Transverse displacement of the proximal segment after bilateral sagittal osteotomy: a comparison of lag screw fixation versus miniplates with monocortical screw technique.

PURPOSE: The purpose of the present study was to compare lag screw fixation versus miniplates with monocortical screw technique with respect to the amount of transverse displacement of the proximal segment after bilateral sagittal osteotomy (BSO) for mandibular advancement surgery. PATIENTS AND METHODS: We conducted a multicenter, retrospective investigation of 82 patients who underwent a mandibular advancement with BSO and rigid internal fixation. Forty-five patients from Denmark and Sweden, the miniplate fixation group, received a rigid fixation consisting of miniplates with monocortical screws. Thirty-seven patients from the Mayo Clinic, the lag screw fixation group, received a rigid fixation with lag screw fixation of the mandible. The transverse displacement and angulation of the proximal segments were measured on posterior-anterior cephalometric radiographs, using the best-fit method. RESULTS: After BSO, 44 of 45 patients in the miniplate fixation group showed an increased transverse intergonion distance with a mean of 5.0 mm and an increase transverse interramus width with a mean of 2.4 mm. Thirty-six of 37 patients in the lag screw fixation group had an increased intergonial width with a mean of 5.6 mm, and 35 of 37 patients showed an increased transverse interramus width with a mean of 3.3 mm. t tests showed that there were no significant differences between the 2 groups with respect to these 2 variables. CONCLUSIONS: Our results indicate that transverse displacements of the proximal segments occur after BSO surgery with both miniplate or lag screw fixation technique. Attention and future studies should focus on possible complications that transverse displacement of the proximal segment may cause.

Kinematic study of the mandible using an electromagnetic tracking device and custom dental appliance: introducing a new technique.

The purpose of this study is to introduce a new technique for recording the kinematics of the temporomandibular joint and incisors, using an electromagnetic tracking device and custom dental appliance. Five normal subjects took part in this kinematic study (4 females, 1 male, mean age of 34.8 years). Subjects' mandibular motion during maximal opening tasks were recorded on two different days and linear distance (LD) (i.e., the LD between the start and end position) and curvilinear path (CP) (i.e., the curvilinear distance along the curve between the start and end position) were calculated for the lower incisor landmark and both condyles in the sagittal plane (in mm). In the present study, the range of incisal movements (LD: 34.9 to 54.3 mm, CP: 36.5 to 60.3 mm) and that of condylar movements (LD: 7.5 to 25.3 mm, CP: 10.6 to 27.6 mm) in the sagittal plane during opening are in the normal range compared to the previous literature. The ability of subjects to reproduce the same motion between the two sessions was also calculated. Differences due to trial sessions and different repetitions within a session were negligible, indicating that the method can be used to assess changes between testing conditions in healthy subjects, and patients pre- and post-operatively.

Palatal displacement of canines and maxillary skeletal width.

INTRODUCTION: The purpose of this study was to determine whether a clinically significant association exists between maxillary skeletal width and palatal canine impaction, also known as palatally displaced canine (PDC). METHODS: Seventy-nine patients with PDC were matched for age, sex, and malocclusion to 79 controls. Maxillary and mandibular skeletal widths and nasal cavity widths were measured on posteroanterior cephalograms; maxillary and mandibular intermolar widths were measured on dental casts; and maxillary interalveolar arch widths at 3 levels (canine, premolar, and first molar) were measured on occlusograms. RESULTS: Only maxillary alveolar arch width at the canine level was significantly different between the 2 groups. However, further analysis showed that the presence of erupted deciduous or permanent canines, rather than their absence in the canine area (whether due to extraction, exfoliation, impaction, or not yet having erupted), was strongly associated with maxillary intercanine alveolar arch width. CONCLUSIONS: The additional finding in this study that the eruptive status of canines significantly affects maxillary alveolar arch width in this area suggests that maxillary intercanine alveolar arch width as measured in this or other studies is not a good predictor of PDC.

Interexaminer reliability of two cephalometric methods to determine proximal segment position after bilateral sagittal split ramus osteotomy.

