Rohan Mascarenhas

Kissing molars: An unusual unexpected impaction

Impacted molars have been widely reported. However, kissing molars is a rare finding which refers to impacted molars which have occlusal surfaces contacting each other in a single follicular space and roots pointing in opposite directions as reported in this case. This is the second case of kissing molars involving third and fourth molar and the only case fulfilling the criteria of kissing molars.

Facial talon in mandibular incisor: An unusual occurrence

Talon cusp, also known as an eagles talon, is a dental anomaly that occurs on the lingual aspect of teeth commonly, but occurrence on the facial aspect has rarely been reported. It is an extra cusp on an anterior tooth, which arises as a result of evagination on the surface of a crown before calcification has occurred. The incidence of talon cusp on lingual side is less than 6% and is even lesser on the facial aspect. Commonly involved teeth are maxillary incisors, usually unilateral but in some instances bilateral. The classical radiographical feature of talon cusp is double teeth appearance. The anomaly has been reported to be unusual in the mandibular dentition and extremely rare on the facial aspect. We report one such extremely rare case of facial talon cusp in mandibular central incisor.

Effect of intrusive and retraction forces in labial and lingual orthodontics: A finite element study

Objectives: Lingual orthodontics differs in biomechanics as compared to labial system and has biomechanical advantages. Although theoretical approaches have explained the differences between labial and lingual orthodontics, the finite element method (FEM) may be better suited to analyze these differences. This study analyzes the effect of vertical and horizontal forces together on the tooth using FEM. Materials and Methods: An extracted right maxillary central incisor was radiographed and was used to create a solid model using ANSYS. The geometric model was converted into a finite element model with the help of ANSYS software. The model consists of 27,000 elements and 30,000 nodes. Two force vectors (vertical and horizontal) were applied labially and lingually at 3 different heights- 4 mm, 5 mm and 6 mm from the incisal edge. Results: In the labial system, the net force vector passes through the center of resistance (CR) and brings about intrusion. The net force vector in lingual orthodontics does not pass through the center of resistance and produces lingual tipping of the incisors. Conclusion: Intrusion and retraction forces bring about tipping of incisors in lingual orthodontics. The same amount of intrusion and retraction forces brings about intrusion of incisors in labial orthodontics. Therefore, direction and amount of forces should be carefully and judiciously applied after taking into consideration the resultant biomechanical differences.

Clinical Application of Micro-Implant Anchorage in Initial Orthodontic Retraction

Micro-implant is a device that is temporarily fixed to bone for the purpose of enhancing orthodontic anchorage either by supporting the teeth of the reactive unit or by obviating the need for the reactive unit altogether, and which is subsequently removed after use. The purpose of this study was to evaluate the clinical efficiency of micro-implants in reinforcing anchorage during the initial retraction of anterior teeth, check the rate of initial retraction for 8 weeks, and assess the stability of micro-implants during this period. Eighteen micro-implants were placed (10 in the maxilla and 8 in the mandible) and immediately loaded with 200-250 g of force using 9-mm closed coil Nitinol springs. The amount of space closure was measured every 2 weeks until the eighth week. Cephalometric measurements were made at the end of the study to evaluate anchor loss, if any. Micro-implant stability was also assessed. The rate of initial retraction in the maxilla at the end of 8 weeks was 1.65 mm/quadrant and 1.51 mm/quadrant in the mandible. The amount of retraction on the left side of the arches was 1.66 mm/quadrant and 1.49 mm/quadrant on the right side. The average initial retraction for both arches per month was 0.78 mm. An anchor loss of 0.1 mm (0.06%) was observed in the maxilla while no mandibular anchor loss was recorded. The rate of initial retraction observed in the maxilla was more than that achieved in the mandible. Initial retraction was also more on the left side of the arches. There was no anchor loss in the mandible. The micro-implant-reinforced anchorage was helpful in minimizing anchor loss and accepted heavy traction forces but did not bring about a faster rate of retraction.

Evaluation of Lingual Orthodontic appliances

Due to increasing popularity of lingual orthodontics in recent years, various lingual systems have been developed. In orthodontics Finite Element Method (FEM) has been used to study various types of tooth movement. Although FEM was extensively used for evaluating the biomechanical effects of labial orthodontic forces, research on lingual system is still limited. The purpose of this study is to evaluate the efficacy of two different lingual bracket systems using FEM. FEM of maxilla which included six upper anterior teeth, periodontal ligament has been created. Six upper anterior teeth were digitally arranged in final position using a new computerized method. CAD models of six upper anterior brackets of 7 generation and Lingual matrix have also been created and attached onto the digital model at appropriate heights. Various orthodontic movements were simulated and force applied distal to the canine bracket. Deformation, stress on teeth, bone and periodontal ligament were studied and compared between the two different lingual systems. Deformation was less with lingual matrix brackets than 7 generation brackets when subjected to intrusive, retractive and combined forces. More stresses were generated on the teeth, bone and PDL in lingual matrix brackets than 7 generation brackets when subjected to forces. It was found that tooth movements are more efficient and precise in lingual matrix brackets than prefabricated 7 generation brackets.

