Three-dimensional decision support system for treatment of canine impaction.

INTRODUCTION: This study aimed to develop a 3-dimensional (3D) characterization of the severity of maxillary impacted canines and to test the clinical performance of this characterization as a treatment decision support tool. METHODS: Cone-beam computed tomography images obtained from 83 patients with 120 impacted maxillary canines were included. Quantitative information on the canine 3D position and qualitative assessment of root damage of adjacent teeth were evaluated. A severity index was constructed on the basis of the quantitative findings. Clinical applicability was tested by comparing clinical diagnosis and treatment planning for conventional records vs the 3D characterization via a 2-part survey. RESULTS: The average quantitative assessments of impacted maxillary canine position were 6.4 ± 3.6 mm from the midsagittal plane, 11.6 ± 3.1 mm in height relative to the occlusal plane, 31.5° ± 18° of roll, and 48.8° ± 14.3° of pitch. The severity index ranged from 0-13 with a mean score of 4.5 ± 2.2. Overlap with adjacent teeth was the greatest contributor (33%) to the index. Bicortically impacted canines caused the most severe root damage. Cone-beam computed tomography was preferred for assessing root damage and overall severity, whereas conventional imaging was sufficient for height and angulation assessment. The 3D report was very important or important for evaluating root damage, canine position, overall severity, and overlap. The 3D report changed most of the decisions relating to biomechanics, patient education, and treatment time estimate. The decision of exposure and traction vs extraction was changed 22% of the time after the presentation of the 3D report. CONCLUSIONS: The overlap with adjacent teeth frequently contributes the most to the severity index. The 3D report provided relevant clinical information regarding the canine position, damage to adjacent teeth, and the severity index, with a profound impact on the decisions of the clinicians regarding biomechanics, patient education, and treatment time estimate.

Sagittal Position of the Upper Incisor in Relation to the Forehead in Peruvian Individuals with Different Skeletal Relationships.

AIM: The aim of this study was to determine the sagittal position of the upper incisor considering Andrews' analysis based on the position of the forehead in Peruvian individuals with different skeletal relationships. MATERIALS AND METHODS: This retrospective, cross-sectional study included 212 lateral head radiographs of Peruvian individuals (males: 85, mean age 21.38 ± 6.88, and females: 127, mean age 21.18 ± 6.95), with different skeletal relationships (Class I group = 96, Class II group = 57, Class III group = 59). The values of the ANB, SNA, SNB angles as well as the forehead anterior limit line (FALL) and goal anterior limit line (GALL) points were identified in the radiographs, and then a vertical line was drawn in each point to determine if the upper incisor was positioned forward (protruded), backward (retruded) or within (adequate) these lines. Two trained and calibrated investigators performed all the measurements. The Chi-square test was used to evaluate associations. A p-value < 0.05 was considered statistically significant. RESULTS: Overall, the sagittal position of the upper incisor showed a significant association with the sagittal skeletal relationship (p = 0.001). The upper incisors showed an adequate position (41.7%), protruded position (56.10%), and retruded position (42.40%), for Class I, II, and III skeletal relationships, respectively, as highest percentages in each Class. Statistical significance was found for females only (p = 0.005). CONCLUSION: Skeletal Class I mainly showed an adequate position of the upper central incisor, whereas for Class II a protruded position was most frequently found, and Class III presented a retruded position. CLINICAL SIGNIFICANCE: Andrews' analysis based on the position of the forehead in Peruvian individuals is a valuable tool for orthodontic diagnosis. How to cite this article: Bazán-Mendoza JR, Arias-Modesto PB, Ruíz-Mora GA, et al. Sagittal Position of the Upper Incisor in Relation to the Forehead in Peruvian Individuals with Different Skeletal Relationships. J Contemp Dent Pract 2023;24(11):821-825.

Comparison and reproducibility of three methods for maxillary digital dental model registration in open bite patients.