The objective of this study was to evaluate the interexaminer reliability of two cephalometric methods for determining positional change of the proximal segment after a bilateral sagittal split ramus osteotomy (BSSRO) for mandibular advancement. The records of 25 patients were used in a double-blind trial. Two nontrained investigators (having read the articles describing the two cephalometric methods, but with no other special training) independently traced posterior-anterior (PA) and lateral cephalometric radiographs taken at three time intervals: (T1) before surgery, (T2) immediately after surgery, and (T3) after orthodontic treatment was completed. The level of agreement between the two investigators (interexaminer reliability) on all 25 patients was estimated by calculating the intraclass correlation coefficient (ICC). The ICC was found to have a high value, indicating "substantial" to "almost perfect agreement" between the two examiners. Thus the results validate the use of these two methods to determine proximal segment positional changes in the frontal and sagittal planes of space after a BSSRO.

Malocclusion associated with osteocartilaginous loose bodies of the temporomandibular joint.

BACKGROUND: The authors review the literature regarding osteocartilaginous loose bodies (that is, secondary synovial chondrometaplasia or secondary synovial chondromatosis) in the temporomandibular joint (TMJ), present a case report and stress the importance of early diagnosis. CASE DESCRIPTION: A 57-year-old woman was referred to an orthodontist with a chief complaint of bite changes that took place over several years as the patient intermittently experienced TMJ problems. The authors noted radiopacities around the right TMJ space on a panoramic radiograph. They referred the patient to an oral and maxillofacial surgeon for treatment. CLINICAL IMPLICATIONS: Asymmetrical occlusal changes in a nongrowing adult with progressive shifts from Class I to Class III malocclusion unilaterally may indicate a space-occupying lesion in the TMJ space on the affected side.

Maxillary impacted canine with congenitally absent premolars.

Multiple treatment options are available to patients who have impacted canines in addition to congenitally absent premolars. Management options for impacted maxillary canines can include (1) continued observation, (2) extraction of the primary canine to aid spontaneous eruption, (3) uncovering and bonding of the impacted tooth and its eruption using orthodontic traction, (4) autotransplantation, and (5) extraction followed by prosthetic replacement. The options for the treatment of missing premolars can include the following: (1) maintaining the primary molars, (2) spontaneous space closure after early extraction of the primary molar, (3) autotransplantation, (4) prosthetic replacement, and (5) orthodontic space closure. In this case report, treatment of a patient with an impacted maxillary canine and agenesis of three second premolars will be presented.

Treatment of a patient with an impacted transmigrant mandibular canine and a palatally impacted maxillary canine.

Very few people have seen transmigrant mandibular canines and little has been presented in the literature about this rare phenomenon. In this case report, identification techniques and treatment options are presented along with the treatment results of a patient diagnosed with a transmigrant mandibular canine. This rare condition usually requires extraction of the involved tooth because orthodontic forces are seldom successful at erupting these teeth into their proper location. The treatment protocol for this patient involved a combination of orthodontic procedures, surgical extractions, gingivectomy and frenectomy, and implant replacement of the impacted transmigrant tooth. Through a collaborative effort of a team made up of an orthodontist, periodontist, prosthodontist, and oral surgeon, these techniques were used to achieve an excellent esthetic and functional outcome.

The effect of argon laser irradiation on demineralization resistance of human enamel adjacent to orthodontic brackets: an in vitro study.

Argon lasers, because of their significant timesavings over conventional curing lights, have been investigated for use in bonding orthodontic brackets. They are also being investigated for their ability to confer demineralization resistance on enamel, which is of great interest in orthodontics. A two-part in vitro study on 86 human posterior teeth was conducted to determine the effects of a five-second argon laser exposure on shear bond strength and to evaluate the effects of a five- and 10-second argon laser exposure (250 mW) on demineralization of enamel surrounding orthodontic brackets after exposure to an artificial caries bath. Brackets cured with the argon laser for five seconds yielded mean bond strengths similar to those attained with a 40-second conventional light-cured control (n = 13 per group, 20.4 vs 17.8 MPa). Brackets cured with the argon laser for 10 seconds resulted in significantly lower mean lesion depth when compared with a visible light control (n = 20 per group, 107.8 vs 137.2 microm, P = .038). There were no statistically significant differences in lesion depth between the five-second argon laser and the visible light control groups. Overall, there was a 15% and 22% reduction in lesion depths for the five- and 10-second group, respectively. Poor correlations were found between the clinical appearance of decalcifications and their lesion depth. Argon lasers used for bonding orthodontic brackets would save a significant amount of chair time while possibly conferring demineralization resistance upon the enamel.

