Amit Nagar

Dynamics of a smile in different age groups.

OBJECTIVE To evaluate smile in different age groups and to detect gender differences in smile. MATERIALS AND METHODS Digital videographic records of 241 randomly selected subjects were obtained for smile analysis. The subjects were divided into four groups by age (15-20 years, 21-30 years, 31-40 years, and 41-50 years). Each group was further subdivided by gender. After 41 subjects were excluded, the smile dimensions of 200 subjects were analyzed by two-way multivariate analysis of variance (MANOVA) with Duncans multiple range post hoc test. RESULTS All dynamic measurements (change in upper lip length, upper lip thickness, commissure height, and intercommissural width from rest to smile) decreased with age in both males and females. Changes in upper lip length and commissure height on smiling were greater in males as compared with females of the same age groups. Changes in intercommissural width on smiling were greater in females as compared with males in all age groups. CONCLUSION Smile changes with increase in age, and the changes differ between males and females. Females had a wider smile as compared with males of similar age groups.

A comparison of shear bond strength of orthodontic brackets bonded with four different orthodontic adhesives.

Objectives: The objective of this study is to compare the shear bond strength (SBS) of stainless steel (SS) orthodontic brackets bonded with four different orthodontic adhesives. Materials and Methods: Eighty newly extracted premolars were bonded to 0.022 SS brackets (Ormco, Scafati, Italy) and equally divided into four groups based on adhesive used: (1) Rely-a-Bond (self-cure adhesive, Reliance Orthodontic Product, Inc., Illinois, USA), (2) Transbond XT (light-cure adhesive, 3M Unitek, CA, USA), (3) Transbond Plus (sixth generation self-etch primer, 3M Unitek, CA, USA) with Transbond XT (4) Xeno V (seventh generation self-etch primer, Dentsply, Konstanz, Germany) with Xeno Ortho (light-cure adhesive, Dentsply, Konstanz, Germany) adhesive. Brackets were debonded with a universal testing machine (Model No. 3382 Instron Corp., Canton, Mass, USA). The adhesive remnant index (ARI) was recordedIn addition, the conditioned enamel surfaces were observed under a scanning electron microscope (SEM). Results: Transbond XT (15.49 MPa) attained the highest bond strength. Self-etching adhesives (Xeno V, 13.51 MPa; Transbond Plus, 11.57 MPa) showed clinically acceptable SBS values and almost clean enamel surface after debonding. The analysis of variance (F = 11.85, P < 0.0001) and Chi-square (χ2 = 18.16, P < 0.05) tests revealed significant differences among groups. The ARI score of 3 (i.e., All adhesives left on the tooth) to be the most prevalent in Transbond XT (40%), followed by Rely-a-Bond (30%), Transbond Plus with Transbond XT (15%), and Xeno V with Xeno Ortho (10%). Under SEM, enamel surfaces after debonding of the brackets appeared porous when an acid-etching process was performed on the surfaces of Rely-a-Bond and Transbond XT, whereas with self-etching primers enamel presented smooth and almost clean surfaces (Transbond Plus and Xeno V group). Conclusion: All adhesives yielded SBS values higher than the recommended bond strength (5.9-7–8 MPa), Seventh generation self-etching primer Xeno V with Xeno Ortho showed clinically acceptable SBS and the least amount of residual adhesive left on the enamel surface after debonding.

An ultrasonographic evaluation of masseter muscle thickness in different dentofacial patterns.