OBJECTIVE: To compare and assess the reproducibility of 3 methods for registration of maxillary digital dental models in patients with anterior open bite. Settings and sample population Digital dental models of 16 children with an anterior open bite in the mixed dentition were obtained before (T1) and after 12 months of treatment with bonded spurs (T2). METHODS: Landmarks were placed on all T2 models and 3 registration methods (R1, R2 and R3) were independently performed by 2 observers. R1 was based on 10 landmarks placed on posterior teeth. R2 was based on 5 landmarks on the palate (2 anterior, 2 posterior and 1 central). R3 used regions of interest around the 5 palatal landmarks used in R2. The differences between the registration methods were calculated by comparing the mean differences and standard deviations between the corresponding x, y and z coordinates of 6 corresponding landmarks in the T2 registered models. Repeated measures analysis of variance followed by post-hoc Bonferroni tests were used for comparisons (P < .05). The agreement between methods and the intra and interobserver reproducibility were assessed with Bland-Altman tests and intraclass correlation coefficients (ICC). RESULTS: Comparisons of R2 with R3 methods showed greater agreement, mean differences ≤0.50 mm for all landmarks, than comparisons of R1 with R2, and R1 with R3, mean differences >0.50 mm for most of the y and z coordinates (P < .05). The R1 and R3 methods presented excellent intra and interobserver reproducibility and R2 method had moderate interobserver reproducibility. CONCLUSIONS: Longitudinal assessments of open bite treatment using digital dental models could consider the posterior teeth and/or the palate as references. The R1 and R3 methods showed adequate reproducibility and yield different quantitative results. The choice will depend on the posterior teeth changes and dental models' characteristics.

Virtual learning object for developing knowledge about the diagnosis and management of molar incisor hypomineralization.

AIM: To develop, apply, and evaluate a virtual learning object (VLO) for teaching undergraduate dental students and paediatric dentists to diagnose and manage molar incisor hypomineralization (MIH). DESIGN: This controlled educational intervention included 170 undergraduate dental students and 50 paediatric dentists. The student intervention group (VLOG) was trained by the VLO, the control group of students (CG) received a synchronous virtual class, and the group of paediatric dentists (PDG) was trained by the VLO. Pre-test and post-test data were analyzed with a mixed one-way and Tukey's post hoc ANOVA test (α = 0.05). The answers to the questionnaire were analyzed with the one-way ANOVA test and Tukey's post hoc test (α = 0.05). RESULTS: The values obtained in the pre-test were significantly lower than those obtained in the post-test for all groups. The specialists showed a higher level of knowledge before and after the MIH training compared with the students (p < .001). Similarly, statistical differences were found in the level of knowledge, which increased after MIH training (p < .001). There were no differences between the CG and VLOG. CONCLUSIONS: The level of knowledge increased in all groups after training regardless of the method used. VLOG works similar to traditional teaching approaches.

Association Between Breastfeeding Type and Duration and the Molar and Facial Characteristics of Preschoolers Aged 2 To 6 Years: A Cross-Sectional Study.

OBJECTIVE: To calculate the association between the type and duration of breastfeeding and the deciduous molar relationship and facial characteristics of preschoolers aged 2 to 6 years. STUDY DESIGN: This crosssectional study included 160 pre-schoolers aged 2 to 6 years old, enrolled in the 2019 academic year from 3 public schools in Data collection involved two phases. The first phase consisted in determining the facial type, anteroposterior and vertical profile, facial dimensions, and the molar relationship between primary second molars. The second phase included interviews with the parents or legal guardians. Children with exclusive breastfeeding and with mixed/artificial feeding (breastfeeding and bottle-feeding, or exclusive artificial bottle-feeding) were included. Chi-square test, t-test, multiple linear regression, and binary logistic regression tests were applied (p<0.05). RESULTS: The facial length, width, and the lower third were greater in the exclusive breastfeeding group than in the mixed/artificial feeding group (3.74mm, p=0.002; 2.06mm, p=0.047; and 2.94mm, p=0.015; respectively). In addition, children with breastfeeding for more than six months showed greater facial length, facial width and lower third (3.20mm, p=0.038; 3.68mm, p=0.006; and 3.57mm, p=0.026; respectively). The duration of exclusive breastfeeding influenced facial width, noting an increase of 3.32mm (p=0.011) if a pre-schooler had exclusive breastfeeding for more than six months. CONCLUSION: There were no significant associations between type and duration of breastfeeding and the molar terminal plane, facial type, or profile. However, facial dimensions were greater in the exclusive breastfeeding group, and when breastfeeding was longer than six months.

Dentoskeletal changes in open bite treatment using spurs and posterior build-ups: A randomized clinical trial.

