Polygraphic evaluation of the effects of different rapid maxillary expansion appliances on sleep quality: A randomized clinical trial.

BACKGROUND: The purpose of this clinical study was to assess the effects of different rapid maxillary expansion appliances on the severity of obstructive sleep apnea (OSA). MATERIAL AND METHODS: Patients having a narrow maxilla and identified with OSA were divided randomly into three groups: tooth tissue-borne, tooth-borne, and bone-borne expanders. Changes in sleep parameters at baseline and 3-month follow-up detected by polygraphy were the primary outcome. Treatment of the crossbite was the secondary outcome. Dunn-Bonferroni tests, Kruskal-Wallis, and Wilcoxon analysis were applied for intra- and inter-group differences at p < 0.05 significance level. RESULTS: Among 46 patients randomized, apnea-hypopnea index (AHI) changed from baseline to follow-up in all groups (- 1.6, p = 0.280; 0.6, p = 0.691; - 0.45, p = 0.796, respectively), with no between-group difference (p = 0.631). Oxygen desaturation index (ODI) altered from baseline to follow-up in all groups (0.80, p = 0.977; 0.20, p = 0.932; and - 1.00, p = 0.379, respectively), with no between-group difference (p = 0.858). There was no significant difference in minimum oxygen saturation from baseline to follow-up in all groups (0.00, p = 0.401; - 2.00, p = 0.887; 0.50, p = 0.407, respectively). No significant changes were observed in supine AHI from baseline to follow-up in all groups (0.00, p = 0.581; - 1.00, p = 0.393; 0.00, p = 0.972, respectively). The upper intermolar width increased from baseline to follow-up in all groups (5.04, p = 0.000; 3.15, p = 0.001; 5.41, p = 0.00, respectively) with no between-group difference (p = 0.560). Maxillary width increased from baseline to follow-up in all groups (4.25, p = 0.001; 4.74, p = 0.00; 4.49, p = 0.001, respectively) with no inter-group difference (p = 0.963). CONCLUSIONS: The amount of skeletal and dental expansion obtained in the maxilla was similar in all groups. Rapid maxillary expansion was not found to be effective in OSA treatment. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04604392.

Evaluating the effects of orthodontic treatment with clear aligners and conventional brackets on mandibular condyle bone quality using fractal dimension analysis of panoramic radiographs.

OBJECTIVE: Orthodontic treatment carried out with clear aligners has become a method that is preferred by patients. In this study, the effect following orthodontic treatment with clear aligners and with conventional brackets, on the mandibular condyle trabecular bone formation is aimed to be examined. MATERIALS AND METHODS: Thirty two individuals (16 females and 16 males) with a mean age of 16.80 ± 3,10 years who received orthodontic treatment with clear aligners and conventional brackets were included in the study. Individuals included in the study from the archive data were divided into two groups according to treatment types. The mandibular condyle bone quality in the panoramic images taken from the patients before orthodontic treatment (T0) and after orthodontic treatment (T1) has been compared retrospectively. This examination is carried out via the fractal analysis method. RESULT: The mandibular condyle bone density in individuals that have undergone orthodontic treatment with clear aligners, has been reduced following orthodontic treatment. In individuals that have undergone orthodontic treatment with conventional brackets however the mandibular condyle bone density has increased following treatment (T0) in comparison to before being treated (T1). The mandibular condyle bone density change according to different treatment groups has been found to be statistically different. CONCLUSION: Orthodontic treatment with clear aligners provides several advantages to patients. However, besides determining the effectiveness of the treatment, complications must also be examined. Application of clear aligners in orthodontic treatment may cause a decrease in bone density in the mandibular condyle. When evaluating orthodontic treatments carried out with clear aligners, the change of the mandibular condyle head bone should be taken into consideration.

Evaluation of the effects of different rapid maxillary expansion appliances on airway by acoustic rhinometry: A randomized clinical trial.