Skeletal and dental contributions to posterior crossbites.

The objective of this retrospective study was to compare skeletal and dental arch morphology of children with posterior crossbites with a control group of children without posterior crossbites. The study included 93 patients with a posterior crossbite (33 boys and 60 girls) and 97 patients without a posterior crossbite (50 boys and 47 girls). Skeletal and dental characteristics between the two groups were compared using measurements of dental casts, and lateral and posteroanterior cephalograms. Univariate analyses revealed that seven characteristics were significantly different between the crossbite and non-crossbite groups: mandibular plane angle, lower face height, skeletal maxillary to mandibular width ratio, maxillary intermolar width, mandibular intermolar width, maxillary to mandibular intermolar width ratio, and mandibular unit length. Using maxillary to madibular intermolar width ratio as the outcome measure, a stepwise variable selection technique, analyzed all 190 patients and found only two variables significantly associated with this measure: skeletal maxillary to mandibular width ratio and lower face height. The coefficient of multiple determination for this model was only 13%, indicating that these two variables accounted for only a small portion in the variation of the ratio between the maxillary and mandibular intermolar widths.

Transverse displacement of the proximal segment after bilateral sagittal split osteotomy advancement and its effect on relapse.

PURPOSE: To evaluate the transverse displacement of the proximal segment and its association with horizontal relapse post-treatment. METHODS: Retrospective study of 25 patients (10 males, 15 females) who underwent bilateral sagittal split osteotomy (BSSO) advancement and Le Fort I osteotomy with rigid internal fixation (RIF) using bicortical lag screws. Posteroanterior and lateral cephalograms obtained preoperatively (T1), early postoperatively (T2), and after orthodontic treatment completion (T3) were used to assess: the angulation of each proximal segment relative to the upper orbital margin line and obtain the sum of both angles (total angle), mandibular intergonial width (IGW), mandibular length (Ar-B), B point position, and condylion position. Paired t tests were used to determine statistically significant (P < .05) changes within the variables between various time points (T2-T1; T3-T2; T3-T1). Correlations between variables were estimated by calculating Pearson's correlation coefficients. RESULTS: T2-T1 findings: all 25 patients showed an increase in IGW with a mean of 6.5 +/- 2.5 mm and the angulations of the proximal segments increased 3.2 +/- 2.6 degrees (total angle change). Ar-B increased 3.8 +/- 3.4 mm. B point moved anteriorly 4.8 +/- 2.9 mm. T3-T2 findings: IGW decreased 1.8 +/- 1.5 mm; angulation of the right and left proximal segments decreased 1.2 +/- 2.8 degrees (total angle change). Condylion moved superiorly 1.5 +/- 2.0. CONCLUSIONS: Statistically significant changes occurred in transverse width and angulation of proximal segments of patients who underwent BSSO advancement with Le Fort I osteotomy. No clinically significant associations were found between transverse displacement of the proximal segments and horizontal relapse.

Kinematic study of the temporomandibular joint in normal subjects and patients following unilateral temporomandibular joint arthrotomy with metal fossa-eminence partial joint replacement.

PURPOSE: The primary purpose of this study is to quantify the kinematics of the temporomandibular joint (TMJ) in patients following unilateral TMJ arthrotomy with metal fossa-eminence partial joint replacement and compare them with TMJ kinematics of healthy individuals. MATERIALS AND METHODS: Fourteen healthy volunteers and 13 female surgical patients (minimum 4 years postoperative) participated in this study. An electromagnetic tracking device was used to record the kinematics of the mandible relative to temporal bone during opening-closing, protrusive, and lateral movements. The mean linear distance (LD) traveled by condyles was compared between operated and normal subjects. RESULTS: Patients responded with statistically significant improvement in pain and jaw function questions. Mean satisfaction with the surgical result was 25.7 on a scale of 1 to 30. The LD measured for condyles during all 4 movements showed similar measurements. However, operated and unoperated condyles showed statistically significant motion values during opening and protrusive motion from each other and from normal subjects. In addition, contralateral condyles during lateral motion showed statistically significant values in operated, unoperated, and normal condyles. CONCLUSION: The results of this study suggest that the surgical reconstruction of the TMJ with partial joint replacement provided highly significant clinical improvement. Moreover, condyle and incisor kinematics were preserved to a significant amount as compared with the normal group. The difference in kinematic measurements between the operated and unoperated condyle was significant and secondary to previous joint disease and previous surgical intervention. These results should be evaluated by prospective studies in pre- and postsurgical patients.