INTRODUCTION: This single-center 2-arm parallel randomized clinical trial aimed to compare the dentoskeletal effects of bonded spurs combined with posterior build-ups vs conventional bonded spurs in the treatment of anterior open bite malocclusion in the mixed dentition. METHODS: Patients aged from 7 to 11 years with anterior open bite, recruited at a university orthodontic clinic, were randomly allocated into 2 groups. The experimental group consisted of patients treated with bonded spurs combined with posterior build-ups. The comparison group comprised patients treated with conventional bonded spurs. Lateral headfilms were obtained at pretreatment and after 12 months of treatment. The primary outcome was the change in the overbite. Randomization was performed using the Web site www.randomization.com. Sequentially numbered opaque and sealed envelopes were used for allocation concealment. Blinding was applicable for outcome assessment only. Intergroup comparisons were performed using t or Mann-Whitney U tests (P <0.05). Mean difference (MD) and 95% confidence interval (CI) were obtained. RESULTS: The experimental group included 24 patients (17 female, 7 male; mean age, 8.22 ± 1.06 years) and the comparison group comprised 25 patients (14 female, 11 male; mean age, 8.30 ± 0.99 years). Baseline demographic and cephalometric characteristics were similar between groups. After 12 months, all patients showed improvements. Both groups showed similar improvements of the overbite (MD, 0.00 mm; 95% CI, -0.92 to 0.91), similar slight decreases of the gonial (MD, 0.02°; 95% CI, -1.11 to 1.15) and mandibular plane (MD, 0.15°; 95% CI, -0.64 to 0.93) angles, and similar mandibular molar extrusion (MD, 0.14 mm; 95% CI, -0.27 to 0.56). The experimental group showed significantly smaller extrusion of the maxillary first molar than the comparison group (MD, -0.70 mm; 95% CI, -0.92 to -0.49). The other dentoskeletal variables showed similar changes without statistically significant intergroup differences. No serious harm was observed other than plaque accumulation around the spurs. CONCLUSIONS: Similar overbite increases and dentoskeletal changes were observed in both groups after 12 months of treatment. Although the experimental group showed significantly smaller extrusion of the maxillary molars, no greater counterclockwise rotation of the mandible than the comparison group was observed. REGISTRATION: This trial was registered at Clinicaltrials.gov (Identifier NCT03702881). PROTOCOL: The protocol was not published. FUNDING: This trial was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES), Finance Code 001; and by grants: no. 2017/06440-3, no. 2018/05238-9 and no. 2018/24003-2, São Paulo Research Foundation (FAPESP).

Influence of upper lip curvature on smile attractiveness in patients with different degrees of gingival smiles: A cross-sectional study with opinions from oral health providers and laypersons.

INTRODUCTION: Although there is relative consensus about approaches to gingival smile management, there are still discrepancies as to whether a gingival smile is attractive or not. The purpose of this study was to quantify the influence of upper lip curvature shape and the amount of gingival display on the perception of smile attractiveness assessed by Peruvian orthodontists, dentists, and laypersons. METHODS: A frontal photograph was digitally altered to generate 3 types of upper lip curvature shapes (upward, straight, and downward) with 5 different levels of gingival smile exposure (0 mm, 2 mm, 3 mm, 4 mm, and 5 mm). Fifteen images were generated. Three groups of evaluators (50 dentists, 50 orthodontists, and 50 laypersons) assessed the images using a visual analog scale. One-way analysis of variance with Bonferroni post-hoc tests and multiple linear regressions were applied. RESULTS: The downward lip curvature shape had a negative effect on the esthetic evaluation of the smile with gingival exposures of 3 mm or more for all the evaluating groups (approximately 20-30 points less than upward or straight smile curvature shapes, P <0.05). Laypeople gave higher scores of almost 10 points more than dentists and orthodontists when evaluating the upward lip curvature shape with 5 mm of gingival exposure during smile (P = 0.029). CONCLUSIONS: We found that upward or straight upper lip curvature shapes have a positive impact on perceived smile esthetics. In contrast, downward upper lip curvature shapes have a negative effect on perception when evaluating different degrees of gingival smiles.

Dental arch changes after open bite treatment with spurs associated with posterior build-ups in the mixed dentition: A randomized clinical trial.