OBJECTIVE: The purpose of this 3-arm parallel trial was to compare the effects of tooth tissue-borne (TTB), tooth-borne (TB) and bone-borne (BB) rapid maxillary expansion (RME) appliances on nasal airway with acoustic rhinometry (AR). SETTING AND SAMPLE POPULATION: Forty-six 12- to 14-year-old patients with narrow maxilla were randomly allocated into 3 study groups accordingly the type of expander: TTB, TB and BB. The participants were recruited from the Department of Orthodontics, Izmir Katip Celebi University. MATERIALS AND METHODS: All patients had RME with an initial activation of two-quarter turns a day (0.5 mm) for an average of 8 days followed by 1 quarter turns per day for an average of 10 days. Disguised group allocation using opaque sealed envelopes was made with a computer-generated randomization program. The primary outcome was changes on the minimal nasal cross-sectional area (MCA). Secondary outcome included the assessment of nasal cavity volume. AR measurements were obtained at baseline (T0), immediately after the expansion (T1), and at 3 months-follow-up (T2). One-way analysis of variance (ANOVA) and Bonferroni test were used for inter-group comparison and two-way ANOVA was used for intra-group evaluation. RESULTS: There were significant increases in MCA 1, 2 and nasal Vol in all groups after the treatment (95% [CI], P < 0.05) whereas in inter-group comparisons; MCA 1, 2 and nasal Vol, the changes were found to be similar (95% [CI], P > 0.05). HARMS: No serious harm was observed except for mild gingivitis due to plaque accumulation. CONCLUSIONS: RME treatment increased minimal nasal cross-sectional areas and nasal volume irrespective of appliance design. TRIAL REGISTRATION: This trial was registered at Clinicaltrials.gov (Identifier NCT04529057). PROTOCOL: The protocol was not published. FUNDING: This trial was financed by Izmir Katip Celebi University, Scientific Research Projects Unit [grant number 2016-TDR-SABE-0024].

Tooth-borne versus tooth-bone-borne rapid maxillary expanders according to a stereophotogrammetric evaluation of facial soft tissues: A randomized clinical trial.

OBJECTIVES: To evaluate the effects of tooth-borne and tooth-bone-borne rapid maxillary expansion (RME) on soft tissue with stereophotogrammetry. SETTING AND SAMPLE POPULATION: Thirty two patients (15 males and 17 females) who met inclusion criteria were divided into two groups. In the first group, tooth-borne RME appliance (hyrax) was applied to 16 patients (9 males and 7 females mean age 13.4 ± 1.3 years), and in the second group, tooth-bone-borne RME appliance (hybrid hyrax) was applied to 16 patients (6 males and 10 females, mean age 13.05 ± 1.24 years). MATERIALS AND METHODS: Changes in soft tissues before RME (T0) and post-retention (T1) period were evaluated by stereophotogrammetry. Linear and angular measurements were performed. Independent- and dependent-sample t tests were used to compare intra- and inter-group differences at P < .05 significance level. RESULTS: The data revealed statistically significant changes in nasal width, mid-face width, upper lip vermillion length/lower lip vermillion length ratio and upper lip angle in hyrax group. (P < .05) Also nasal width, lower lip length, lower lip vermillion length, anterior face height, lower face height, convexity angle and mandibular angle showed statistically significant changes in hybrid hyrax group. (P < .05) In the inter-group evaluation, no significant differences were found except upper lip and mandible angle. (P < .05). CONCLUSION: Both hyrax and hybrid hyrax expanders had effects on soft tissue profile. Anterior face height and lower face height increased in both groups. Upper lip length increased by 0.36 mm in the hybrid group and 0.10 mm in the hyrax group. TRIAL REGISTRATION: This trial was registered at Clinicaltrials.gov (Identifier: NCT04828213).

A postero-anterior cephalometric evaluation of different rapid maxillary expansion appliances.

