Inclination Of Posterior Teeth Research Articles

Three-dimensional analysis of posterior tooth inclinations in transverse and sagittal relationships: A cross-sectional study

To compare tooth inclinations in different sagittal skeletal patterns and transverse maxillary relationships three-dimensionally. A cross-sectional study carried out with 132 three-dimensional digital models in the complete permanent dentition divided into six groups (n=22); three groups with maxillary atresia: G1- skeletal class I, G2- skeletal class II and G3-skeletal class III; three groups without maxillary atresia: G4- skeletal class I; G5- skeletal class II and G6- skeletal class III. The comparison between the skeletal pattern was performed by the non-parametric tests of Kruskal Wallis and Dunn and between the groups by the non-parametric test of Mann Whitney. Subjects with skeletal class II and maxillary atresia had a greater lingual inclination of the maxillary teeth than those with class I and III; Subjects with skeletal class II without atresia had a less lingual inclination of the mandibular molars than the other classes (p<0.05). The maxillary premolars showed no variation in dental inclination with atresia, independent of the skeletal class in G1, G2, and G3 (p>0.05). The mandibular premolars showed that the groups without atresia G4, G5, and G6 presented no significant difference (p>0.05). Lower premolars in skeletal class III malocclusion individuals with atresia had a more negative inclination than the others. There is a difference in the inclination of posterior teeth between individuals with and without maxillary atresia and skeletal classes I, II, and III.

COMPARING ARCH WIDTH, ALVEOLAR WIDTH ANDBUCCOLINGUAL INCLINATION OF POSTERIOR TEETH IN SUBJECTS WITH CLASS IANDCLASS II MALOCCLUSION

Aim: The aim of this study was to compare the arch width, alveolar width and buccolingual inclination of posterior teeth between Class I and Class II Div 1 malocclusion subjects. Materials and method: A sample of120 subjects (60 males and 60 females) in the age group of 16-19 years with Class I and Class II Div 1 malocclusion were chosen and arch width, alveolar width and buccolingual inclination of posterior teeth were measured and compared between the groups. Result: The maxillary posterior teeth showed more palatal inclination in Class II Div 1 malocclusion when compared with Class I group. Conclusion:Transverse discrepancy in Class II Div 1 might be due to more palatal inclination of maxillary posterior teeth rather than arch width and alveolar width. Hence slow maxillary expansion should be preferred for correcting the palatal inclination rather than rapid palatal expansion.

Comparative evaluation of transverse discrepancies in different sagittal malocclusions-An observational study

Introduction: Successful orthodontic treatment outcome depends on an accurate diagnosis along with clinical management of vertical and transverse discrepancies. Thus, this study is carried out to evaluate dental arch and alveolar width along with buccolingual inclination of maxillomandibular teeth in different malocclusions. Materials and Methods: Based on the Angle’s classification of malocclusion, 140 study models were selected and four separate groups were formed- normal occlusion, Class I malocclusion, Class II division 1 and Class II division 2 respectively. Maxillomandibular arch and alveolar widths at canines, 1st and 2nd premolars and first molars were measured. Buccolingual inclination of posterior teeth were measured. Lateral cephalogram of all the sample subjects was taken to calculate SNA, SNB, ANB angle, Wits Appraisal and McNamara Differential. Oneway Anova test was performed. Results: Maxillary intercanine, interpremolars, intermolar and maxillary dentoalveolar width is more in normal occlusion when compared with Class I, Class II division 1 and Class II division 2 malocclusions. Class II division 1 has narrower intercanine and interpremolar width with similar intermolar width as compared to Class II division 2. For transverse discrepancy buccolingual inclination is fundamental. Conclusion: Class II division 2 has a smaller arch width and Class II division 1 shows a significantly larger arch width than Class I malocclusions. Keywords: Arch width, Alveolar width and Buccolingual inclination.

Maxillary sinus size and posterior tooth inclination in Japanese orthodontic patients with agenesis of maxillary second premolars.

