Stability of skeletal Class II correction with 2 surgical techniques: the sagittal split ramus osteotomy and the total mandibular subapical alveolar osteotomy.

Combined orthodontic and surgical treatment of severe Class II dentoskeletal deformities with the use of the bilateral sagittal split ramus osteotomy is a routine procedure in orthodontic practices. However, an alternative surgical technique, the total mandibular subapical alveolar osteotomy, could be used for the same purpose. The aim of this investigation was to compare the stability of the sagittal split ramus osteotomy with the total mandibular subapical alveolar osteotomy in the correction of dentoskeletal Class II malocclusions. Forty patients that exhibited Class II dentoskeletal relationships were included in the study. Twenty of these patients had mandibular advancement with the sagittal split ramus osteotomy; the remaining 20 patients had advancement of the whole lower alveolar segment with the total mandibular subapical alveolar osteotomy. The cephalograms studied were taken before the surgical procedure (T1 = 4 weeks before operation), immediately after the procedure (T2 = 10 days after surgery), and 1 year later (T3). The statistical analysis used to assess the results between and within the groups over the different time periods was the analysis of variance. The regression analysis was used to test the interdependence of soft tissue response to hard tissue movement. The results of this study show that both procedures are equally stable when correcting Class II malocclusions. This was proved by the stability of the correction of overjet, B point, and incisor-mandibular plane angle. There were no statistically significant differences between or within the groups in the position of these landmarks over time. There was a statistically significant change in the position of pogonion from T1 to T2 (P <.0028) between the groups, although at T3 this difference was not significant (P <.05). There were no significant changes in face height either within or between the groups over time. The hard/soft tissue interactions for the total mandibular subapical alveolar osteotomy were as follows: The lower lip advanced 60% to the incisor movement; soft tissue B' point responded with a 130% advancement in relation to the change in its hard tissue counterpart. Soft tissue pogonion advanced 90% in relation to the hard tissue landmark. The data suggest that the total mandibular alveolar osteotomy is the treatment of choice for the correction of severe dentoalveolar retrusive Class II malocclusion for which alteration of the mentolabial sulcus is desirable.

Stability of bilateral sagittal split ramus osteotomy: rigid fixation versus transosseous wiring.

Although many improvements have been made in orthodontic surgical procedures for mandibular retrognathism, relapse continues to occur. This study was designed to compare the stability of rigid and nonrigid fixation between 2 groups of patients who had undergone mandibular advancement surgery via sagittal split ramus osteotomy. Retrospective cephalometric measurements were made on 54 randomly selected orthognathic surgical patients. The patients, 7 males and 47 females, were divided into 2 groups: 28 patients stabilized by means of rigid fixation and 26 patients fixated with interosseous wires. The age of the patients ranged from 15.3 to 49.7 years. Lateral cephalograms were used to evaluate each patient at 3 distinct intervals: 7.0 +/- 2.0 days before surgery (T1), 34.4 +/- 15.0 days postsurgery (T2), and 458 +/- 202 days after sagittal split osteotomy (T3). Eighteen linear and angular measurements were recorded and differences between the 3 time periods were evaluated. Statistical analyses were performed to assess the differences in the 2 fixation types between and within each group at different time intervals. The following measurements showed statistically significant skeletal relapse over time, for the P value.0028: Co-Go, ANS-Xi-Pm, IMPA, overbite, and overjet. The remaining variables showed no statistically significant relapse. The only measurement that showed a statistically significant group difference between T1 and T2 was DC-Xi-Pm. Results of the study led to the following conclusions: there was statistically significant relapse in mandibular length, lower anterior face height, mandibular arc, lower incisor inclination, overbite, and overjet in each group, regardless of the type of fixation. The potential was greater for relapse in patients stabilized with transosseous wiring. Although multifactorial, relapse in overbite and overjet may be a combination of skeletal and dental changes. (Am J Orthod Dentofacial Orthop 2000;118:397-403).

Photographic analysis of facial changes associated with maxillary expansion.

Previous studies on the effects of surgical and rapid palatal expansion have been largely based on general skeletal and dental findings ascertained from radiographs and casts. The aim of this study was to measure and compare the soft tissue changes of the face during the expansion process and to determine the stability of any changes 1 year later. The sample consisted of 44 patients with unilateral or bilateral posterior crossbites. Twenty-four of the patients required a surgically assisted expansion procedure, and a second group of 20 patients were treated with orthopedic expansion. Ten measurements were made from standardized frontal facial photographic slides at 5 intervals of treatment: initial, bond appliance, stop expansion, debond appliance, and 1 year retention. Differences over time between the surgical and nonsurgical groups were analyzed by a 2 way multivariate analysis of variance (MANOVA) and post hoc t tests. Differences between initial and 1 year retention were found in the nasal widths (P <.001) of both surgical and nonsurgical groups. Other significant changes and trends were discussed.