BACKGROUND: The purpose of the study was to evaluate dental and skeletal changes induced by tooth-bone-borne, tooth-tissue-borne, and tooth-borne rapid maxillary expansion (RME) appliances using postero-anterior (PA) cephalometric radiographs. METHODS: A total of 54 patients' (25 boys, 29 girls) PA cephalometric radiographs who had bilateral posterior crossbite and RME treatment were included and divided into three groups according to the type of appliance used during treatment: tooth-bone-borne RME appliance (hybrid Hyrax) (7 boys, 11 girls, mean age 13.28 ± 1.20 years), tooth-tissue-borne RME appliance (TTB) (8 boys, 10 girls, mean age 13.08 ± 1.06 years) and tooth-borne RME appliance (Hyrax) (10 boys, 8 girls, mean age 12.05 ± 1.35 years). Pretreatment (T0) and posttreatment (T1) PA cephalometric radiographs were analyzed with Dolphin software v. 11.7 (Chatsworth, CA). The comparisons of the groups were performed with Two-way analysis of variance. P < 0.05 was considered statistically significant. RESULTS: Significant and equal increase of right molar relationship and upper intermolar molar widths occurred in all groups. Dental midline discrepancy showed significant increase in only hybrid Hyrax group between T0 and T1. Significant increases were reported for lateronasal width in hybrid Hyrax and tooth-tissue-borne groups (P < 0.05). CONCLUSIONS: Both skeletal and dental changes were observed after RME in all groups. However, the greatest skeletal changes were seen in hybrid Hyrax and tooth-tissue-borne groups.

Evaluation of soft-tissue changes in young adults treated with the Forsus fatigue-resistant device.

INTRODUCTION: This study aimed to evaluate the effects of the Forsus fatigue-resistant device (FRD) EZ2 appliance (3M Unitek, Monrovia, Calif) on facial soft tissues by using images obtained from cephalometric radiographs and 3-dimensional (3D) facial scanning system. METHODS: A total of 20 patients treated with the Forsus FRD EZ2 appliance were included in this study. The cervical vertebral maturation index was used to determine growth and development stages, and the subjects were investigated at cervical vertebral maturation stages 5 and 6 (ie, postpeak period). Three-dimensional facial scanning images were obtained with 3dMD Face (3dMD Ltd, Atlanta, Ga). Cephalometric radiographic images were taken before placement of the appliance (T0), immediately after removal (T1), and at the 6-month (T2) follow-up after the removal of the appliance. For comparison of the data, one-way repeated-measures analysis of variance and paired t test were used at P < 0.05. RESULTS: Statistically significant changes were found in the Wits value, IMPA, L1P-NB (°), L1-NB (mm), L1P-APog, U1P-L1P, overjet, overbite, Ls-E, and labiomental angle in T0-T1. In T0-T2, statistically significant changes in the Wits, IMPA, L1P-NB (°), overjet, overbite and Ls-E values were observed. CONCLUSIONS: The results revealed that the correction of malocclusion with Forsus FRD EZ2 appliance in patients at the postpeak period was mainly dentoalveolar. The soft tissues were affected to a limited extent. Three-dimensional facial scanning demonstrated similar accuracy and precision to traditional cephalometry, being a repeatable and accurate tool for linear and surface measurements.

Efficiency evaluation of rapid maxillary expansion treatment on nasal septal deviation using tortuosity ratio from cone-beam computer tomography images.

BACKGROUND AND OBJECTIVE: This study aims to assess the effect of Rapid Maxillary Expansion (RME) on Nasal Septal Deviation (NSD) changes from three-dimensional (3D) images. METHODS: In this study, cone-beam computed tomography (CBCT) images from 15 patients with maxillary constriction (mean age 12 ± 1.6 years) were included. RME treatment with Hyrax appliance was performed in all patients. CBCT scans were taken at three different times; before appliance insertion (T0), after active expansion (T1) and 3 months after appliance insertion (T2). We developed a novel Matlab-based application to quantify NSD based on the tortuosity ratio by dividing the actual length of the septum by the ideal length in the mid-sagittal plane by using this application. RESULTS: Tortuosity ratio (TR) values were found as 1.03 ± 0.03 (T0), 1.02 ± 0.02 (T1), and 1.02 ± 0.02 (T2). Differences of TR values among these groups were evaluated using the statistical method of ANOVA (ANalysis Of VAriance) for repeated measures with the significance level of p ≤ .05. Results showed significant reductions in TR values between T0-T1 (p ≤ .05) and between T0-T2 (p ≤ .05). Nonetheless, a significant difference between T1-T2 was not determined (p > .05). CONCLUSIONS: As a result, we can conclude that the NSD degree is affected by the RME treatment. The developed application can be used for both educational and research purposes.

Cone-beam computed tomographic evaluation of accessory mental foramen in a Turkish population.