The purpose of this study was to investigate the expansion of the maxillary sinus and the inclinations of posterior teeth in orthodontic patients with maxillary second premolar agenesis. A total of 30 subjects with one or two congenitally missing maxillary second premolars and retained maxillary deciduous second molars (a agenesis group) were selected and divided into a unilateral agenesis group (20 subjects with one maxillary second premolar missing) and a bilateral agenesis group (10 subjects with two maxillary second premolars missing). As controls, 30 sex- and age-matched subjects without agenesis of the maxillary second premolars were selected. Oblique cephalograms were used to investigate the association of maxillary second premolar agenesis and lower maxillary sinus size and posterior tooth inclinations. Agenesis of the maxillary second premolars induced significantly large lower maxillary sinus length, depth, area and mesial inclination of the maxillary first premolar, a significantly small anterior maxillary length, and a significantly more distal position for root apex of the maxillary first premolar. There were no significant differences in any measurements of the lower maxillary sinus and posterior teeth between the non-agenesis side in the unilateral agenesis group and the control group. Maxillary second premolar agenesis caused inferior and anterior expansion of the lower maxillary sinus and the mesial inclination of the maxillary first premolars with a distal position of root apex. Unilateral agenesis of the maxillary second premolar did not affect on the lower maxillary sinus size or posterior tooth inclinations of the unaffected antimere.

Diagnosis of transverse problems

Traditionally, maxillary and mandibular skeletal widths and buccolingual inclination of posterior teeth are evaluated by using posteroanterior (PA) cephalogram and dental casts. However, it is difficult to identify the landmarks and make a diagnosis due to the superimposed structures on the PA cephalogram. As for the dental casts, they can neither reveal skeletal dimensions of maxilla and mandible, nor the root positions in the alveolar bone. Nowadays, the advent of CBCT enables clinicians to view craniofacial structures in three planes of space without any obstruction or superimposition of structures. In this article, a CBCT analysis on the transverse dimension is introduced. The maxillary and mandibular skeletal widths at different tooth levels, buccolingual inclination of each tooth, and their root positions in the alveolar bone can be determined. Thus, a proper transverse diagnosis can be made.

Mesially Directed Inclination of Posterior Teeth Contributing to Maxillary High Canine, and Changes during Orthodontic Treatment

Objective: The aim of study was to evaluate the nature of mesiodistal angulation of the posterior teeth in patients with maxillary high canine, and to identify possible associations of crowding with mesial axial angulation of the maxillary posterior teeth. Methods: The present study included seven Japanese male and 23 Japanese female patients. Study models were analyzed to evaluate the effectiveness of orthodontic treatment. A protractor was used to measure crown angulations, which were measured with reference to the posterior angle between the functional occlusal plane (FOP) and the long axis of the clinical crown of the lateral teeth and first molars. A sliding digital caliper was used to measure dental arch widths. Changes in the rotation of the maxillary molars were analyzed using “occlu-sograms”, which were printed from photographs of the occlusal aspect of the study model. Results: The maxillary teeth interacted with one another in the alveolar bone, resulting in progressive mesial tipping of the posterior teeth before orthodontic treatment. After orthodontic treatment, the angle relative to the FOP exhibited a significant increase, indicating that the maxillary teeth underwent distally directed uprighting (P P < 0.01). Meanwhile, the rotation of the posterior teeth did not exhibit any significant changes. Conclusions: Based on the results, both uprighting of mesially tipped lateral teeth and expansion of narrow dental arches could prove to be keys to success in space regaining or correction of high canines and mild crowding.

Maxillary expansion efficiency with clear aligner and its possible influencing factors

Objective: To evaluate the efficiency of maxillary expansion with clear aligners and to analyze the possible influence factors. Methods: Thiry-one clear aligner cases (Invisalign) with maxillary expansion were enrolled in this study. The three-dimensional (3D) digital models of pre-treatment, planned in Clincheck software and post-treatment were collected. Upper dental arch width, buccal inclination of posterior teeth, and the expansion efficiency (expansion acquired/expansion planned) were measured and calculated. The impact of factors such as planned buccal inclination, planned expansion amount, attachment, and the mode of expansion on the expansion efficiency were analyzed. Results: The increases of upper arch width in canine, 1st and 2nd premolar, 1st and 2nd molar were (2.0±1.3), (2.8±1.5), (3.0±1.4), (1.8±1.0) and 0.5 (0.1, 1.1) mm, with their efficiency of 68%, 70%, 68%, 55% and 29%, respectively. The posterior teeth showed significantly more buccal inclination than the planned position (P<0.05). However, the most buccally inclined tooth detected in 1st molars was only 3.1°±3.9°. When the planned inter-molar width increase was less than 2 mm (n=15), the expansion efficiency of premolars was higher compared with those cases with the planned inter-molar width increase more than 2 mm (n=16, P<0.05). The planned buccal inclination, attachments, and the expansion mode had no significant effect on the expansion efficiency (P>0.05). Conclusions: The expansion of maxillary arch with clear aligners was achieved by the buccal movement of the posterior teeth with limited buccal inclination. The efficiency of expansion declines from 1st premolars to second molars. The planned inter-molar width had a significant influence on the efficiency of premolar expansion.