Dental team management for a patient with cleidocranial dysostosis.

Cleidocranial dysostosis is a rare autosomal condition that affects ossification. The dental abnormalities associated with it present a remarkable challenge in orthodontic treatment planning. Early diagnosis is extremely important to give the patient the best treatment options. Patients with cleidocranial dysostosis require a team approach with good communication and cooperation from the patient. Timing of the intervention is critical, and many surgeries might be required. The patient in this report was treated with a team effort that involved several dental specialties to achieve an optimal result.

Stability of the Le Fort I osteotomy with anterior internal fixation alone: a case series.

PURPOSE: The purpose of this case series was to evaluate the late postsurgical stability of the Le Fort I osteotomy with anterior internal fixation alone and no posterior zygomaticomaxillary buttress internal fixation. PATIENTS AND METHODS: Sixty patients with maxillary vertical hyperplasia and mandibular retrognathia underwent a 1-piece Le Fort I osteotomy of the maxilla with superior repositioning and advancement or setback. A bilateral sagittal split ramus osteotomy for mandibular advancement was also performed in 22 patients. Stabilization of each maxillary osteotomy was achieved using transosseous stainless steel wires and/or 3-hole titanium miniplates in the piriform aperture region bilaterally, with no zygomaticomaxillary buttress internal fixation. (Twelve of the 60 identified patients were available for a late postoperative radiographic evaluation.) Lateral cephalometric radiographs were taken preoperatively (T1), early postoperatively (T2), and late postoperatively (T3) to analyze skeletal movement. RESULTS: These 12 patients (5 male, 7 female) had a mean age of 24.5 years at surgery. Mean time from surgery to T2 was 41.2 days; mean time from surgery to T3 was 14.8 months. One patient received anterior wire osteosynthesis fixation, while 11 patients received both anterior titanium miniplate internal skeletal fixation and anterior wire osteosynthesis fixation. Six patients underwent Le Fort I osteotomy with genioplasty, 1 patient underwent Le Fort I osteotomy with bilateral sagittal split ramus osteotomy, and 5 patients underwent Le Fort I osteotomy with bilateral sagittal split ramus osteotomy and genioplasty. These 12 patients all underwent maxillary superior repositioning with either advancement (11 patients) or setback (1 patient). Statistically significant surgical (T2-T1) changes were found in all variables measured. In late postsurgical measurements (T3-T2), all landmarks in the horizontal and vertical plane showed statistically significant skeletal stability. CONCLUSION: This case series suggests that anterior internal fixation alone in cases of 1-piece Le Fort I maxillary superior repositioning with advancement has good late postoperative skeletal stability.

Effect of mandibular setback via bilateral sagittal split ramus osteotomy on transverse displacement of the proximal segment.

PURPOSE: The purpose of this study was to evaluate if a correlation exists between: a) transverse changes in the proximal segments because of mandibular setback surgery and b) postsurgical horizontal relapse of the mandible. PATIENTS AND METHODS: A total of 42 patients underwent bilateral sagittal split ramus osteotomy setback with rigid fixation and Le Fort I osteotomy performed by 1 surgeon between 1986 and 2000. The radiographic material for this study consisted of posteroanterior and lateral cephalometric radiographs for each patient taken preoperatively (T1), early postoperatively (T2), and late postoperatively (T3). Twenty-four of the 42 identified patients had T1, T2, and T3 radiographs, while the remainder of the patients had only T1 and T2 radiographs available. The posteroanterior radiographs were used to evaluate the angulation of the proximal segment and the intergonial width. RESULTS: Statistically significant increases in intergonial width and proximal segment angulation occurred from T1 to T2. In fact, all 42 patients had an increased intergonial width from T1 and T2. From T2 to T3, most patients underwent some relapse in their transverse dimension changes (21 of 24 patients had a decrease in their intergonial width). Overall, the intergonial width and the proximal segment angulations were significantly increased from T1 to T3. However, there was no significant correlation between the amount of transverse displacement of the proximal segment and horizontal postsurgical relapse of the mandible. CONCLUSION: The results show that statistically significant changes in the transverse width and angulation between proximal segments occur in patients undergoing bilateral sagittal split ramus osteotomy for mandibular setback with rigid fixation. However, the magnitude of the changes was small, and it is still uncertain as to whether these changes are of any clinical significance.