PURPOSE: The aim of this study was to evaluate the frequency and location of accessory mental foramen (AMF) in a Turkish population using cone beam computerized tomography (CBCT). METHOD: CBCT images of 1005 patients were retrospectively reviewed from the archive of the Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Izmir Katip Celebi University. The prevalence, size, and localization of AMFs were assessed according to gender and age. In addition, the vertical and horizontal dimension of the mental foramen (MF) with and without AMF was measured to investigate the relationship between MF dimensions and the presence and absence of AMF. The average distance between the MF and AMF was also calculated. All measurements were then analyzed statistically. RESULTS: A total of 149 AMFs in 123 (12.23%) patients were identified on the CBCT images of the 1005 patients reviewed. There was no significant correlation between presence of AMF and gender (p = 0.152). The most common localization of an AMF with respect to the MF was posterio-inferior (n = 52; 34.89%). A statistically significant difference was also found between the vertical and horizontal dimensions of the MF with and without AMF (p < 0.05). CONCLUSION: The results of this study demonstrate the high prevalence of AMF in the studied Turkish population. Considering the high prevalence and the structures passing through it, recognition of AMF and its detection using CBCT is important to prevent complications that may occur during and after surgical procedures.

Effects of toothpastes on white spot lesions around orthodontic brackets using quantitative light-induced fluorescence (QLF) : An in vitro study.

AIM: The aim of this study was to investigate the effects of toothpastes with different contents on the remineralization of white spot lesions around orthodontic brackets by quantitative light-induced fluorescence (QLF). MATERIALS AND METHODS: A total of 45 freshly extracted human mandibular first molars were selected. Artificial caries lesions were created on enamel surfaces using an acidified gel system for 7 days. Initial relative fluorescence loss was calculated as the pretreatment (baseline) fluorescence value by QLF device. Molar tubes were bonded using light-cured resin composite cement. The specimens were randomly divided into three experimental groups (n = 15). Different toothpastes were applied to demineralized enamel: (1) fluoride-containing toothpaste (Colgate Total®), (2) Novamin-containing toothpaste (Sensodyne® Repair and Protect), (3) probiotic-containing toothpaste (GD Probiotic Toothpaste®). After 2 weeks of treatment, fluorescence loss and lesion area were measured with QLF. To determine fluorescence changes, intergroup comparisons were performed with a multivariate analysis of variance, followed by Tukey's test at a probability value of p < 0.05. RESULTS: Significant differences were observed between initial and posttreatment QLF measurements of the demineralized enamel specimens treated with the various agents (p < 0.05). In all experimental groups, significant fluorescence radiance increase and decrease of the lesion area (p = 0.000) was found. CONCLUSION: Novamin-containing toothpaste provided more increase of fluorescence compared to fluoride- and probiotic-containing toothpastes.

Comparison of dental arch and mandibular-maxillary base widths between true and pseudo-Class III malocclusions.

INTRODUCTION: The aim of the study was to analyze the morphology of dental arches and skeletal mandibular-maxillary bases in untreated pseudo-Class III and true Class III malocclusions, by using posteroanterior radiographs and 3-dimensional digital models. METHODS: The records of 50 untreated patients (24 boys and 26 girls between 14 and 16 years of age) with Class III malocclusions were included in this study. They were divided into 2 groups according to their Class III malocclusion type: true or pseudo-Class III malocclusion. Maxillary skeletal base, and bigonial and biantegonial widths were measured on posteroanterior cephalograms. Also, maxillary and mandibular intermolar widths were calculated on 3-dimensional digital models. For the statistical evaluation, the independent-samples t test was used, and the Pearson correlation coefficient was calculated to determine the relationship between the dental and skeletal widths. RESULTS: Maxillary intermolar, and bigonial and biantegonial widths in true Class III malocclusions were significantly larger than those in pseudo-Class III malocclusions (P <0.05). On the other hand, maxillary skeletal base width in pseudo-Class III malocclusions was significantly larger than in true Class III malocclusions (P <0.05). Also, mandibular intermolar widths in true Class III malocclusions were larger than in pseudo-Class III malocclusions, but the difference was not significant (P >0.05). Significant positive correlations were determined not only between the maxillary and mandibular molar widths but also between the bigonial and biantegonial widths (P <0.01). CONCLUSIONS: The morphologies of the dental arches and the skeletal mandibular-maxillary bases differ in a significant manner between untreated pseudo-Class III and true Class III malocclusions.

