Influence of the third molar presence on the thickness and height of the buccal cortical bone of the mandibular first and second molars.

Background: This study aimed to evaluate the influence of the presence of the third molars on the thickness and height of the buccal cortical bone of the first and second mandibular molars. Material and Methods: The retrospective cross-sectional observational sample consisted of 102 CBCTs of patients (mean age of 29 years), divided into two groups: G1: 51 patients (26 female; 25 male, mean age of 26 years) presenting the mandibular third molars and G2: 51 patients (26 female; 25 male, mean age of 32 years) with the absence of the mandibular third molars. The total and the cortical depth were evaluated at 4 and 6mm from the cementoenamel junction (CEJ). The total thickness of the buccal bone was evaluated in two horizontal reference lines located apically 6 mm and 11 mm from the CEJ. Statistical comparisons were performed with Mann Whitney and Wilcoxon tests. Results: In the comparison of buccal bone thickness and height between the groups, there was a statistical difference in tooth 36. In tooth 37 there was a statistical difference in the mesial root. For tooth 47, there was a statistical difference for the total thickness at 6mm, 11mm and 4mm. Concerning age, there was a tendency to decrease the values of these variables with increasing age. Conclusions: The mean values for buccal bone thickness, total and cortical depth of the mandibular molars were higher for patients with mandibular third molars because the buccal bone thickness of the mandibular molars increased in the posterior and apical direction. Key words:Molar tooth, jaw, bone, orthodontic anchorage procedures, cone-beam computed tomography.

Stability of transversal correction with hybrid maxillary expansion appliance in bone and tegumental piriformis opening in relation to bone age and maturation of the midpalatal suture.

Background: To evaluate the stability of the transverse correction with a hybrid maxillary expansion appliance in the bone and tegumental piriformis opening in relation to bone age and maturation of the midpalatal suture (MPS). Material and Methods: 15 patients with a mean initial age of 14.9 years (SD=1.50), 7 (46.7%) were female and 8 (53.3%) were male, treated with a hybrid maxillary expander. Cone beam computed tomographic (CBCT) images were collected in three phases: T1 (orthodontic records), T2 (21.33 days (SD=10.68) after the end of expansion screw activation) and T3 after 9.13 months (DP=2.41) after the expansion screw was activated. In CBCT, measurements were performed in the nasal cavity considering the tegumental piriform opening (sagittal-axial sections) and bone (sagittal-axial-coronal sections) and the stage of MPS maturation (sagittal-axial sections). Repeated measures ANOVA was used for continuous variables and Friedman's ANOVA for the ordinal variable followed by Bonferroni's tests for p<0.001, in relation to time. Results: There were significant differences between T1 and T2 (p=0.041), between T2 and T3 (p<0.001) and between T1 and T3 (p=0.041). Regarding bone age by cervical vertebrae maturation, 20% were in stage CS3, 40% in stage CS4, 26.7% in stage CS5 and 13.3% in stage CS6. There was a significant increase in tegumental piriformis opening between T1 (M=32.19, SD=3.79) and T2 (M=34.82, SD=2.81) (p=0.008), followed by a significant decrease in T3 (M=34.64, SD=2.73) (p=0.021), as well as in the opening of the bone piriform, between T1 (M=21.30, SD=2.47) and T2 (M=25.35, SD=2.21) (p<0.001), followed by a significant decrease in T3 (M=24.89, SD =2.30) (p=0.018). Conclusions: The hybrid maxillary expansion appliance was effective in opening the midpalatal suture of all patients in the present study, without influence of the initial stage of MPS maturation and bone age. There was a relapse of the increase in the bone and tegumental piriform openings. Key words:Maxillary expansion, orthodontic anchorage procedures, nose.

Using the HERBST appliance with atypical extractions in the lower dental arch.

This article reports the case of a patient with severe mandibular deficiency and crowding in the mandibular arch treated with atypical extractions of two premolars followed by mandibular advancement with the Herbst appliance. It became clear that this therapy corrected the malocclusion while improving facial.

New perspective on Herbst therapy for skeletal Class II malocclusions: a proposal for maxillary protrusion management.

Angle Class II malocclusions may present morphologic deviations originated from the maxilla, mandible, or both. Since its reintroduction by Pancherz, the Herbst appliance has demonstrated effectiveness in the management of patients with mandibular deficiency. Because of the intermaxillary anchorage, the action of mandibular advancement provokes simultaneous reaction of maxillary restriction, similar to high-pull headgear. This aimed of this report is to compare two cases treated in two phases. In the first interceptive phase, the transverse problem was corrected by rapid maxillary expansion, which was followed by a Herbst appliance for mandibular advancement; in the second corrective phase, the cases were finished with fixed appliances. Although Herbst appliances were used in both patients, one patient with maxillary protrusion and another with mandibular deficiency, their use targeted different types of skeletal discrepancies. This difference allowed for the comparison of treatment effects, and although both patients had their malocclusion corrected, it seems reasonable to conclude that the final outcome was more favorable for the patient with maxillary protrusion.

Orthodontic-surgical treatment of Class III malocclusion with extraction of an impacted canine and multi-segmented maxillary surgery.

Establishment of a treatment plan is based on efficacy and easy application by the clinician, and acceptance by the patient. Treatment of adult patients with Class III malocclusion might require orthognathic surgery, especially when the deformity is severe, with a significant impact on facial esthetics. Impacted teeth can remarkably influence treatment planning, which should be precise and concise to allow a reasonably short treatment time with low biologic cost. We report here the case of a 20-year-old man who had a skeletal Class III malocclusion and impaction of the maxillary right canine, leading to remarkable deviation of the maxillary midline; this was his chief complaint. Because of the severely deviated position of the impacted canine, treatment included extraction of the maxillary right canine and left first premolar for midline correction followed by leveling, alignment, correction of compensatory tooth positioning, and orthognathic surgery to correct the skeletal Class III malocclusion because of the severe maxillary deficiency. This treatment approach allowed correction of the maxillary dental midline discrepancy to the midsagittal plane and establishment of good occlusion and optimal esthetics.