Correlation of mandibular third molar orientation and available retromolar space with arch length discrepancy in subjects with different growth pattern.

Aim and Objective: To evaluate, compare, and correlate the mandibular third molar orientation and available retromolar space with arch length discrepancy in subjects with skeletal class II malocclusion and different growth pattern. Material and Method: A total of 250 patients (age >18 yrs) having skeletal class II malocclusion (based on YEN angle and WITS appraisal) were divided into two groups. Both the groups (Group I with erupted mandibular third molars {N = 150} and Group II with impacted mandibular third molars {N = 100}) were subdivided into subgroups IA (n = 71), IB (n = 19), IC (n = 71) and Group IIA (n = 54), IIB (n = 30) and IIC (n = 16) for normo-, hypo- and hyperdivergent growth patterns, respectively (based on Jarabak ratio and Sn-Go-Gn angle). Four parameters, that is, retromolar space, width of third molar, third molar angulation, and mandibular incisor angulation were measured on orthopantomogram whereas arch length discrepancy was calculated with the help of lateral cephalogram and study model. Intragroup, intergroup comparisons (using unpaired Student's 't' test), and Pearson's correlation coefficient for assessed parameters were obtained. Result: Third molar angulation and retromolar space were significantly higher in Group I than in Group II (hyperdivergent pattern of Group II had highest value). The width of third molar was less than retromolar space in Group II and vice versa for Group I. Mandibular incisor angulation and arch length discrepancy were more in Group II than in Group I, but difference was statistically nonsignificant. Strong positive correlation was observed for mandibular third molar angulation and available retromolar space in normo- and hyperdivergent growth patterns. Conclusion: Lack of retromolar space along with increased amount of arch length discrepancy and mandibular incisor angulation is responsible for increased chances of third molar impaction in some subjects with class II malocclusion.

Predictive accuracy of estimating mandibular growth potential by regression equation using cervical vertebral bone age.

INTRODUCTION: The maturational changes both in size and shape of cervical vertebrae had been widely used not only to assess skeletal maturity but also to predict the same using regression equation. Thus, the aim of this cross-sectional study was to check the predictive accuracy of estimating mandibular growth potential in the North Indian population by regression equation of Mito et al. MATERIALS AND METHODS: A total of 200 subjects divided into two groups, Group I had 100 adult subjects (18-20 years) and Group II had 100 young subjects (9-14 years) were subdivided according to the gender (50 subjects in each group). Seven linear parameters on cervical vertebral bodies of C3 and C4 were measured to derive cervical vertebral age and applied to the regression equation to estimate the mandibular growth potential in Group II. The mandibular length was measured for both the groups from Co-Gn. The mean value of the actual mandibular length in Group I was statistically evaluated against the corresponding mean value of the predicted mandibular growth potential of Group II. RESULTS: The actual mandibular length (Group I) and calculated mandibular length obtained by adding mandibular growth potential (from regression equation) to the mandibular length of Group II did not differ significantly for both males and females. Chronological age showed a statistically significant difference and poor correlation with bone age, in Group II. CONCLUSION: The regression equation of Mito et al. using cervical vertebral bone age has proven to be applicable and accurate in predicting mandibular growth potential in growing young Indian individuals and can be of diagnostic and prognostic value in growth modification procedures in Orthodontics.

Load-deflection characteristics of coated and noncoated nickel-titanium wires in self-ligating brackets using a modified bending test: An in vitro study.