Different pulse modes of Er:YAG laser irradiation: effects on bond strength achieved with self-etching primers.

OBJECTIVE: The aim of this study was to compare the effects of different pulse modes of Er:YAG laser on shear bond strength (SBS) of orthodontic brackets bonded with self-etching primers (SEP) and phosphoric acid etching. MATERIALS AND METHODS: A total of 120 human mandibular third molars were randomly assigned to 3 groups of 40 specimens depending on the bonding procedure to be used. The groups were divided into two subgroups according to the pulse mode of the erbium-doped yttrium aluminum garnet (Er:YAG) laser irradiation as medium-short pulse (MSP) mode and quantum-square pulse (QSP) mode at 120 mJ, 10 Hz, 1.2 W. In each subgroup, the mesio- or distobuccal tooth surfaces were randomly assigned as experimental or control sides. After surface preparation with different modes of Er:YAG laser on experimental side, whole buccal tooth surfaces were treated with phosphoric acid etching or two different SEPs. Then metallic brackets were bonded with Transbond XT (3 M Unitek, Monrovia, CA, USA) or Kurasper F (Kuraray, Okayama, Japan). SBS values and the amount of adhesive remaining on the tooth after debonding were assessed. One-way analysis of variance (ANOVA) was used to evaluate the changes in mean SBS between groups resulting from laser etching, followed by post hoc test of Tukey. RESULTS: There were statistically significant differences between the experimental and control sides of all groups (p < 0.05). CONCLUSION: Laser etching with QSP and MSP modes increases the SBS of metallic brackets and Er:YAG laser irradiation with QSP mode increases the SBS of SEPs.

Effects of different pre-treatment methods on the shear bond strength of orthodontic brackets to demineralized enamel.

OBJECTIVE: To compare the effects of different treatment methods used for the enamel damage, on the shear bond strength (SBS) and fracture mode of orthodontic brackets. MATERIALS AND METHODS: Freshly-extracted 140 premolars were randomly allocated to seven groups: Group I was considered as the control of other groups. The remaining groups were exposed to demineralization. In group II, brackets were directly bonded to the demineralized enamel surface. CPP-ACP paste (GC Tooth Mousse), fluoride varnish (Bifluorid 12), microabrasion with a mixture prepared with 18% hydrochloric acid and fine pumice powder, microabrasion with an agent (Opalustre) and resin infiltrant (Icon®) were applied in Groups III, IV, V, VI and VII, respectively. The specimens were tested for SBS and bond failures were scored according to the Adhesive Remnant Index (ARI). Analysis of variance and Tukey tests were used to compare the SBS of the groups. ARI scores were compared with G-test. The statistical significance was set at p < 0.05 level. RESULTS: Statistically significant differences were found among seven groups (F = 191.697; p < 0.001). The SBSs of groups I (mean = 18.8 ± 2.0 MPa) and VII (mean = 19.1 ± 1.4 MPa) were significantly higher than the other groups. No statistically significant difference was found between groups IV (mean = 11.5 ± 1.2 MPa) and V (mean = 12.6 ± 1.5 MPa). The differences in ARI scores of the groups were statistically significant (p < 0.01). CONCLUSIONS: All demineralization treatment methods improve bonding to demineralized enamel. Resin infiltrant application after demineralization showed similar bond strength values as intact enamel.

Curve of Spee and its relationship to vertical eruption of teeth among different malocclusion groups.

