3-D Evaluation of temporary skeletal anchorage sites in the maxilla.

BACKGROUND: The selection of temporary anchorage device (TAD) site can be a challenging task since one should not only consider the 2-D distances between roots, but also the entire 3-D space. Thus, the aim of this study was to evaluate the posterior maxillary region areas available for the insertion of temporary anchorage devices in reconstructed images from cone beam computed tomography (CBCT). MATERIAL AND METHODS: Sample consisted of 72 patients with indication for orthodontic treatment, grouped into three distinct age groups: 11 to 14 years (age group 1), 15 to 19 years (age group 2) and aged 20 years or older (age group 3), which were further subdivided as to the type of malocclusion (Angle Class I, II and III). Orthopantomographic reconstructions and cross sections were obtained with the Dolphin Imaging software. The distance between the roots of maxillary teeth (canines, premolars and first molars) was determined at 5 mm of the cementoenamel junction, as well as the depth of bone availability at different insertion angles (90°, 75°, 60°, 45°). The influence of different angulations, age, and malocclusion on bone availability was evaluated by ANOVA, followed by the Bonferroni post-test. For the evaluation of the interaction of these factors, 2-way ANOVA was used. RESULTS: Bone availability was found to be poor between roots in the molar region. There was a reduction in bone availability with increasing age. With regard to angulations, greater bone availability was found in depth for 45° angulation in the canine and first premolar regions and for angulation of 75° or 90° in the molar region. However, there was no difference between bone availability in the region of the second premolars. CONCLUSIONS: According to applied methodology it can be concluded that the region between canines and premolars accepts better vertical angular variations for TADs insertion. Key words:Cone-Beam Computed Tomography, Orthodontic Anchorage Procedures.

Treatment Time of Class II Malocclusion, with and without Mandibular Crowding, Treated with Four Premolar Extractions: A Retrospective Study.

OBJECTIVE: This study aimed to compare the treatment times in patients with complete bilateral Class II malocclusion, with and without mandibular crowding, treated with 4 premolar extractions. METHODS: The sample comprised 57 retrospectively and consecutively selected patients (30 male, 27 female) treated for initial Class II malocclusion, divided as follows: Group 1 consisted of 23 patients (11 males, 12 females; mean age 13.13 years) presenting no crowding or 3 mm at most. Group 2 consisted of 34 patients (19 males, 15 females; mean age13.06 years) presenting more than 4 mm of crowding. Crowding was manually measured in the initial dental casts. The Objective Grading System (OGS) index was manually measured in the final dental casts and radiographic images. The groups were comparable regarding initial age, gender distribution, and final occlusal statuses. The treatment times between the groups were compared using the t-test. Correlation between crowding and treatment time was evaluated with Pearson correlation coefficient. RESULTS: Treatment times between the 2 groups were similar (P = .890) and there was no significant correlation between the amount of crowding and treatment time (r = 0.04, P = .760). CONCLUSION: Treatment times for complete Class II malocclusion with and without mandibular crowding, treated with 4 premolar extractions, are similar.

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.

Posterior teeth angulation in non-extraction and extraction treatment of anterior open-bite patients.

BACKGOUND: This study cephalometrically evaluated the posterior teeth angulation changes of anterior open-bite non-extraction and extraction treatment in the permanent dentition, with anterior vertical elastics. METHODS: The sample consisted of initial and final lateral headfilms of 60 patients divided into 2 groups: Group 1 consisted of 30 patients treated with non-extraction with an initial mean age of 15.26 years and treated with fixed appliances for a mean period of 2.46 years. Group 2 consisted of 30 patients treated with extractions, with an initial mean age of 14.03 years, and treated with fixed appliances for a mean period of 2.49 years. Within-group treatment changes were evaluated with paired t tests. Results were considered statistically significant at P < 0.05. RESULTS: The mandibular posterior teeth were significantly uprighted in both groups with both treatment protocols. CONCLUSIONS: Correction of anterior open bite with either non-extraction or extractions with continuous archwires and vertical anterior elastics uprights the mandibular posterior teeth.

Posterior tooth angulations in patients with anterior open bite and normal occlusion.

INTRODUCTION: The aim of this study was to compare the posterior tooth angulations in patients with open-bite malocclusion and normal occlusion. METHODS: Lateral cephalometric headfilms of 45 untreated open-bite subjects were compared with the lateral headfilms of 45 subjects with normal occlusion in the permanent dentition. The groups were matched for age and sex distribution and compared with t tests. RESULTS: The maxillary and mandibular premolars were more mesially angulated in relation to the bisected occlusal plane, and the first and second molars were significantly more distally angulated in the open-bite group in relation to the palatal and mandibular planes. CONCLUSIONS: The maxillary and mandibular premolars were more mesially angulated in relation to the bisected occlusal plane and therefore do not compensate for the divergence of the palatal and mandibular planes as the molars do.