BACKGROUND: To determine and compare the force-deflection values of different types of nickel-titanium (NiTi) wires during unloading phase at varying deflections, that is 1 mm, 1.5 mm, 2 mm, and 2.5 mm, with the use of self-ligating ceramic brackets using modified bending test on a typodont under controlled temperature conditions. MATERIALS AND METHODS: In this in vitro study total of 45 wires of ovoid shape of three different NiTi wires - pseudoelastic NiTi (Group I), heat activated NiTi (Group II), and esthetic coated NiTi (Group III) for maxillary arch were tested after insertion in ceramic self-ligating brackets bonded to plastic teeth of phantom jaw. The maxillary left lateral incisor was removed to simulate a malpositioned tooth which acted as the load site, and load-deflection characteristics were measured during unloading using Instron, and data analyzed statically by two-way analysis of variance, Tukey's post hoc test, intraclass correlation coefficient and Pearson correlation coefficient. A two-sided (α = 2) P < 0.05 was considered statistically significant. RESULTS: When wires were compared at each deflection statistically significant difference was observed between the three groups of wires (Group I > Group II > Group III) at all the four levels of deflection except for Group II versus Group III at 1 mm, 1.5 mm, and 2 mm of deflection. Statistically significant difference was noted in mean load values for comparisons made at different deflections for each wire except for the comparison made at 1.5 versus 2 mm for Group II and Group III. CONCLUSION: Overall comparison showed esthetic coated Ni-Ti wires gave significantly lower mean load values, followed by heat activated and pseudoelastic NiTi wires. Thus, heat activated NiTi wires are best suited in patients with severe malpositions/periodontitis, while for esthetically conscious patients esthetic coated NiTi can be used.

Release of nickel and chromium ions in the saliva of patients with fixed orthodontic appliance: An in-vivo study.

INTRODUCTION: Various components of fixed orthodontic appliances are continuously interacting with saliva and other fluids in the mouth releasing various metal ions including nickel and chromium that can cause damaging effects if their concentration exceeds above the toxic dose. AIM: To determine and compare the level of nickel and chromium in the saliva of patients undergoing fixed orthodontic treatment at different time periods. MATERIALS AND METHODS: The sample of saliva of 13 patients was taken at different time periods that is: Group 1 (before appliance placement), Group II, III, and IV (after 1-week, 1-month, and 3 months of appliance placement respectively). The fixed appliance comprised of brackets, bands, buccal tubes, lingual sheath, transpalatal arch and wires composed of Ni-Ti and stainless steel. The level of ions was determined using graphite furnace atomic absorption spectro-photometry. The data thus obtained were statistically analyzed using SPSS Statistical Analysis Software (Version 15.0). RESULTS: Level of nickel and chromium in saliva was highest in Group II and lowest in Groups I for both the ions. On comparison among different Groups, it was statistically significant for all the groups (<0.001) except between Group III and Group IV. CONCLUSION: The release of nickel and chromium was maximum at 1-week and then the level gradually declined. These values were well below the toxic dose of these ions. The results should be viewed with caution in subjects with Ni hypersensitivity.

Ortho-surgical management of skeletal Class III malocclusion.

Class III malocclusions are considered to be one of the most difficult problems to treat. Establishment of the treatment plan is based on the efficacy and thoughtful application by the clinician and easy acceptance by the patient. We are presenting a case report of an adult male patient with skeletal Class III malocclusion who was treated by orthosurgical approach in Department of Orthodontics in collaboration with Department of Oral and Maxillofacial Surgery. The treatment was complete with a positive overbite and acceptable occlusion and satisfactory facial esthetics using a combination approach.

Cephalometric norms for orthognathic surgery in North Indian population using Nemoceph software.

BACKGROUND: Cephalometric norms, useful in providing guidance to orthodontist during diagnosis and treatment planning are subjected to variability in morphologic characteristics in different ethnic and racial groups, hence norms established for one population group are not applicable for all. AIMS AND OBJECTIVES: To compare and correlate the established hard tissue cephalometric norms for orthognathic surgery (COGS analysis) given by Legan and Burstone with norms obtained for North Indian population. METHODS: Pre-treatment digital lateral cephalograms of 100 orthodontically untreated subjects having pleasing profile and normal occlusion in the age range of 18-25 yrs (mean age of 21 ± 2.62 years) were selected. 16 linear and 6 angular hard tissue parameters of COGS analysis were analyzed using nemoceph software for the males and females separately. The data obtained were compared with previously established norms for Orthognathic Surgery using SPSS Version 15.0. RESULTS: North Indian males and females had smaller anterior cranial base length with prognathic maxilla and mandible, protrusive chin with poor chin form, decreased facial height, decreased posterior maxillary height with anticlockwise rotation of mandible, increased anterior and posterior maxillary dental heights, decreased ramal and corpus length, clockwise rotation of occlusal plane, presence of sagittal discrepancy between maxillary and mandibular denture bases in comparison to Caucasian males and females respectively. North Indian females had more proclination of mandibular incisors than Caucasian females. Sexual dimorphism was also evident in the present study with males exhibiting significantly larger cranial base length, greater middle third facial height and posterior maxillary height, counterclockwise rotation of mandibular plane, greater anterior and posterior mandibular dental heights and longer ramal and corpus length in comparison to females. CONCLUSION: North Indian population showed significant differences in facial morphology as compared to Caucasians population. Sexual dimorphism was also evident in North Indian populations. Thus the need to develop separate Orthognathic Surgical norms for better treatment planning of North Indian population is justified.