OBJECTIVES The aim of this study is to compare the masseter muscle thickness in different vertical dentofacial patterns and identify the possible sexual dimorphism and also to correlate masseter muscle thickness with craniofacial morphology using cephalometric parameters. MATERIALS AND METHODS The masseter muscle thickness was measured using ultrasonography in 60 subjects (30 females and 30 males). Standardized lateral and posteroanterior cephalograms were taken to determine the facial morphology. The subjects were divided into three vertical pattern groups (I, II, and III) according to their Jarabak ratio: hypodivergent ( n = 20), normodivergent (n = 20), and hyperdivergent (n = 20). The sample was further subdivided into males and female subgroups. RESULTS Masseter muscle thickness relaxed (MMTR) in hypodivergent group was 13.94 ± 1.51. Mean value of MMTR in normodivergent group was 12.53 ± 1.21 and the MMTR in hyperdivergent group was 11.13 ± 1.18. The mean value of masseter muscle thickness contracted (MMTC) in hypodivergent group was 15.46 ± 1.33. Mean value of MMTC in normodivergent group was 13.81 ± 1.38 and the mean value of MMTC in hyperdivergent group was 12.27 ± 1.26. MMTC showed a significant, negative correlation with mandibular plane angle and gonial angle. Posterior facial height, symphysis width, intermolar width of maxillary first molars, maxillary width, and facial width (bizygomatic width) showed significant ( P < 0.05 or P < 0.01) positive correlation. CONCLUSION The masseter muscle thickness varied among the three vertical dentofacial patterns and sexual dimorphism also existed except in the hyperdivergent group. Masseter muscle thickness was found to be negatively correlated to vertical facial pattern and positively associated with transverse craniofacial morphology.

Cephalometric evaluation of hyoid bone position and pharyngeal spaces following treatment with Twin block appliance.

Objective: To evaluate the position of hyoid bone in the subjects treated with Twin block appliance. Materials and Methods: The sample consisted of 40 Angles Class II division 1 subjects treated with Twin block appliance. Lateral radiographs were taken before and after treatment. According to Schudys facial divergence angle (SN-MP), the subjects were classified in to three groups: group I (hypodivergent, SN-MP: <31° (27°-30°), n=15), group II (normodivergent, SN-MP: 31°-34°, n=15), and group III (hyperdivergent, SN-MP: >34° (35°−38°), n=10). Lateral cephalograms were traced and analyzed manually. After measurements of variables, Students t-test and one-way analysis of variance (ANOVA) were performed. Results: Post treatment with Twin block therapy, hyoid bone shifted significantly (P<0.01) forward in horizontal dimension in all three groups, although it was highest in group III. However, there was no significant difference amongst the groups. In vertical dimension, hyoid bone shifted in upward direction in all three groups; however, the shift was significant (P<0.01) only in group I and there was a significant difference between group I and rest of the two groups. Width of upper airway significantly (P<0.01) increased and ANB angle significantly (P<0.001) decreased in all three groups with forward movement of mandible. Conclusions: After treatment with Twin block appliance, significant changes occurred in horizontal dimension (anterior displacement), which resulted in significant increase in width of upper pharynx in all three groups.

Soft-tissue characteristics of Class-II Division-1 malocclusion in North Indian adult population: A cephalometric study

Background: Facial harmony in orthodontics is determined by the morphologic relationships and proportions of the nose, lips and chin. For the correction of all malocclusions, the facial outlines should be regarded as an important guide in developing a proper treatment plan. Aims and Objectives: (1) The primary aim is to evaluate and compare the soft tissue pattern associated with Angle′s Class I normal occlusion and Angle′s Class-II Division-1 malocclusion in North Indian adult population. (2) The secondary is to access sexual dimorphism for the soft-tissue characteristics. Materials and Methods: Lateral cephalograms of 80 orthodontically untreated adult subjects, 40 were having normal occlusion with good facial profile (Group-A: 20 males-mean age 22.89 years and 20 females-mean age 21.27 years) and 40 subjects with Angle′s Class-II Division-1 malocclusion (Group-B: 20 males-mean age 20.25 years and 20 females-mean age 19.67 years) were analyzed. Methodology: Lateral cephalograms of the subjects were taken in natural head position and were traced manually. 16 linear and 6 angular soft-tissue parameters were measured which were derived from the Steiner, Ricketts, Burstone and Holdaway soft-tissue analyses. All the values were compared using Student′s t-test with a level of significance at P < 0.05. Results: Group-B males had decreased lower lip length, lower face height, nasomental angle (P < 0.001) and lip length ratio (P < 0.01) whereas increased interlabial gap, upper lip to Sn-Pg′, total facial contour angle, maxillomandibular contour angle (P < 0.001), lower lip to Sn-Pg′ angle (P < 0.01) when compared to Group-A males. There was an apparent sexual dimorphism was found in soft-tissue pattern of both the groups. Conclusions: Class-II Division-1 malocclusion have more convex soft-tissue profile, reduced nose length, Shorter procumbent lips and flatter chins when compared to Angle′s Class I malocclusion.