INTRODUCTION: Our objectives were to assess the depth of the curve of Spee (COS) in different malocclusion groups, to relate this to the eruption of anterior or posterior teeth quantitatively, and to determine whether the depth of the COS is affected by the vertical eruption of anterior or posterior teeth. METHODS: Two hundred conventional lateral cephalograms and 3-dimensional models of untreated patients (70 boys, mean age: 16.4 ± 1.4 years; 130 young women, mean age: 18.1 ± 1.8 years) were included and assigned to 4 malocclusion groups as Class I, Class II Division 1, Class II Division 2, and Class III. The depth of the COS, overjet, and overbite were measured on 3-dimensional models. The perpendicular distance between the incisal tip of the mandibular central incisor (L1-MP), the deepest point of the COS (S-MP), and the distobuccal cusp tip of the mandibular second molar (L7-MP) to the mandibular plane were calculated and proportioned with each other. The Pearson correlation coefficient was calculated, and multiple linear regression analysis was carried out. Also, multivariate analysis of variance was performed at the P <0.05 level. RESULTS: The mesiobuccal cusp of the first molar was the deepest part of the COS in all groups, with a maximum depth of 2.44 ± 0.73 mm in the Class II Division 1 subjects and a minimum depth of 1.76 ± 0.94 in the Class III subjects. The depth of the COS changed as follows: Class II Division 1 > Class II Division 2 > Class I > Class III malocclusion groups. Statistically significant positive correlations were found between the depth of the COS and L1-MP/S-MP (r = 0.541) and L7-MP/S-MP (r = 0.269) in the Class I and Class III subjects, and between the depth of the COS and overjet (r = 0.483) and L7-MP/S-MP (r = 0.289) in the Class II Division 1 subjects. All variables except overjet had positive correlations with the depth of the COS in Class II Division 2 subjects. The multivariate analysis of variance showed statistically significant differences in overjet, overbite, L1-MP/S-MP, L7-MP/S-MP, and the depth of the COS (P <0.001) among the groups. CONCLUSIONS: Although the overjet differed, vertical eruption of the anterior teeth did not differ among the different malocclusion groups and had a significant contribution to the depth of the COS in subjects with Class I and Class III malocclusions.

Development of the curve of Spee in Class II subdivision malocclusion: a longitudinal study.

OBJECTIVE: To compare the depth of curve of Spee (COS) in Class I and II sides of Class II subdivision malocclusion longitudinally and to describe the changes in the COS in relation to dental arch over time. MATERIALS AND METHOD: The study group comprised 17 subjects exhibiting Class II subdivision malocclusion. The depth of COS, intermolar width, distances from mesial anatomic contact points of the first permanent molars to the contact point of the central incisors in Class I and II sides and arch length in mandible were analysed on digital models in three different time points based on cervical vertebral maturation (T1; mean age: 12.4 years, T2; mean age: 15.1 years, and T3: mean age: 19.1 years). Pearson's correlation coefficients were calculated and linear multiple regression analysis with enter method was carried out. RESULTS: No significant differences were found in the depth of COS between Class I and II sides in all time periods. The mesiobuccal cusp of the first molar was the deepest part of COS in both sides and in all time periods, with a maximum depth of 2.37±0.83mm in T1 and a minimum depth of 1.91±0.66mm in T3. Between baseline and final follow-up; the depth of COS, ach length, and distance in Class I side decreased significantly. Arch length had a significant correlation with the depth of COS (r = 0.471) in T3. CONCLUSIONS: As the depth of COS did not differ between either the Class II or I sides, the same mechanics can be used to level the COS in either sides of the mandibular arch.

Buccal cortical bone thickness at miniscrew placement sites in patients with different vertical skeletal patterns.

OBJECTIVE: Cortical bone thickness plays an important role in the primary stability of miniscrews. The purpose of this study was to evaluate the buccal cortical bone thickness in adolescent subjects with different vertical skeletal patterns using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: We examined the CBCT images of 75 patients (30 males, 45 females; mean age 16.5 years; range 15.3-17.7 years) in the present study. High-, average- and low-angle subgroups were generated according to SN-GoMe angle. On volumetric images, we measured the buccal cortical bone thickness from canine to the second molar teeth at heights of 5, 7 and 9 mm from cemento-enamel junction (CEJ). For statistical evaluation, the Wilcoxon signed rank, Kruskal-Wallis and Tukey HSD tests were applied at the p < 0.05 level. RESULTS: Buccal cortical bone was thickest in the low-angle group. We observed statistically significant differences in the maxilla between the high- and low-angle groups at all levels. In the mandible, we noted statistically significant differences between high-angle and low-angle groups in the canine-first premolar regions at heights of 5 and 7 mm, and in the second premolar-first molar region at 7 mm height from CEJ. Significant differences were also present between the first and second premolars at heights of 7 and 9 mm. Average cortical bone thickness ranged from 1.10-1.37 mm in the maxilla and 1.20-3.28 mm in the mandible for all groups. CONCLUSION: Buccal cortical bone thickness in adolescents varied in different vertical skeletal patterns and was greater in the mandible than in the maxilla, with the distance increasing from the CEJ to the apex. As the buccal cortical bone is thinner in high-angle patients, patient-specific measures should be taken when performing miniscrew treatment.