Early treatment outcome assessed by the Peer Assessment Rating index.

In this study, the Peer Assessment Rating (PAR) index was used to objectively evaluate early treatment outcomes. Pretreatment and posttreatment casts of 103 consecutively treated patients were analyzed. The mean chronological, skeletal, and dental ages were 9. 82, 9.76, and 9.32 years, respectively. Calibrated examiners scored all models using the PAR ruler. PAR scores were weighed by means of a validation exercise. Cronbach alpha reliability analysis was used to establish the consistency of the subjective rating among 10 orthodontists of the severity of malocclusion. Pearson's correlation coefficient was used to assess the association among the orthodontists and the total PAR scores. Multiple regression analysis was used to determined the optimum weight of the PAR scores. Pretreatment and posttreatment differences were evaluated with t tests. The association between PAR scores and classification of malocclusions and treatment categories was assessed by means of multivariate analysis of variance (MANOVA). A reduction in the PAR index was observed for the mean raw and weighted scores, from 15.82 to 8.82 and from 5.28 to 3.73, respectively (P <.001). Twenty percent of the sample greatly improved the PAR index, by a 70% reduction.3 Forty-eight percent improved scores by at least a 30% reduction.4 The remaining 32% did not reduce scores by at least 30%. Subjects with both Class I and Class II malocclusions reduced their scores similarly. There was no statistically significant association between reduction of PAR scores and treatment modalities.

Stability of orthopedic and surgically assisted rapid palatal expansion over time.

At the present time no reports are available on the stability between orthopedic and surgically assisted rapid palatal expansion. This study was designed to examine and compare the dental and skeletal changes over time for both orthopedic maxillary expansion and surgically assisted palatal expansion. The study was divided into two groups. Group one was orthopedically expanded and consisted of 14 males and 10 females. The ages ranged from 6 years to 12 years with a mean of 8.5 years. Group two received surgically assisted rapid palatal expansion and consisted of 12 males and 16 females with ages ranging from 13 years to 35 years and a mean age of 19.25 years. All 52 subjects were white, from the same geographic area, and were treated by the same two operators. Dental models and posterior anterior cephalograms were obtained immediately before and after expansion, at removal of the expansion device, and 1 year after removal of the appliance. A repeated measures analysis of variance test was applied to assess changes over time between groups. The surgical and nonsurgical techniques displayed similar trends over time although the surgical group contained a greater quantity of expansion. Both the orthopedic and the surgical groups showed stable results.

Effects of protraction mechanics on the midface.

Forty patients with Class III maxillary deficiencies were each treated with a bonded maxillary palatal expansion appliance followed by protraction. Nineteen of the 40 patients were retained with a Frankel III appliance. This group was compared with 24 Class I patients treated solely with bonded expansion appliance mechanotherapy. To determine at which level protraction mechanics affects the maxilla, the Walker's analysis and other cephalometric measurements were used. The protraction group showed significant increases (p <.05) in the following measurements: ANB angle, Wits, A perpendicular to nasion and in sella to A point. Anterior molar movement, without changes in posterior nasal spine or upper incisor to SN, was evident (p <.05). Favorable change in the facial profile was noted. There were no changes in the angles between sella-nasion and its relationship with the Frankfurt, occlusal, palatal, and mandibular planes. Walker's analysis showed no change in the position of orbitale. The control group did not demonstrate any significant changes in the position of the maxillary complex as a result of expansion mechanics. The retention group maintained the position of the maxilla postprotraction. Facial contour was maintained and other profile related variables improved.

Surgical correction of skeletal Class III malocclusions using cranial base length (corrected and uncorrected) as a reference.

This study was an attempt to show how a variation in the anteroposterior position of nasion, or length of the anterior cranial base, when used as a reference line, affects the esthetic outcome of surgically repositioned bony bases. Five white female subjects exhibiting a short anterior cranial base and characterized by maxillary retrusion were included in this study. Lateral cephalograms and 35-mm photographs of each subject were digitized into a computer imaging system, and computer-simulated surgical procedures were performed. Soft tissue profiles were then generated to reflect the skeletal changes that took place. When three groups of respondents were asked to choose the most pleasing profile, the majority (65%) chose the maxillary (Le Fort I) surgical procedure, in which the cranial base was extended to a range of corrected "normals." These results indicate that when cephalometrics are used to formulate a diagnosis and treatment plan, the most esthetic result may be obtained if the landmarks that are important to the analysis, in this case, the anterior cranial base length, are normalized.

