Occlusal outcome in patients undergoing orthognathic surgery with internal fixation.

Fifty consecutive patients undergoing orthognathic surgery with internal fixation (IF) were studied retrospectively with a weighted Peer Assessment Rating (PAR) Index to assess occlusal outcome at the end of all active treatment, and compared with 50 patients who had undergone treatment for malocclusion by orthodontic means alone. In the surgically treated patients, the mean percentage reduction in the weighted PAR Index was 83% and 31 out of 38 patients (82%) were 'greatly improved'. This implies a high standard of treatment in terms of the occlusal outcome. There was no difference in the proportion of patients having a final weighted PAR Index of less than 10 and no significant difference in the final weighted PAR Index between the two groups. This suggests that the occlusal outcome is no different whether patients undergo orthognathic surgery or orthodontic treatment alone, and that excellent occlusal results can be achieved in patients undergoing orthognathic surgery with internal fixation.

Management of palatally impacted canines: the findings of a collaborative study.

The impacted palatal canine requires a combination of both surgical and orthodontic management. Two types of approach are commonly used: simple exposure, or exposure with bracketing at the time of surgery. In this study 104 consecutively treated patients with palatally impacted canines were examined at two centres, one at which the ectopic tooth was surgically exposed alone and the other where an orthodontic bracket was bonded to facilitate early traction, and the flap replaced. The aim was to compare the outcome and complication rate for each type of procedure. In 30.7 per cent of all cases exposed and bracketed a second surgical intervention was required, compared with 15.3 per cent in the simple exposure group. Bracketing, though effective, is a more costly and time-consuming procedure, and it is suggested that simple exposure provides an equally efficient and predictable method of managing the palatally impacted canine with obvious clinical and financial benefits. The long-term periodontal status of the teeth which have been exposed in these two ways, however, needs further investigation.

The clinical use of Activa self-ligating brackets.

The advantages and disadvantages of Activa self-ligating brackets ("A" Company, San Diego, Calif.) are discussed in the light of extensive clinical experience and the currently available data concerning frictional forces between arch wires and these brackets. Detailed practical recommendations are made concerning the problems that are encountered. The principal clinical advantages arise from the unusual combination of very low friction and excellent control of arch wire engagement. The potential benefits are the rapid alignment of very irregular teeth, lower anchorage requirements, and facilitation of sliding mechanics. Several problems arise from the unfamiliarity of a bracket without tie-wings, but the most significant drawback is the bond failure rate which is currently higher than with conventional brackets from the same manufacturer.

Labial sensory function following sagittal split osteotomy.

A retrospective assessment of labial sensory function following sagittal split osteotomy was undertaken by a combination of record analysis, postal questionnaire and objective sensory testing. Case records for 90 sides operated upon by a single consultant surgeon between 1979 and 1992 identified a prevalence of persisting sensory changed at 2 years of 6.7%. A higher incidence of sensory change was seen in patients treated with intermaxillary fixation/upper border wires than those managed with buccal monocortical miniplates. Postal questionnaire returns for 67 consultant operated sides identified a higher incidence of sensory change than recorded in the notes. 5.9% had long term persisting anaesthesia. Another 28% had more variable subtle sensory impairment. A similar relation to method of fixation was seen. An association between duration of temporary sensory change and magnitude of forward mandibular advance was noted. Objective sensory testing validated the subjectively reported sensory status but also identified many patients self-assessed as normal had some undetected sensory impairment. Possible mechanisms for the above findings and implications for clinical practice are presented.

The Consultant Orthodontists Group survey of hospital waiting lists and treated cases.

A questionnaire sent to all U.K. hospital orthodontic consultants resulted in an 88 per cent response rate. The average waiting time for initial consultation was 31.6 weeks for routine cases and 3.6 weeks for urgent cases. The average waiting time for out patient treatment was 68.7 weeks for routine cases and 7.5 weeks for urgent cases. Nearly 33 per cent of hospitals used the Dental Health Component of the Index of Orthodontic Treatment need (IOTN) as a guide to placing patients on waiting lists. 'Urgency' and 'Complexity' were used more frequently than indices. Sixty-nine per cent of hospitals exclude some categories of malocclusion from treatment in their departments. A prospective survey reported on 2480 completed treatments over a six week period and there was an average discontinuation rate of 9.2 per cent of all cases finished during the period. Comparison of the completed and discontinued groups revealed few significant treatment-related factors. There was some evidence that the more senior and experienced the operator, the less the rate of discontinuation. A greater rate of discontinuation was seen in removable appliance cases when compared with fixed appliance cases.