Longitudinal evaluation of dental arch asymmetry in Class II subdivision malocclusion with 3-dimensional digital models.

INTRODUCTION: Class II subdivision malocclusions with their asymmetric occlusal relationships often pose treatment difficulties. The aim of this study was to evaluate the longitudinal changes of dental arch asymmetry in untreated subjects with Class II subdivision malocclusion. METHODS: From 706 files from the University of Michigan Growth Study, longitudinal records of 17 untreated subjects with Class II subdivision malocclusion were included this study. Dental arch changes at 3 consecutive longitudinal intervals, defined by the cervical vertebral maturation method, were analyzed on digital dental models. The average ages of the subjects were 12.4, 15.1, and 19.1 years at the 3 time periods, respectively. Maxillary and mandibular reference lines were constructed and used for the intra-arch asymmetry measurements. The Friedman test and analysis of variance with repeated measures were used to determine dental arch asymmetries at the P <0.05 level. RESULTS: All subjects were found to have a type 1 Class II subdivision malocclusion characterized by distal positioning of the mandibular first molar on the Class II side. No statistically significant intra-arch asymmetry changes were found for the maxillary and mandibular dental arches in any time period. Between the baseline and the final follow-up, the data indicated decreases in maxillary and mandibular intercanine arch widths and arch lengths symmetrically. CONCLUSIONS: The results of this study indicate that the dental arch asymmetry in patients with Class II subdivision malocclusions did not improve or worsen with growth.

OPG and RANKL levels around miniscrew implants during orthodontic tooth movement.

INTRODUCTION: The aim of this study was to determine the peri-miniscrew implant crevicular fluid receptor activator of nuclear factor-кB ligand (RANKL) and osteoprotegerin (OPG) levels around loaded and unloaded miniscrew implants at different time intervals. METHODS: Twenty loaded and 16 unloaded miniscrew implants were included in this study. All miniscrew implants were placed bilaterally between the maxillary second premolars and first molars as anchorage units for canine distalization. Peri-miniscrew implant crevicular fluid was taken from the mesiobuccal aspects of the loaded and unloaded miniscrew implants before loading; at 24, 48, and 168 hours; and on day 30 after force application. Enzyme-linked immunosorbent assay kits were used to determine RANKL and OPG levels in the peri-miniscrew implant crevicular fluid samples. Wilcoxon, Mann-Whitney U, and Spearman correlation tests were used for statistical evaluations at the P <0.05 level. RESULTS: Although the total amount of OPG was not different between the groups, the total amount of RANKL was significantly elevated in the loaded miniscrew implant group (P <0.05) at all time periods. Peri-miniscrew implant crevicular fluid volume was the highest at 48 hours in the loaded group. Also, the OPG/RANKL ratio in the peri-miniscrew implant crevicular fluid was significantly decreased in the loaded miniscrew implant group. CONCLUSIONS: The OPG and RANKL levels vary around loaded and unloaded miniscrew implants as a result of force application.

Evaluation of alveolar bone loss following rapid maxillary expansion using cone-beam computed tomography.

OBJECTIVE: To evaluate the changes in cortical bone thickness, alveolar bone height, and the incidence of dehiscence and fenestration in the surrounding alveolar bone of posterior teeth after rapid maxillary expansion (RME) treatment using cone-beam computed tomography (CBCT). METHODS: The CBCT records of 20 subjects (9 boys, mean age: 13.97 ± 1.17 years; 11 girls, mean age: 13.53 ± 2.12 year) that underwent RME were selected from the archives. CBCT scans had been taken before (T1) and after (T2) the RME. Moreover, 10 of the subjects had 6-month retention (T3) records. We used the CBCT data to evaluate the buccal and palatal aspects of the canines, first and second premolars, and the first molars at 3 vertical levels. The cortical bone thickness and alveolar bone height at T1 and T2 were evaluated with the paired-samples t-test or the Wilcoxon signed-rank test. Repeated measure ANOVA or the Friedman test was used to evaluate the statistical significance at T1, T2, and T3. Statistical significance was set at p < 0.05. RESULTS: The buccal cortical bone thickness decreased gradually from baseline to the end of the retention period. After expansion, the buccal alveolar bone height was reduced significantly; however, this change was not statistically significant after the 6-month retention period. During the course of the treatment, the incidence of dehiscence and fenestration increased and decreased, respectively. CONCLUSIONS: RME may have detrimental effects on the supporting alveolar bone, since the thickness and height of the buccal alveolar bone decreased during the retention period.

