Comparison of three-dimensional soft tissue changes according to the split pattern after sagittal split osteotomy in patients with skeletal class III malocclusion.

OBJECTIVES: This study aimed to analyse the changes in soft tissue and hard tissue stability associated with the split pattern, i.e. long split (LS) or short split (SS), after sagittal split osteotomy. MATERIALS AND METHODS: Patients who underwent sagittal split ramus osteotomy were classified into LS or SS groups according to postoperative computed tomography images. They were examined via lateral cephalography and three-dimensional (3D) optical scanning before surgery (T0) and 1 (T1), 3 (T2), and 12 (T3) months after surgery. Six standard angles (SNA, SNB, ANB, FMA, FMIA, and IMPA) were used as measures of hard tissue change. The two sets of 3D data were superimposed, and the volumetric differences were calculated as the soft tissue change. The areas evaluated were delimited by 10 × 20-mm rectangles in the frontal aspect and a 25 × 25-mm square in the lateral aspect. RESULTS: A total of 42 sides (26 patients) were analysed, including 20 (16 patients) in the SS group and 22 (16 patients) in the LS group. We found no significant differences in cephalographic angle or soft tissue changes in the frontal aspect between the SS and LS groups. We found significant differences in the subauricular region from T0-T1 (p = 0.02), T0-T2 (p = 0.03), and T0-T3 (p = 0.037) in terms of soft tissue changes in the lateral aspect. The volume increase associated with posterior mandibular movement was greater in the LS group. CONCLUSIONS: We found that LS patients with mandibular prognathism exhibited increased subauricular volumes following mandibular setback. CLINICAL RELEVANCE: It is essential to predict the postoperative facial profile before surgery. The split pattern after sagittal split osteotomy affects the postoperative profile of patients with mandibular prognathism.

Radiologic Risk Factors for Persistent Mandibular Nerve Neurosensory Disturbance Following Sagittal Split Osteotomy.

PURPOSE: Neurosensory disturbance (NSD) occurring in the lower lips and chin is a major postoperative complication related to bilateral sagittal split osteotomy (SSO). The purpose of this study is to identify preoperative radiographic findings following SSO procedure associated with persistent NSD. METHODS: This retrospective cohort study analyzed data for consecutive patients who underwent SSO. Primary predictor variables, including ramus width, mandibular body height, mandibular angle length, gonial angle, distance from mental foramen to distal aspect of mandibular second molar (MFD), and measurement of bone marrow space (BMS), were examined in a series of radiographic images. The primary outcome variable was NSD. Patients with NSD were divided into 2 groups based on findings obtained 1 year postoperatively: persistent, for those with NSD remaining after 1 year, and transient, when NSD occurred for less than 1 year. Covariates included sex and age. Comparisons were analyzed by use of Mann-Whitney U test or χ2 test. Multivariate analysis was performed using step-wise logistic regression to determine significant factors related to persistent NSD. A P value .005 or less was considered statistically significant. RESULTS: Of the 349 sides investigated, the persistent NSD group consisted of 59 sides (16.9%), while the transient NSD group consisted of 290 sides (83.1%). The occurrence of persistent NSD was correlated with age (P < .05), MFD (P < .001), mandibular body height (P < .05), and BMS (P < .001). Multivariate logistic analysis also showed a significant association of MFD (P < .001) and BMS (P < .001). CONCLUSIONS: Preoperative MFD and BMS are radiographic findings that are associated with an increased risk for persistent NSD following SSO procedure.

The Accuracy of Maxillary Position Using a Computer-Aided Design/Computer-Aided Manufacturing Intermediate Splint Derived Via Surgical Simulation in Bimaxillary Orthognathic Surgery.

PURPOSE: The purpose of this study was to assess the clinical interventions and the accuracy of maxillary reposition using a computer-aided design/computer-aided manufacturing (CAD/CAM) splint derived via surgical simulation. MATERIALS AND METHODS: The retrospective study comprised 24 patients who underwent bimaxillary surgery. The patients were assigned to 1 of 2 groups by a way of maxillary repositioning. One group received conventional intermediate wafers and the other CAD/CAM wafers during Le Fort I osteotomy. We recorded operation time, blood loss, the operative accuracy. Accuracy was analyzed by 3-dimensional computed tomography images before and immediately after the operation. The evaluation points were the right maxillary first incisor (U1), the right maxillary second molar (M2-right), and the left maxillary second molar (M2-left). RESULTS: The 2 groups did not differ significantly in operation time and blood losses. The vertical axis of U1 data differed significantly between the 2 groups (P = 0.008). None of the horizontal, vertical, or anteroposterior axis of M2-right data differed significantly, and anteroposterior axis of M2-left data differed significantly (P = 0.0296). The CAD/CAM group 3-dimensional distance errors were less than those of the conventional group for all points. CONCLUSION: Placement of CAD/CAM splint allowed highly accurate repositioning; the accuracy exceeded that afforded by conventional model surgery using a facebow and articulator.

A comparison of postoperative, three-dimensional soft tissue changes in patients with skeletal class III malocclusions treated via orthodontics-first and surgery-first approaches.

