhibited significantly higher/o/F2 and lower/o/F4 values. Mandibular length, SNB, and overjet of Class III subjects were moderately negatively correlated with acoustic variables.

LIMITATIONS

This study did not take into account vertical skeletal patterns and tissue movements during sound production.

CONCLUSION

Skeletal Class III males produced different /o/ (back and rounded vowel), possibly owing to their anatomical positions or adaptive changes. Vowel production was moderately associated with cephalometric characteristics of Class III subjects. Thus, changes in speech after orthognathic surgery may be expected. A multidisciplinary team approach that included the input of a speech pathologist would be useful.

The association between thread pitch and cortical bone thickness influences the primary stability of orthodontic miniscrew implants: a study in human cadaver palates

OBJECTIVE

The purpose of this study was to mathematically evaluate the influence of variations in thread pitch and cortical bone thickness on the maximum insertion torque (MIT) and implant stability (IS) of miniscrew implants (MIs).

METHODS

Sixty custom made MIs with a 0.4-, 0.6-, 0.8-, 1.0-, or 1.2-mm thread pitch,12 for each pitch, were randomly placed into the palates of 10 embalmed human maxillae. The MIT was measured with a hand-operated digital torque reader screwdriver with a holding guide, and the IS test was performed using Anycheck. Conebeam computerized tomography was used to measure the cortical bone thickness(CBT) at each MI site. One-way ANOVA, Tukey post hoc test, Pearson's correlation,and multiple linear regression models were performed using the SPSS program.

RESULTS

The MIT and IS tests demonstrated a pitch-dependent decrease. The pitch had a strong negative correlation with MIT and IS, while the CBT had a strong positive correlation with those outcomes. The association between pitch and CBT significantly influenced MI primary stability. Moreover, a strong correlation was found between MIT and IS.

CONCLUSIONS

The MI primary stability, MIT, and IS are strongly influenced by theassociation between MI thread pitch and CBT.

Cytotoxicity, genotoxicity, and cellular metal accumulation caused by professionally applied fluoride products in patients with fixed orthodontic appliances: A randomized clinical trial

BACKGROUD

Corrosion of metal orthodontic appliances caused by professional fluoride products has been recently concerned. Therefore, the objective of this study was to evaluate the cytotoxic and genotoxic effect of these products on buccal mucosal cells from patients wearing fixed orthodontic appliances.

METHODS

A total of 44 patients, aged 12 to 35 years, who began orthodontic treatment with fixed appliances were included in this single-center, prospective, randomized clinical trial. Patients were randomly allocated into 4 parallel groups according to the type of professional fluoride treatment applied after placing the appliances: acidulated phosphate fluoride gel (APF); neutral fluoride gel (NGel); fluoride varnish (FVa); and without fluoride treatment (control). Buccal cells were collected before treatment (T1) and 3 months after appliance placement (T2). The cells were assayed for cell viability and underwent Papanicolaou staining. Cells with micronuclei and degenerative nuclear alterations were scored using a light microscope. Cell metal content was quantified by inductively coupled plasma-mass spectrometry. The data were analyzed with the Kruskal-Wallis test.

RESULTS

The intracellular nickel content in the APF group significantly increased (P < 0.05), whereas that of the control, NGel, and FVa groups did not. The changes in chromium concentration in all groups were not significantly different compared with control. Use of APF resulted in a significantly higher decrease in cell viability and increase in morphologic signs of cell death compared with control (P < 0.05). The change in frequency of micronucleated cells was not significantly different from that in the control group.

CONCLUSIONS

Applying APF gel on fixed orthodontic appliances increased the cell metal content and decreased cell viability; however, genotoxic effects were absent. FVa and NGel are suggested as the products of choice to use during orthodontic treatment.

Exposure to the oral environment enhances the corrosion of metal orthodontic appliances caused by fluoride-containing products: Cytotoxicity, metal ion release, and surface roughness

INTRODUCTION

This study aimed to evaluate the metal ion release, cytotoxicity, and surface roughness of clinically used metal orthodontic appliances after immersion in different fluoride product solutions compared with those of new appliances.

METHODS

Used fixed appliances were debonded from 36 patients after their treatment was done. New appliances were as-received. Each used and new group comprised 36 sets of 20 brackets and 4 tubes that were divided into 3 groups by archwire type; stainless steel, nickel-titanium, and beta-titanium. The samples in each group were divided into 3 subgroups and immersed in solutions of fluoride toothpaste, 1.23% acidulated phosphate fluoride, or artificial saliva without fluoride as a control group. The immersion times were estimated from the recommended time for using each fluoride product for 3 months. The samples were then immersed in Dulbecco's Modified Eagle's Medium for 7 days. The cytotoxicity test was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay using primary gingival fibroblasts. Chromium, nickel, and iron ion release were detected using inductively coupled plasma mass spectroscopy. The surface roughness of the brackets and wires was measured by a scanning electron microscope and a noncontact optical 3-dimensional surface characterization and roughness measuring device. The data were analyzed using the paired t test and 2-way analysis of variance.

RESULTS

Used brackets demonstrated a significantly higher ion release, surface roughness, and cytotoxicity than the new brackets. Acidulated phosphate fluoride significantly increased the ion release and surface roughness; however, it significantly decreased cell viability, especially in the titanium molybdenum subgroup.

CONCLUSIONS

Used brackets were significantly prone to further corrosion. Acidulated phosphate fluoride gel should not be used in orthodontic patients with fixed metal appliances.

Age-related dental phenotypes and tooth characteristics of FAM83H-associated hypocalcified amelogenesis imperfecta

OBJECTIVES

Autosomal-dominant hypocalcified amelogenesis imperfecta (ADHCAI) shows phenotypic heterogeneity. Our aim was to characterise the ADHCAI phenotypes, tooth properties and genotypes.

METHODS

Three unrelated ADHCAI probands and seven additional affected members of the three families were recruited. Mutations were identified by exome and Sanger sequencing, and haplotypes by SNP array. Tooth colour, roughness, density, nanohardness, minerals and ultrastructure were investigated.

RESULTS

Ten participants were heterozygous for the FAM83H mutation c.1387C>T (p.Gln463*). All shared a 3.43 Mbp region on chromosome 8q24.3 encompassing the FAM83H variant, indicating a common ancestry. The c.1387C>T was estimated to be 23.8 generations or 600 years. The FAM83H enamel had higher roughness and lower lightness, density, nanohardness, and calcium and phosphorus levels than controls. Blunted enamel rods, wide interrod spaces and disorganised dentinoenamel junctions were observed. Evaluating the patients with the same mutation and reviewing others with different mutations in FAM83H revealed that the FAM83H heterogeneous phenotypes are age-influenced. Tooth colour and surface texture change with ageing.

CONCLUSIONS

FAM83H enamel demonstrated decreased lightness, density, hardness, calcium, phosphorus and defective ultrastructure. We have identified that the phenotypic variation in FAM83H-associated ADHCAI is age-related. Awareness of the correlation between age and clinical features of FAM83H-ADHCAI can help dentists make an accurate diagnosis.