Cone-beam computed tomography evaluation of relationship between tongue volume and lower incisor irregularity.

The aim of this study was to evaluate the relationship between the tongue volume and lower incisor irregularity, using cone-beam computed tomography (CBCT), and to identify the possible gender differences. CBCT images of 60 patients between 16 and 36 years of age were selected from 1400 sets of images in the database. Tomography was carried out using iCAT® (Imaging Sciences International, Hatfield, Pennsylvania, USA) and segmentation was carried out by using Mimics 10.1 software (Materialise NV, Leuven, Belgium). The tongue volume was calculated by using the volume of the voxels from the scan and the number of voxels selected for a given mask. Lower incisor crowding was measured with the Little's irregularity index and divided into three groups: mild, moderate, and severe. Independent samples t-test, analysis of variance (ANOVA), and Tukey test were used at P < 0.05 level. Pearson correlation coefficients and linear regression model were calculated to determine the correlation between tongue volume and incisor irregularity. No significant gender dimorphism was found for the tongue volume (females: 28.13 ± 8.54 cm(3) and males: 31.02 ± 9.75 cm(3)). According to ANOVA, there was statistically significant difference in the tongue volume measurements among subjects with different levels of irregularity. Tukey analysis indicated that mild irregularity group (33.97 cm(3)) showed higher values for tongue volume than severe irregularity group (26.60 cm(3); P = 0.025). The relationship between incisor irregularity and tongue volume was evaluated for both genders and significant inverse correlation (r = -0.429; P = 0.029) was determined between lower incisor irregularity and tongue volume in males. In female group, no significant correlation was determined between tongue volume and incisor irregularity.

Mandibular anterior bony support and incisor crowding: Is there a relationship?

INTRODUCTION: The aim of this study was to test the null hypothesis that increased irregularity of the mandibular incisors is associated with a reduction in the alveolar support on cone-beam computed tomographic sections. METHODS: From a sample of 1100 digital volumetric tomographs, 125 tomographs of subjects with Class I malocclusion (mean age, 21.6 ± 4.8 years) were selected for this study. An irregularity index was used to categorize these tomographs as having mild, moderate, or severe crowding. All tomographs were taken by using an iCAT (Imaging Sciences International, Hatfield, Pa) imaging device. The following parameters were measured on the sections corresponding to the 4 mandibular incisors with the iCAT software: height, thickness, and area of the entire symphysis; height, thickness, and area of the cancellous bone of the symphysis; and distance between the vestibular and lingual cortices. For the statistical evaluation, independent samples t test, analysis of variance, and the Tukey HSD test were used at an alpha level 0.05. The Pearson correlation coefficient and a simple linear regression were calculated to determine the relationship between mandibular anterior bony support and incisor crowding. RESULTS: Almost all mandibular anterior bone measurements were greater in the male subjects than in the female subjects (height of the mandibular symphysis, P <0.001; cancellous bone height, P <0.001). Female subjects with mild crowding had higher values for cancellous bone height (P = 0.025) and vestibular cancellous bone thickness (P = 0.004) than did those with severe crowding. However, no differences were detected in the male subjects. Additionally, significant correlations were determined between incisor crowding and thickness of the mandibular symphysis, cancellous bone thickness, and the vestibular part of cancellous bone thickness in female subjects. CONCLUSIONS: Significant relationships were found between the measures of mandibular incisor crowding and basal bone dimensions in female subjects. Except for the vestibular part of cancellous bone thickness, all mandibular incisor bone measurements were greater in the male subjects than in the female subjects.