INTRODUCTION: This single-center, 2-arm, parallel-group randomized clinical trial aimed to compare the dimensional dental arch changes after anterior open bite (AOB) treatment with bonded spurs associated with posterior build-ups vs bonded spurs alone. METHODS: Patients aged between 7 and 11 years with AOB were recruited at a university clinic and randomly allocated into 2 groups. The experimental group was treated with bonded spurs associated with posterior build-ups (SBU) and the comparison group with bonded spurs alone (S). Digital dental models were obtained at pretreatment and after 12 months of treatment. The overbite change was the primary outcome. The randomization list was obtained at the Web site www.randomization.com. Allocation concealment involved sequentially numbered, sealed, and opaque envelopes. The outcomes' assessment was blinded. Analysis of covariance was used for intergroup comparisons (P <0.05). Mean difference (MD) and 95% confidence interval (CI) were obtained. RESULTS: Twenty-four patients (mean age, 8.22 ± 1.06 years; 7 males and 17 females) were included in the SBU group, and 25 patients (mean age, 8.30 ± 0.99 years; 11 males and 14 females) were included in the comparison group. After a 12-month follow-up, the overbite increased approximately 4 mm in both groups (MD, -0.11 mm; 95% CI, -1.03 to 0.80). Means of anterior dentoalveolar vertical development ranged from 2.24 mm (S group) to 2.49 mm (SBU group) and from 1.31 mm (SBU group) to 1.55 mm (S group) for the maxilla (MD, -0.24 mm; 95% CI, -0.91 to 0.44) and mandible (MD, 0.29 mm; 95% CI, -0.39 to 0.96), respectively. The maxillary intermolar distance decreased in the SBU group and increased in the S group (MD, -0.48 mm; 95% CI, -0.92 to -0.03). The mandibular intermolar distance increased in the SBU group and decreased in the comparison group (MD, 0.26 mm; 95% CI, 0.004-0.52). Plaque accumulation around the spurs was observed in some patients. CONCLUSIONS: Both protocols demonstrated similar improvements in the AOB with similar effects on the dental arches. The SBU group showed a slight decrease in the maxillary intermolar distance and a slight increase in the mandibular intermolar distance, whereas opposite changes were observed for the S group. REGISTRATION: This trial was registered at Clinicaltrials.gov (Identifier NCT03702881). PROTOCOL: The study protocol was not published. FUNDING: This work was supported by the São Paulo Research Foundation (FAPESP) grants nos. 2017/06440-3, 2018/05238-9, and 2018/24003-2; and financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-Brasil (CAPES), Finance Code 001.

Class II malocclusion treatment with a customized dual force distalizer.

Intraoral distalizers associated with skeletal anchorage provide the major benefit of promoting molar distalization with minimum anchorage loss and patient cooperation. This case report presents the treatment of a 17-year-old female with Class II Division 2 malocclusion, maxillary dentoalveolar protrusion, mild mandibular retrusion, increased overjet, deepbite, and lip incompetence. The treatment plan involved initial maxillary molar distalization with a customized version of the skeletally anchored dual force distalizer (DFD). The customized DFD used smaller mini-implants and included a fixed anterior biteplane. The device applied simultaneous forces from the buccal and palatal sides directly to the molars using nickel-titanium coil springs and allowed orthodontic mechanics in the mandibular teeth. An overcorrected Class I molar relationship was obtained after 6 months. After the distalization phase, retraction mechanics began with retraction loops and using a modified transpalatal bar reinforced with the mini-implants as anchorage. Moreover, the finishing phase was performed with multiloop edgewise archwires and intermaxillary elastics to enable an individualized control of each tooth. Total treatment time comprised 2 years 4 months, and significant improvements regarding the facial and occlusal perspectives were noticed. Similarly, these favorable changes remained stable during the 2-year follow-up period. The customized version of the skeletally anchored DFD followed by fixed appliances showed effectiveness and stability in Class II malocclusion treatment.

Changes in alveolar bone morphology after traction of buccally vs palatally unilateral maxillary impacted canines: A cone-beam computed tomography study.