Class III molar finish as a different treatment approach to correct an adolescent Class II patient using headgear, forsus, and lower arch extraction

Various treatment strategies are adopted to correct a Class II malocclusion depending on the age, the amount of remaining growth and severity of malocclusion. Single arch extraction of the lowers is rarely done in a Class II malocclusion. The following case report describes an alternate treatment approach of an adolescent Class II patient treated with a combination of headgear, fixed functional appliance (forsus), and single arch extraction only in the lower arch. The case was finished in a Class III molar and a Class I canine relationship. The results were stable in 3 years follow-up.

Prenatal and postnatal growth: An ultrasound and clinical investigation

Background: Understanding facial development requires sound knowledge of growth at different stages. Although studies in the past have established the relationship between prenatal and postnatal growth, little research has been done using noninvasive ultrasound. The purpose of this study is to evaluate correlation between prenatal and postnatal growths using ultrasound as a fetal growth assessment tool. Study Settings: It is a hospital-based study where prenatal growth is measured at different intervals of gestational period and compared with the growth at birth. Materials and Methods: Ten subjects with normal pregnancy were studied using ultrasound. Cephalocaudal growth gradient, body proportions of the fetus were assessed and compared at different stages. Growth was also evaluated at birth and compared with the predicted growth. Results: The growth rate of estimated fetal weight is at maximum between the 28th and 32nd week of the fetal life (P ≤ 0.001). The growth rate of head circumference, occipitofrontal diameter, and femur length is maximum between the 20th and 28th week of the fetal life (P < 0.001). Cephalocaudal growth gradient decreases with increased age of the fetus. Conclusions: Prenatal growth is correlated with postnatal growth. Ultrasound can be used as a tool for the measurement and prediction of prenatal and postnatal growths.

Management of tooth size discrepancy due to previously extracted maxillary canines

This case report is of a patient whose maxillary canines had been previously extracted. She complained of severe crowding in the lower arch. Intraoral examination revealed that she had Class I molar relationship, nonocclusion in the premolar region, and cross bite. Cast analysis showed tooth size/arch length discrepancy in the lower arch and Boltons tooth size analysis showed large mandibular excess. Treatment included extraction of mandibular first premolars and fixed mechanotherapy to correct crowding, canine relation, and Boltons discrepancy. Maxillary premolars were substituted for the extracted canines. At the end of treatment, the patient had a pleasing profile, good intercuspation, ideal overjet, and overbite. Posttreatment cephalometric evaluation showed acceptable maxillary and mandibular incisor inclinations. The occlusion remained stable after orthodontic treatment.

A comparative study of forces in labial and lingual orthodontics using finite element method

Background: Orthodontic treatment requires optimum force to achieve desirable tooth movement with minimal damage to the root, periodontal ligament (PDL), and alveolar bone. Hence, quantifying the magnitude and direction of force is very important for orthodontic treatment. Both labial orthodontics (LaO) and lingual orthodontics (LiO) are used for orthodontic tooth movements, which differ considerably in their biomechanics. Although these differences have been explained, force magnitude need to be evaluated. Aims: 1. To evaluate the differences in biomechanics of tipping movement in LaO and LiO using finite element method (FEM). 2. To quantify the reduced amount of force in LiO as compared LaO in tipping. Study Settings: It is a computational tool where three-dimensional (3D) FEM models of upper incisor is simulated in order to map and compare the stress produced by tipping movement performed with lingual and LaO. Materials and Methods: A 3D FEM model of the maxillary right central incisor was made from a geometric model. A 50 g tipping force was applied on a labial side. The principal stress patterns in the PDL for orthodontic tooth movement were recorded. When 50 g of tipping force was applied from a lingual side, higher stress values were observed. The forces on the lingual side were reduced to 45 g, 40 g, 35 g, 34 g, 33.5 g, and 33 g to check the maximum stress pattern on PDL. Results: A 50 g tipping force applied on the labial side will bring about 0.0252 N/mm 2 maximum principal stress. When the same amount of force applied on the lingual side will bring about 0.0375 N/mm 2 maximum principal stress. A 33.6-g force applied on the lingual side will bring about 0.0252 N/mm 2 maximum principal stress which is similar to 50 g of force applied on the lingual side. Conclusion: A palatally directed tipping force of 33.6 g in LiO was sufficient for orthodontic tooth movement. Tipping in LiO required 32.8% less force when compared to LaO.

Orthodontic camouflage treatment in skeletal Class II patient

Orthodontic camouflage is a method of correcting malocclusion without involving the correction of skeletal problem. Planned extraction of some teeth will help us achieve favorable dental occlusion. The challenge lies in proper diagnosis and case selection so as to decide on dental camouflage as a treatment option in skeletal discrepancy cases. Case of Class II malocclusion with severe crowding, vertical growth pattern and Class II skeletal base with ANB 6° has been discussed. Treated with four premolar extractions and finished the case with Class I canine and molar relationship. Planned extraction of indicated teeth to bring about dental compensation and camouflage the underlying skeletal discrepancy gives an overall improvement in facial esthetics, occlusion and also satisfaction to the patient.