Slow versus rapid maxillary expansion in bilateral cleft lip and palate: a CBCT randomized clinical trial.

The purpose of this "two-arm parallel" trial was to compare the orthopedic, dental, and alveolar bone plate changes of slow (SME) and rapid (RME) maxillary expansions in patients with complete bilateral cleft lip and palate (BCLP). Forty-six patients with BCLP and maxillary arch constriction in the late mixed dentition were randomly and equally allocated into two groups. Computer-generated randomization was used. Allocation was concealed with sequentially, numbered, sealed, opaque envelopes. The SME and RME groups comprised patients treated with quad-helix and Haas/Hyrax-type expanders, respectively. Cone-beam computed tomography (CBCT) exams were performed before expansion and 4 to 6months post-expansion. Nasal cavity width, maxillary width, alveolar crest width, arch width, palatal cleft width, inclination of posterior teeth, alveolar crest level, and buccal and lingual bone plate thickness were assessed. Blinding was applicable for outcome assessment only. Interphase and intergroup comparisons were performed using paired t tests and t tests, respectively (p<0.05). SME and RME similarly promoted significant increase in all the maxillary transverse dimensions at molar and premolar regions with a decreasing expanding effect from the dental arch to the nasal cavity. Palatal cleft width had a significant increase in both groups. Significant buccal inclination of posterior teeth was only observed for RME. Additionally, both expansion procedures promoted a slight reduction of the alveolar crest level and the buccal bone plate thickness. No difference was found between the orthopedic, dental, and alveolar bone plate changes of SME and RME in children with BCLP. Both appliances produced significant skeletal transverse gains with negligible periodontal bone changes. Treatment time for SME, however, was longer than the observed for RME. SME and RME can be similarly indicated to correct maxillary arch constriction in patients with BCLP in the mixed dentition.

Analysis of the dentoalveolar effects of slow and rapid maxillary expansion in complete bilateral cleft lip and palate patients: a randomized clinical trial.

The purpose of this study was to compare the dentoalveolar effects of slow (SME) and rapid (RME) maxillary expansions in patients with complete bilateral cleft lip and palate (BCLP). A sample of 50 patients with BCLP and maxillary arch constriction was randomly and equally allocated into two groups. Group SME comprised patients (mean age of 8.8years) treated with quad-helix appliance. Group RME comprised individuals (mean age of 8.9years) treated with Hyrax expander. Digital dental models obtained immediately pre-expansion (T1) and 6months after the active expansion period (T2) were used for measuring maxillary dental arch widths, arch perimeter, arch length, palatal depth, buccolingual inclination of posterior teeth and differential amount of expansion accomplished at the canine and molar regions. Inter-phase and intergroup comparisons were performed using paired t tests and t tests, respectively (p<0.05). SME and RME caused significant increase of arch widths and arch perimeter. Arch length and palatal depth decreased nonsignificantly with SME but significantly with RME. Buccal tooth inclination was significant only for maxillary deciduous canines in both groups. The quad-helix appliance showed a significant differential expansion between anterior and posterior regions. No differences were observed between SME and RME for all variables. Differences were not found between the dentoalveolar effects of SME and RME in patients with BCLP. SME demanded a greater therapy time compared to RME. Both expansion procedures can be similarly indicated to correct maxillary arch constriction in patients with BCLP in the mixed dentition.

Mandibular cephalometric characteristics of a Saudi sample of patients having impacted third molars

To evaluate the cephalometric characteristics of mandibles of Saudi patients having impacted third molars and to compare them to those of patients having normally erupted third molars. One hundred and twenty-one Saudi adult subjects (59 females and 62 males; age: 20-40 years) were divided into two groups based on the status of the mandibular third molars: (1) impaction group and (2) normal group. Means and standard deviations of 21 cephalometric measurements related to mandibular geometry were measured and compared between the two groups using the unpaired t-test. Males and females in the impaction group were also compared with their equivalent subgroups in the normal group using the unpaired t-test. Anteroposteriorly, space distal to second molar, ramal width and mandibular body length were significantly less in the impaction group than in the control group. In addition, posterior teeth were more upright in the impaction group. Vertically, posterior alveolar height was significantly less in the impaction group. The Y-axis was significantly increased in the impaction group. The significance of these measurements was variable between males and females. Third-molar impactions in the Saudis living in the Western region of Saudi Arabia were more likely to occur when inadequate retromolar space is present. This can be attributed to certain mandibular skeletal and dental features, among which the increased width of mandibular ramus and backward inclination of posterior teeth seem to be the most influencing factors in both sexes.