A comparison of the forces required to produce tooth movement ex vivo through three types of pre-adjusted brackets when subjected to determined tip or torque values.

Friction in fixed appliance systems has received considerable attention in recent literature, although that attributable to varying second order (tip) and third order (torque) adjustments in either the bracket or the archwire has not been fully investigated. The ex vivo study of 0.022 x 0.028-inch slot Minitwin, Activa, and Standard Straight Wire brackets investigates friction when known values of tip or torque were applied to 0.018 x 0.025-inch stainless steel wires. The resistance to sliding of the wire through the ligated brackets was measured on a vertically-mounted Instron testing machine. The results showed that the self-ligating Activa brackets consistently produced less friction than the other conventionally tied brackets. Minitwin brackets were slightly more resistant to movement than the Standard brackets during torquing, but the converse was found when tip was applied. Increasing tip and torque (ranges tested 0-6 degrees and 0-25 degrees, respectively) produced almost linear increases in friction for all brackets, although increasing tip had the more profound effect on friction, particularly in Activa brackets.

A comparison of the forces required to produce tooth movement in vitro using two self-ligating brackets and a pre-adjusted bracket employing two types of ligation.

Friction in fixed appliance systems has received considerable attention in the recent literature, although that attributable to the type of ligation used has not been fully investigated. This in vitro study of 0.022 x 0.028 inch slot Minitwin, Activa ('A' Company, San Diego, California, USA), and SPEED brackets (Strite Industries Ltd., Cambridge, Ontario, Canada), investigates friction in two forms of self-ligating brackets and in two methods of ligating Minitwin straight wire brackets with polyurethane elastomeric ligatures. The resistance to sliding of rectangular archwires through the ligated brackets was measured on a vertically mounted Instron testing machine. The stainless steel archwires used were straight lengths of 0.016" x 0.022", 0.017" x 0.025", 0.018" x 0.025", and 0.019" x 0.025" Nubryte Gold (GAC International Inc., Central Islip, New York, USA). The results showed a significant reduction (P < 0.01) in frictional resistance in the Activa brackets compared with SPEED brackets by a factor of approximately 15. When the SPEED brackets were compared to Minitwin brackets, the reduction in friction was by 50-70 per cent (P < 0.01). The placing of 'figure-of-eight' elastomeric ties increased friction by a factor of 70-220 per cent compared to conventional elastomeric ties (P < 0.01) except for 0.016" x 0.022" archwires. The results indicate that self-ligating brackets require less force to produce tooth movement because they apply less frictional contact to the archwire than conventionally tied siamese brackets.

Psychological aspects of fibromyalgia compared with chronic and nonchronic pain.

The description of psychological aspects of fibromyalgia are similar to those of other patients with chronic pain. Three groups, a chronic pain group (n = 99), a nonchronic pain group (n = 34) and a fibromyalgia group (n = 36) were compared, using a standardized interview and psychological questionnaires (SCL-90R, IBQ and CIPI). It appeared that the chronic pain group and the nonchronic pain group could be easily distinguished from each other with these variables. The scores of the fibromyalgia group and the chronic pain group were very similar. This leads to the conclusion that many psychological aspects of fibromyalgia can be considered as psychological aspects of chronic pain.

Computerized prediction of the results of orthognathic surgery.

Methods of visually and numerically predicting the results of orthognathic treatment are reviewed. The use of a computer program written by the authors and employing computer graphics for orthognathic prediction is described and illustrated. Suggested advantages and disadvantages of such a method are discussed.

Digital image processing of cephalometric radiographs: a preliminary report.

The principles of image capture, image storage and image processing in digital radiology are described. The enhancement of radiographic images using digital image processing techniques and its application to cephalometry is discussed. The results of a pilot study which compared some common cephalometric measurements made from manual point identification with those made by direct digitization of digital radiographic images from video monitors are presented. Although in an early stage of development, the results from the image processing system were comparable with those obtained by traditional methods.

On-line digitizing: useful mathematical techniques.

A mathematical and computational approach to some of the common problems found in writing digitizing programs for cephalometric analysis is described. The paper is aimed at those with access to a microcomputer and digitizer, some knowledge of the BASIC computer language and simple mathematics but little experience of writing digitizing programs.