INTRODUCTION: The objective of this study was to evaluate the 3-dimensional changes in alveolar bone morphology after traction of buccally vs palatally unilateral maxillary impacted canines (MIC). METHODS: Following a split-mouth model, 27 cone-beam computed tomography images of unilaterally MIC (14 palatally and 13 buccally) and 27 contralateral unimpacted controls were obtained before and after traction using nickel-titanium closed-coil springs and a rigid anchorage appliance. Alveolar bone height and width were measured in the axial, coronal, and sagittal slides by 3 calibrated orthodontists, taking into account the impaction characteristics. A t test was used to compare the 2 groups, and a paired t test was applied for intragroup comparisons (both sides). A multiple linear regression model was used to evaluate the influence of the predictor variables on alveolar bone dimensional changes. RESULTS: The alveolar height showed a significantly greater decrease in palatally MIC (2.09 to 2.79 mm) than buccally MIC (0.28 to 0.57 mm) (P <0.05) for all surfaces. However, the alveolar width increased similarly in both groups up to 1.36 mm. In general, the affected side had a more significant height loss and greater increases in alveolar width than the nonaffected side. Regression analysis indicated that buccally MIC and age decreased alveolar changes, whereas female sex increased alveolar changes (P <0.05). CONCLUSIONS: MIC traction with nickel-titanium closed-coil springs and heavy anchorage induces significant 3-dimensional changes in alveolar bone characterized by alveolar bone height decreases and cervical alveolar bone width increases. The height decrease is greater in palatally than in buccally MIC.

Bucco alveolar bone thickness of mandibular impacted third molars with different inclinations: a CBCT study.

PURPOSE: To compare the buccal alveolar bone thickness of mesioangulated mandibular impacted third molars (MITM) with buccal versus lingual inclination using cone-beam computed tomography (CBCT). METHODS: This retrospective cross-sectional study evaluated 69 individuals (39 women and 30 men) who presented a total of 101 mesioangulated MITM according to the Winter classification and in B position according to the Pell and Gregory classification. The average age was 22.99 ± 3.94 years. The superior, medial and inferior alveolar thickness regarding buccal (n = 44) or lingual (n = 57) mandibular third molar inclination were measured. T test or Mann-Whitney U test and finally, a multiple linear regression were applied (p < 0.05). RESULTS: The buccal alveolar bone thickness of mesioangulated mandibular impacted third molars was significantly greater in the group with lingual inclination compared to the group with buccal inclination, in the superior region (6.21 ± 3.27 vs. 4.85 ± 3.06; p = 0.036). The lingual inclination significantly influenced the buccal alveolar bone thickness in the middle region (p = 0.011). CONCLUSIONS: The mesioangulated MITM in B position with lingual inclination have a greater thickness of the superior and medial buccal alveolar bone than the MITM with buccal inclination. These results should be considered during MITM diagnosis and surgical planning.

Influence of maxillary canine impaction characteristics and factors associated with orthodontic treatment on the duration of active orthodontic traction.

INTRODUCTION: Orthodontic traction of a maxillary impacted canine (MIC) increases the orthodontic treatment time. Therefore, the objective of this study was to evaluate the influence of MIC characteristics and factors associated with orthodontic treatment on the duration of active orthodontic traction. METHODS: This follow-up and retrospective study included 45 MICs orthodontically tractioned into the occlusal plane with the use of a standardized protocol. MIC characteristics, including type, sector, side, location, height, and complexity of impaction, as well as α and ß angles and canine root length and area were measured. Likewise, factors associated with orthodontic treatment, including sex, age, malocclusion, premolar extractions, previous incisor root resorption, ANB, APDI, and SNA angles, and PNS-ANS distance were also evaluated. The statistical analysis included multiple linear regressions to estimate the influence of all variables on the duration of traction (α = 0.05). RESULTS: Sex had significant influence (P = 0.027) on the time of traction; in female patients, the time was 2.05 months more than in male patients. Bilateral impaction treatment increased the time by 2.74 months compared with unilateral cases (P = 0.001). Traction of bicortically centered impacted canines increased the duration of traction by 2.85 months (P = 0.001). Finally, the traction time increased in 2.35 months (P = 0.046) when the impaction sectors were 4 or 5 (close to the midline). CONCLUSIONS: The duration of active orthodontic traction of MIC is mainly influenced by sex, bilateral type, bicortically centered location, or when MIC is located in sector 4 or 5 close to midline, increasing the traction time by some months.

Changes in maxillary incisor inclination and position after traction of unilateral vs bilateral maxillary impacted canines in nonextraction treatment: A cone-beam computed tomography study.