Assessment of condylar position following bilateral sagittal split ramus osteotomy with wire fixation or rigid fixation.

In this study, 53 patients who underwent a bilateral sagittal split ramus osteotomy to advance the mandible were examined radiographically to assess condylar position presurgically, postsurgically, and posttreatment. Subjects were separated into two groups, 29 patients who received wire fixation and 24 who received rigid internal fixation. Condylar position changes were measured on tracings of submentovertex and transcranial radiographs at the time periods mentioned. Differences in condylar position were evaluated in two defined time intervals--T1, presurgical to postsurgical, and T2, postsurgical to posttreatment. Right and left sides were evaluated independently. No correlation between amount of advancement and condylar position change was identified within or between the fixation groups at T1 and T2. No correlation between change in mandibular plane angle and change in condylar position was identified within or between the groups at T1 and T2. Statistically significant differences were identified between the fixation groups in the degree of condylar change measured on the tracings of both submentovertex and transcranial radiographs both right and left sides, at time T1. There was also a significant difference in the change in mandibular plane angle at T1 between the fixation groups. It appears from this study that use of rigid internal fixation following bilateral sagittal split ramus osteotomy results in a statistically significantly greater condylar displacement than does wire fixation. Further research is required to determine whether these changes in condylar position are clinically significant.

A comparative and correlational study of the cranial base in North American blacks.

The purpose of this investigation was to compare the cranial bases of blacks and whites in regard to length, angulation, and flexure, and to determine what proportion of the differences in facial measurements can be explained by the variability seen in the cranial base. Standardized cephalograms of 100 native-born North American black adults were traced, analyzed, and compared with white values. The measurements selected depicted dependency and independency from the cranial base. Mean differences between the races and the sexes were assessed with the Student's t test. Models of linear regression between the cranial base measurements and all other parameters were computed for both sexes and correlation coefficient values calculated. This study established that the length of the cranial base in North American blacks is significantly shorter from that of whites. A strong biologic relationship was demonstrated between the length of the cranial base of blacks and their denture bases, the palatal, and occlusal planes. The data suggest that most of the cephalometric differences between blacks and whites are not simply anatomic for measurements using sella nasion as their reference plane.

Orthodontic considerations to reduce postsurgical relapse.

Despite the advances in diagnostic and orthognathic surgical techniques, a certain amount of dental or skeletal relapse occurs in orthodontically and surgically treated cases. The interaction of orthodontic therapy with the anticipated surgical procedure must be carefully analyzed and all aspects of the dento-skeletal malocclusion considered if facial balance, good perioral function, and stability are to be achieved. The role of different elements as they relate to the orthodontic stability, such as dental (eg, leveling and extraction patterns), periodontal (eg, gingival graft), skeletal (eg, maxillary expansion and alveolar distortion), and muscular (eg, tongue size and posture) factors, as well as the roles of growth and the airway are discussed and illustrated.

Bilateral gemination with talon cusp: report of case.

The extraction of the geminated maxillary central incisors was selected as the preferred treatment in this case because of the impossibility of properly recontouring these teeth. Although the crowns could have been reshaped somewhat to conform to a more normal size and shape, the roots were so wide that approximation of the central and lateral incisor crowns would have been impaired. The use of normally shaped, large lateral incisors in place of abnormal central incisors gives a better occlusion and a more esthetic result at the end of the treatment.

Total mandibular alveolar osteotomy: an alternate choice to other surgical procedures.

Patients whose facial esthetics are not severely compromised but who need surgical intervention for the correction of a dentoskeletal problem can be treated by repositioning of the whole mandibular alveolar segment in the direction needed to allow for such correction. The challenge to achieve efficient and relatively stable results with the use of combined orthodontic and surgical methods has been met by the use of various surgical techniques. The lower total alveolar osteotomy is another viable surgical technique that could be considered when treatment is being planned in an orthognathic surgical case. Its indications, contraindications, advantages, and disadvantages are described, and cases are reported to exemplify problems that can be corrected with this approach.

Maxillary skeletal and dental change with Fränkel appliance therapy--an implant study.

An implant study using postero- anterior cephalometric radiographs to evaluate expansion effects of the Fränkel appliance. Significant alveolar and apical base expansion was found in the treatment group, with much smaller increases at the midpalatal suture. Molar tipping was insignificant.