Stress and displacement patterns in the craniofacial skeleton with rapid maxillary expansion-a finite element method study.

BACKGROUND: Rapid maxillary expansion (RME), indicated in the treatment of maxillary deficiency directs high forces to maxillary basal bone and to other adjacent skeletal bones. The aim of this study is to (i) evaluate stress distribution along craniofacial sutures and (ii) study the displacement of various craniofacial structures with rapid maxillary expansion therapy by using a Finite Element model. METHODS: An analytical model was developed from a dried human skull of a 12 year old male. CT scan images of the skull were taken in axial direction parallel to the F-H plane at 1 mm interval, processed using Mimics software, required portion of the skull was exported into stereo-lithography model. ANSYS software was used to solve the mathematical equation. Contour plots of the displacement and stresses were obtained from the results of the analysis performed. RESULTS: At Node 47005, maximum X-displacement was 5.073 mm corresponding to the incisal edge of the upper central incisor. At Node 3971, maximum negative Y-displacement was -0.86 mm which corresponds to the anterior zygomatic arch, indicating posterior movement of craniofacial complex. At Node 32324, maximum negative Z-displacement was -0.92 mm representing the anterior and deepest convex portion of the nasal septum; indicating downward displacement of structures medial to the area of force application. CONCLUSIONS: Pyramidal displacement of maxilla was evident. Apex of pyramid faced the nasal bone and base was located on the oral side. Posterosuperior part of nasal cavity moved minimally in lateral direction and width of nasal cavity at the floor of the nose increased, there was downward and forward movement of maxilla with a tendency toward posterior rotation. Maximum von Mises stresses were found along midpalatal, pterygomaxillary, nasomaxillary and frontomaxillary sutures.

Role of Orthodontics in Forensic Odontology- A Social Responsibility.

Orthodontics like any other specialty has much to offer law enforcement in the detection and solution of crime or in civil proceedings. Forensic odontology often requires an interdisciplinary approach towards dentistry for the purpose of proper diagnosis of cases. In cases where the forensic odontologist has to establish a person's identity, an orthodontist can be of great help at times. Teeth, with their anatomic/physiologic variations and therapy such as orthodontic treatment, restorations and prosthesis may record information that remains throughout life and beyond. The teeth may also be used as weapons for defense or offense and as such may leave information about the identity of the biter at the time of crime. Forensic odontology also plays an important role in the recognition of crime and abuse among people of all ages. Orthodontists like all other dental professionals can play a major role by maintaining proper dental records and thus providing important or vital information or clues to the legal authorities in order to help them in their search.

Orthodontic-periodontics interdisciplinary approach.

In this present era, when a significant number of patients seeking orthodontic treatment are adults, importance of multidisciplinary treatment approach cannot be overemphasized. Higher susceptibility of plaque accumulation in patients undergoing orthodontic treatment makes involvement of periodontist almost unavoidable. Also, orthodontic treatment frequently results in undesirable periodontal changes which require immediate attention. More recently, orthodontics has been used as an adjunct to periodontics to increase connective tissue support and alveolar bone height. The purpose of this article is to review the adverse effects of orthodontic treatment on the periodontal tissues and to discuss the mutually beneficial relationship shared between the two specialties.