INTRODUCTION: The aim of this study was to compare the inclination and position changes of maxillary incisors after traction of unilateral vs bilateral maxillary impacted canines in nonextraction orthodontic treatment. METHODS: This longitudinal and retrospective study evaluated 24 patients with impacted maxillary canines; 12 with unilateral impaction and 12 with bilateral impaction. All subjects had Angle Class I malocclusion and were orthodontically treated with a standardized traction protocol that did not include premolar extractions. Cone-beam computed tomographies were obtained before and after canine traction and the inclination and position of both maxillary central incisors were measured. Furthermore, dental arch, skeletal, and canine impaction characteristics were evaluated. Paired and independent t tests were used for intra and inter group comparisons, respectively. Multiple linear regressions were also used. RESULTS: After canine traction, a significant incisor labial inclination was observed in the bilateral group (10.41° right side, P = 0.008 and 12.79° left side, P = 0.001), while in the unilateral group, this was observed only on the nonaffected side (6.67°, P = 0.008). Furthermore, a significant protrusion of incisors was observed in the bilateral group (2.66 mm right side, P = 0.006, and 3.15 mm left side, P = 0.001) and in the nonaffected side of the unilateral group (1.74 mm, P = 0.022). Intergroup comparisons showed greater values of incisor labial inclination for the bilateral group when compared with the unilateral group, independently of the sides. CONCLUSIONS: Traction of maxillary impacted canines, in nonextraction treatment, produces greater labial inclination of maxillary incisors in bilateral cases and similar protrusion in both unilateral and bilateral cases. Unilateral impaction cases showed significant incisor inclination and protrusion in the nonaffected side. These treatment effects should be considered by clinicians.

Influence of impacted maxillary canine orthodontic traction complexity on root resorption of incisors: A retrospective longitudinal study.

INTRODUCTION: The orthodontic traction of impacted canines is a procedure of variable complexity. The objective of this study was to determine the influence of this complexity on the root resorption (RR) of adjacent incisors, using cone-beam computed tomography. METHODS: This longitudinal retrospective study included 45 patients (19 female, 11 male; ages, 18.16 ± 7.3 years) with maxillary impacted canines, classified into 2 groups according to the level of orthodontic traction complexity: low complexity group (n = 20) and high complexity group (n = 25). The amounts of RR of 45 maxillary central and 45 lateral incisors were evaluated before and after treatment. Complexity was defined considering impaction sector, eruption inclination angle, and canine position (palatal, buccal, or bicortical). Three orthodontists measured RR in each maxillary incisor. Independent t tests or Mann-Whitney U tests were used to compare resorption between groups depending on the normality of the data. A multiple linear regression was calculated to evaluate the influence of all variables on RR (α = 0.05). RESULTS: RR of maxillary incisors in the sagittal, coronal, and axial sections showed no significant differences between groups (P > 0.05). Independently of the groups, RR ranged approximately from 1 to 1.5 mm and from 3 to 4 mm2. RR was less than 2 mm2 in the axial sections. Multiple linear regression indicated no significant influence of orthodontic treatment complexity on RR. Male patients had more RR, specifically in the maxillary central incisors than female patients (P < 0.05). CONCLUSIONS: The complexity of orthodontic traction of impacted maxillary canines is not a risk factor for greater RR of maxillary incisors close to the impaction area.

Effect of posterior space discrepancy and third molar angulation on anterior overbite.

INTRODUCTION: In this study, we aimed to determine the effect of maxillary and mandibular posterior space discrepancies and third molar angulations on the overbite. METHODS: Pretreatment lateral cephalograms of 131 subjects were analyzed. The sample included 83 open-bite and 48 deepbite subjects. A multiple regression analysis was used to evaluate the influence of maxillary and mandibular posterior space discrepancies and third molar angulations (predictor variables) on overbite. Correlations between posterior space discrepancy and third molar angulation, and correlations between predictor variables and dental angulation and height of posterior teeth and incisors were evaluated with the Pearson correlation coefficient. Subgroups with accentuated negative overbite and deepbite (27 open-bite, 37 deepbite) were compared with t tests. RESULTS: The multiple linear regression analysis showed a positive association of the mesial angulation of the mandibular third molar with overbite. Posterior space discrepancy was negatively associated with posterior teeth mesial angulation and dentoalveolar height. However, these associations were weak, with no clinically significant implications. The deepbite subgroup showed significantly greater mesial angulation of the mandibular third molars than did the open-bite subgroup. CONCLUSIONS: There was no clinically significant effect of posterior space discrepancies and third molar angulations on overbite and dental angulation and height of posterior teeth and incisors.