Congenitally missing mandibular second premolar: treatment outcome with orthodontic space closure.

Orthodontic treatment for patients with congenitally missing mandibular second premolars can be challenging. Treatment options include keeping the deciduous second molar, extracting the molars and allowing the space to close spontaneously, autotransplantation, prosthetic replacement, and orthodontic space closure. Space closure with orthodontic appliances is demonstrated in this case report.

Intraoral maxillary quadrangular Le Fort II osteotomy: a long-term follow-up study.

PURPOSE: This study evaluated the clinical outcome and skeletal stability of the intraoral maxillary quadrangular Le Fort II osteotomy (IQLO) with wire or rigid internal fixation following horizontal maxillary advancement. PATIENTS AND METHODS: All 21 patients who had undergone the IQLO were analyzed for operation time, blood loss, length of hospitalization, intraoperative and postoperative complications, and radiographic abnormalities. Lateral cephalometric radiographs were taken preoperatively (T1), postoperatively (T2) and late postoperatively (T3) to analyze skeletal movement. Two maxillary landmarks (posterior nasal spine [PNS] and A point) and 2 dental landmarks (the distobuccal cusp tip of the maxillary left second molar [2M] and the maxillary incisal tip [CI]) were used to determine horizontal and vertical changes for each time period. Student t test was used to evaluate early postoperative changes and late postoperative stability. In addition, 21 patients completed a questionnaire at the most recent follow-up visit regarding personal intentions, perceived outcome, and overall satisfaction. RESULTS: Twenty-one patients (9 females, 12 males) with an average age of 20.3 years diagnosed with horizontal maxillary-zygomatic deficiency underwent IQLO by 1 surgeon with an average follow-up of 6.3 years. Nine patients received mini-plate osseous segment fixation and 12 patients received wire osseous segment fixation. The mean time from surgery to the first postoperative radiograph (T2) was 4.4 weeks (range 1.0 to 6.7 weeks) and the mean time from surgery to the late postoperative radiograph (T3) was 6.2 years (range, 7.9 to 176.3 months). Statistical analysis of cephalometric landmarks revealed the following significant late postsurgical movements (T3-T2) for wire fixation: PNS moved 1.0 mm inferiorly (SD, 1.2), and 2M moved 1.5 mm inferiorly (SD, 2.2). The remaining cephalometric landmarks for rigid and wire fixation showed no statistically significant late postsurgical movement. Clinical outcome analysis revealed few complications, low surgical and postsurgical morbidity, and excellent patient satisfaction. CONCLUSION: The IQLO is a predictable procedure that exhibits long-term skeletal stability. Long-term retrospective review revealed low postsurgical morbidity and high patient satisfaction.

Transverse displacement of the proximal segment after bilateral sagittal osteotomy.

PURPOSE: The aim of the present investigation was to evaluate the transverse displacement of the proximal segment and ramus rotation after a bilateral sagittal osteotomy (BSO) with rigid internal fixation (RIF) using bicortical LAG screws. PATIENTS AND METHODS: We conducted a retrospective review of 37 patients (14 males and 23 females, age range of 14 to 55 years) who underwent a mandibular advancement with BSO and RIF. Posteroanterior and lateral cephalometric radiographs were obtained 1 to 8 weeks before and 1 to 4 weeks after surgery. The transverse displacement and angulation of the proximal segments after surgery were measured on posteroanterior radiographs, using the best-fit method. The amount of mandibular advancement was compared with the amount of transverse displacement of the proximal segments. RESULTS: In the 1 to 4-week postoperative period after a BSO, 36 of 37 subjects showed an increased transverse intergonion distance (5.6 mm) (P <.0001) and 35 of 37 patients showed an increased transverse interramus width (3.3 mm) (P <.0001). No correlation was found between mandibular advancement and transverse displacement of the proximal segment. CONCLUSIONS: The study results indicate that transverse displacements of the proximal segments occur with BSO and RIF. The clinical impact on temporomandibular joint symptomatology or surgical relapse with such displacement was not assessed in the study. Future studies that address these issues may help to determine whether there is an association between proximal segment displacement and surgical relapse, temporomandibular dysfunction, or both.