Alignment of palatally impacted canine with open window technique and modified K-9 spring

The patient was an 18-year-old female who had an Angle Class I malocclusion with a left palatally impacted maxillary canine. The orthodontic treatment of a palatally impacted canine is aimed at bringing the tooth into its correct position in the dental arch without causing any periodontal damage. To achieve this goal, a variety of surgical and orthodontic techniques have been proposed in relation to the position of the impacted tooth and there are various treatment methods used for traction. The duration of the traction was 3 months and alignment duration was 12 months the total treatment time was 15 months. In the following case, we presented that maxillary palatally impacted canine was brought into the arch with open window method for canine exposure and modified K-9 spring for traction, that is simple spring for orthodontic traction of the palatally impacted canines.

Cephalometric norms for the upper airway in a healthy North Indian population

Objective: The aim was to obtain normative data for cephalometric measurements of the upper airway in the North Indian population. Design: Observational study. Setting: University department and teaching hospital out-patient clinic. Subjects and Methods: A total of 180 healthy patients were included out of which 90 were males (age range, 8-16 years), and 90 were females (age range, 8-16 years), with normal skeletal facial profile, no history of snoring, sleep apnea, upper airway disease, tonsillectomy or adenoidectomy, obesity, or pathology in the pharynx. Twenty cephalometric airway measurements, including size of the tongue, soft palate, nasopharynx, oropharynx, hypopharynx, and relative position of the hyoid bone and valleculae were obtained. Landmarks on cephalometric radiographs were digitized and measurements were made using a specially designed computer program. Error analysis of measurements was performed and comparison of measurements according to sex was made. Results: Significant sex dimorphism was seen for the majority of measurements, with the exception of minimal depth of the airway, oropharyngeal depth of the airway, and the soft palate angle with the hard palate. Conclusion: A minimum sagittal dimension of the upper airway was evident despite differences in measurements between sexes. Findings from this study should be a useful reference for the assessment of sleep apnea in the North Indian population.

Dental consequences of mouth breathing in the pediatric age group

Background: The presence of mouth breathing (MB) in pediatric patients is a relatively common fact and may result in a series of changes characteristic of occlusal features. In the presence of unbalanced muscular activity, dental inter-arch relationship is the important parameter to understand the patients occlusion. Therefore, it is important to assess the occurrence of occlusal disorders among MB children. Aim: The present study is undertaken to verify the dental occlusal characteristics with extent of MB and nasal breathing in a pediatric patient. Materials and Methods: A cross-sectional study was performed to assess the association of changed mode of respiration with occlusal variables from dental cast. Ninety-two subjects, of whom 40 were mouth breathers and 52 were nasal breathers, of 7-11 years of age were submitted to clinical examination and dental cast analysis. Results: Mouth breathers demonstrated considerable increase in palatal height and increased overjet, and statistically significant narrowing of the upper arch at the level of the molar. Conclusion: Changed mode of respiration during critical growth periods in children has a higher tendency for increased palatal height and overjet, reduced overbite and maxillary intermolar width.

Correction of minor crowding using thermoformed appliance with selective trimming

Todays patients demand correction of malocclusion without any compromise in esthetics. Thermoformed appliances are good alternative to treat such cases. In this article, we will discuss the correction of minor crowding using thermoformed appliance with selective trimming.

Management of severe skeletal Class III malocclusion with bimaxillary orthognathic surgery

Orthognathic surgery in conjunction with fixed orthodontics is a common indication for interdisciplinary management of severe skeletal Class III malocclusion. A thorough analysis of pretreatment investigations and development of a surgical visual treatment objective is essential to plan the type of surgical technique required. Bimaxillary orthognathic surgery is the most common type of surgical procedure for severe skeletal discrepancies. The present case report is a combined ortho-surgical team management of a skeletally Class III patient. The severity of the case required bilateral upper first premolar extraction for dentoalveolar decompensation and simultaneous “Two-jaw surgery” with maxillary advancement of 4 mm and mandibular setback of 7 mm. Postsurgery, a pleasing good facial profile was achieved with Class II molar relation and positive overjet.