Maxillary transverse dimensions in subjects with and without impacted canines: A comparative cone-beam computed tomography study.

INTRODUCTION: The objective of this study was to compare the maxillary transverse dimensions between subjects with impacted maxillary canines and subjects without canine impactions, with similar vertical and sagittal features. METHODS: In this retrospective study, 86 cone-beam computed tomography images of subjects with impacted maxillary canines (45 unilateral, 41 bilateral) and 67 images of subjects without dental impactions (control group) matched by similar vertical (NSAr, SArGo, ArGoMe) and sagittal (ANB, SNA, APDI) skeletal characteristics, were analyzed. The maxillary width was measured at 4 levels: first molar basal width, first molar alveolar width, first premolar basal width, and first premolar alveolar width. Group comparisons were performed with analysis of variance and post-hoc Scheffé tests. The influence of group features on the transverse dimensions was evaluated by a multiple linear regression analysis. RESULTS: Groups with unilateral and bilateral impacted maxillary canines showed significantly smaller first molar basal widths, first molar alveolar widths, and first premolar alveolar widths compared with the control group (P = 0.030, P <0.001, and P <0.001, respectively). First premolar basal widths were not significantly different among the groups. CONCLUSIONS: Subjects with unilateral or bilateral impacted maxillary canines have smaller maxillary transverse dimensions than do subjects without impaction. Orthodontists should consider the relationship of maxillary width and canine impaction during diagnosis and treatment planning.

Root resorption of maxillary incisors after traction of unilateral vs bilateral impacted canines with reinforced anchorage.

INTRODUCTION: The aim of this study was to compare the root resorption (RR) of maxillary incisors after traction of unilateral vs bilateral impacted canines with reinforced anchorage. METHODS: This retrospective longitudinal study included 60 cone-beam computed tomography scans of patients with maxillary impacted canines: 30 scans taken before and 30 taken after orthodontic traction with nickel-titanium coil springs. Two groups were formed according to the impaction condition: 15 with unilateral maxillary impacted canines and 15 with bilateral maxillary impacted canines. Three trained orthodontists made the measurements. Demographic variables, occlusal characteristics, skeletal class, and measurements related to canine impaction were collected from the clinical history, dental models, and radiographs of each patient. RR (mm and mm2) for each maxillary incisor was measured in 3 dimensions. Independent t or Mann-Whitney U tests were used, depending on data normality. Multiple linear regression analyses were used to evaluate the influence of all variables (predictors) on RR (α = 0.05). RESULTS: RR did not show significant differences between groups in any section (P > 0.05). No subject had RR greater than 2 mm or 5 mm2. The specific influence of some predictor variables varied depending on the type of maxillary incisor. CONCLUSIONS: RR of maxillary incisors after traction of unilateral vs bilateral impacted canines with reinforced anchorage was similar and is not a risk to the integrity of the maxillary incisor root.

Influence of maxillary posterior discrepancy on upper molar vertical position and facial vertical dimensions in subjects with or without skeletal open bite.

OBJECTIVES: To determine the influence of maxillary posterior discrepancy on upper molar vertical position and dentofacial vertical dimensions in individuals with or without skeletal open bite (SOB). MATERIALS AND METHODS: Pre-treatment lateral cephalograms of 139 young adults were examined. The sample was divided into eight groups categorized according to their sagittal and vertical skeletal facial growth pattern and maxillary posterior discrepancy (present or absent). Upper molar vertical position, overbite, lower anterior facial height and facial height ratio were measured. Independent t-test was performed to determine differences between the groups considering maxillary posterior discrepancy. Principal component analysis and MANCOVA test were also used. RESULTS: No statistically significant differences were found comparing the molar vertical position according to maxillary posterior discrepancy for the SOB Class I group or the group with adequate overbite. Significant differences were found in SOB Class II and Class III groups. In addition, an increased molar vertical position was found in the group without posterior discrepancy. LIMITATIONS: Some variables closely related with the individual's intrinsic craniofacial development that could influence the evaluated vertical measurements were not considered. CONCLUSIONS AND IMPLICATIONS: Overall maxillary posterior discrepancy does not appear to have a clear impact on upper molar vertical position or facial vertical dimensions. Only the SOB Class III group without posterior discrepancy had a significant increased upper molar vertical position.