Dimensional changes in maxillary sinus of mouth breathers.

AIMS: Nose being the primary mode of air intake in humans can be obstructed in certain conditions and mouth takes over the process of breathing. As a result, there is a reduced or complete loss of function of nose, which shows underdevelopment or stunted growth (change in form). This can lead to impaired pneumatization that can result in dimensional changes in the sinus. OBJECTIVE: To assess volume alterations in maxillary sinus as secondary and as compensatory mechanism to altered functional matrices by comparing overall maxillary sinus volume of mouth breathers with normal breathers in the age group 12-14 years and to evaluate effect of gender on maxillary sinus volume. MATERIAL AND METHOD: Maxillary sinus volume calculated using manual segmentation method from CBCT scans of 25 normal breathers and 25 mouth breathers were compared. RESULTS: Mean maxillary sinus volume of mouth breathers was significantly less than normal breathers (p < 0.05). CONCLUSION: Mouth breathers showed lesser maxillary sinus volume but it is still uncertain whether the reduction in the volume of maxillary sinus is because the form of the maxillary sinus is affected due to improper functioning of nasal cavity or due to the underlying pathological condition resulting in poorly growing sinus.

Role of buccal corridor in smile esthetics and its correlation with underlying skeletal and dental structures.

PURPOSE: This study was designed to evaluate the buccal corridor in smile esthetics and to correlate it with underlying hard tissues. MATERIALS AND METHODS: Posed smiling frontal photographs, digital posterior-anterior (PA) cephalograms, and study models of 25 males and 25 females in age range of 18-25 years were taken. Photographs were evaluated for smile esthetics by eight orthodontists, eight plastic surgeons, eight beauticians and eight lay people to group them into three groups with least attractive, average and attractive smile and buccal corridor width was measured. Digital PA cephalograms were transferred on Nemo-tech software for frontal facial analysis. Intercanine and intermolar widths were measured on upper study model with the help of a digital calliper. RESULTS: The buccal corridor width was least in attractive smile group and maximum in least attractive smile group. The buccal corridor width had a negligible correlation with hard tissues and a mild to moderate inverse correlation with intercanine and intermolar widths within the groups. CONCLUSION: As the amount of buccal corridor display was increased, smiling images were scored less attractive by the evaluators. The buccal corridor is not influenced by underlying skeletal hard tissues but have mild to moderate inverse correlation with the intercanine and intermolar width.

Nasomaxillary complex in size, position and orientation in surgically treated and untreated individuals with cleft lip and palate: A cephalometric overview.

BACKGROUND: This cross-sectional retrospective cephalometric study was designed to clarify whether the maxillary deficiency seen in surgically treated individuals with non-syndromic complete unilateral cleft lip and palate (UCLP) is due to inherent growth potential or iatrogenicity. MATERIALS AND METHODS: 72 adult individuals were randomly selected in the age range of 12-20 years, and were divided into two groups. Group I had 47 untreated individuals. Group II consisted of 25 surgically treated individuals. Lateral and frontal cephalograms of the selected individuals were taken and analysed using Nemoceph software. RESULTS: Group II showed a marked reduction in the cranial base angle, maxillary base length, anterior and posterior maxillary positions, palatal plane angle, maxillary width, maxillary height, occlusal plane height, nasal width and nasal height. CONCLUSION: Surgical intervention does interfere with growth in the facial region. This could be attributed to the scar tissue in lip and palate region, which has a restraining effect on growth in the facial region. These altered functional matrices play a significant role in determining the growth of facial structures.