Alterações na dimensão transversal pela expansão rápida da maxila

As deformidades transversais, que se manifestam tipicamente pela mordida cruzada unilateral ou bilateral, são os problemas esqueléticos que mais sequelas podem causar na região craniofacial. Entretanto, são as deformidades que melhor se adaptam às alterações ortopédicas. A expansão rápida da maxila tornou-se rotina na prática ortodôntica. Embora inicialmente tenha sido utilizada na correção da mordida cruzada posterior, atualmente sua indicação ampliou-se para a expansão indireta do arco inferior, obtenção de espaço para correção de apinhamento dentário, correção axial dos dentes posteriores, melhora na estética do sorriso e auxílio no tratamento de pacientes Classe II. A expansão ortopédica da maxila vem atraindo cada vez mais a atenção da comunidade científica devido, principalmente, à sua aplicação e capacidade de alterar o crescimento craniofacial em diversas situações clínicas. Esse tipo de intervenção ortopédica possui grande utilidade terapêutica, pois sua aplicação em diversas anormalidades apresenta maior versatilidade quando comparada aos aparelhos de modificação de crescimento disponíveis atualmente para o tratamento ortodôntico.

Evaluation of the accuracy of digital model analysis for the American Board of Orthodontics objective grading system for dental casts

In 1999, after 3 years of field testing, the American Board of Orthodontics (ABO) implemented a grading system for posttreatment orthodontic models and panoramic radiographs, to make the phase III examination both fair and objective. In the ABO's objective grading system, 7 occlusal criteria (tooth alignment, vertical positioning of marginal ridges, buccolingual inclination of posterior teeth, occlusal relationship, occlusal contacts, overjet, and interproximal contacts) are measured on plaster models to assess a patient's final occlusion. To date, no study has evaluated the ABO grading system for use on digital models. The purpose of this study was to determine whether digital models can be used with reasonable accuracy and reliability for assessing patients' final occlusions. Plaster and digital (OrthoCAD, Cadent Inc, Carlstadt, NJ) posttreatment models of 24 patients were gathered from the postgraduate orthodontic clinic at Columbia University School of Dental and Oral Surgery. The plaster models were scored by using the ABO measuring gauge and the 7 criteria of the ABO grading system. A second analysis was done on the digital models. To determine interexaminer error, a fourth-year dental student at Columbia University served as a second examiner and repeated all the analyses. The means of the total score and those for marginal ridges, occlusal contacts, occlusal relationships, overjet, and interproximal contacts were not significantly different between plaster and digital models. However, the means for alignment and buccolingual inclination were significantly different. In addition, the scorings of 2 examiners differed for the 2 methods. This finding suggests that alignment and buccolingual inclination should be reevaluated with both methods, and adequate calibration of the examiners is essential to achieve repeatability in both methods. Digital models might be acceptable for use in the ABO model examination.

Buccolingual inclinations of posterior teeth in subjects with different facial patterns

This study compared the buccolingual inclination of the posterior teeth in subjects with a horizontal growth pattern (proportionally short lower anterior face height) with that of subjects with a vertical growth pattern (proportionally long lower anterior face height). Seventy subjects with permanent dentition were divided into 2 groups. Group I comprised 35 subjects (16 male, 19 female) with Class II Division 2 malocclusion with a horizontal growth pattern, and group II comprised 35 subjects (15 male, 20 female) with a vertical growth pattern. Buccolingual inclinations of the first molar and second premolar were indirectly assessed on photocopies of buccolingual sections of these teeth by measuring their occlusal surface (represented by an imaginary line connecting the lingual and buccal cusps) inclination. The groups were compared with t tests ( P < .05). The maxillary posterior teeth of subjects with a vertical growth pattern had a significantly greater buccal inclination compared with those of subjects with a horizontal growth pattern. However, there were no statistically significant differences in the inclinations of the mandibular posterior teeth between the 2 groups.