The aim of this retrospective study was to compare three-dimensional (3D) soft tissue and hard tissue changes between orthodontics-first approach (OFA) and surgery-first approach (SFA) after mandibular setback surgery. All patients underwent bilateral sagittal split osteotomy, and were examined by lateral cephalograms and 3D optical scanner before surgery (T0) and 1 (T1), 3 (T2), and 12 (T3) months after surgery. Three standard angles (FMA, U1 to FH, IMPA) were measured as hard tissue change and the 2 sets of 3D data were superimposed, and volumetric differences were calculated as soft tissue change. Statistical analyses were performed by using unpaired t-tests. Differences with P < 0.05 were considered significant. A total of 39 patients with mandibular prognathism were included in this study. The OFA group consisted of 24 patients and the SFA group of 15 patients. The SFA group exhibited more labial inclination from T1 to T2 (p = 0.008) and T2 to T3 (p = 0.003) than did the OFA group. There were no significant changes at maxilla and mandible at each term of T0, T1, T2 and T3 (p > 0.05), but compared to before surgery, mandibular volume in SFA group significant increased at 1year (p = 0.049) after surgery. We found that the soft tissue changes after the SFA differed significantly from those after the OFA; thus, soft tissue predictions require more care. An analysis of our data compared with OFA and SFA for the patient with mandibular prognathism confirm that the mandibular soft tissue changes by postoperative orthodontic treatment and occlusal relationship in SFA.

Pyramidal and posterior osseous release for maxillary superior/posterior mobilization using an ultrasonic bone-cutting device after Le Fort I osteotomy.

AIM: The purpose of this study was to evaluate the efficiency of pyramidal and posterior osseous release (PPOR) for maxillary impaction using an ultrasonic bone-cutting device after Le Fort I (LFI) osteotomy. MATERIALS AND METHODS: In total, 31 Japanese adults with jaw deformities, diagnosed as having maxillary excess with mandibular prognathism or deficiency, underwent LFI osteotomy and bilateral sagittal split osteotomy. The patients were divided into two groups: a trimming group (15 patients, four men and 11 women; mean age 24.8 years) and a PPOR group (16 patients, seven men and nine women; mean age 22.8 years). In the trimming group, osseous interference around the descending palatine artery (DPA) was removed using forceps, rounding bur, and reciprocating rasp. The PPOR technique was used to remove osseous fragments created by V-shaped osteotomy around the DPA following vertical osteotomy behind the DPA using an ultrasonic bone-cutting device (Variosurg 3; NSK, Tochigi, Japan). The operative times for maxillary osteotomy, total operative times (including bilateral sagittal split osteotomy), and total blood loss were assessed. RESULTS: The mean planned amounts of maxillary impaction were 4.37 ± 1.27 mm in the trimming group and 4.38 ± 1.36 mm in the PPOR group (p = 0.98). The mean maxillary operative time for the PPOR group was significantly shorter, by 25.5% (p < 0.001). Total operative time for the PPOR group was also significantly shorter, by 24.3% (p < 0.001). Mean blood loss was significantly lower in the PPOR group than in the trimming group (p = 0.003). CONCLUSION: The PPOR technique for maxillary impaction after LFI osteotomy shortened the operative time and enabled secure reduction of the maxilla in patients who required the treatment of maxillary impaction with preservation of the DPA bundle.

The relationship between neurosensory disturbance of the inferior alveolar nerve and the lingual split pattern after sagittal split osteotomy.

OBJECTIVE: The aim of this study was to evaluate the relationship between neurosensory disturbance (NSD) and the different types of bilateral sagittal split osteotomy (BSSO) lingual fracture created. STUDY DESIGN: The study group consisted of 45 patients with mandibular deformities (90 sides; 14 males and 31 females). Computed tomography (CT) scans were obtained preoperatively and 1 week postoperatively. All patients were divided into lingual fracture line groups on the basis of their postoperative scans. NSD was tested preoperatively and 1, 3, and 12 months postoperatively by using a sensory touch Semmes-Weinstein (SW) test and the 2-point discrimination (TPD) test. RESULTS: Patients were divided into 2 groups on the basis of their lingual fracture lines after mandibular BSSO; among the 45 patients, 39 sides (43.3%) had short-splits, and 51 sides (56.7%) had long-splits. The short-split group was less affected at all tested times, and the difference between the 2 groups was significant 1 month postoperatively on TPD test but not at other times on the both tests. CONCLUSIONS: The split type did not affect the NSD incidence at 3 and 12 months postoperatively.

[Basic Studies on the Mechanism, Prevention, and Treatment of Osteonecrosis of the Jaw Induced by Bisphosphonates].

Since the first report in 2003, bisphosphonate-related osteonecrosis of the jaw (BRONJ) has been increasing, without effective clinical strategies. Osteoporosis is common in elderly women, and bisphosphonates (BPs) are typical and widely used anti-osteoporotic or anti-bone-resorptive drugs. BRONJ is now a serious concern in dentistry. As BPs are pyrophosphate analogues and bind strongly to bone hydroxyapatite, and the P-C-P structure of BPs is non-hydrolysable, they accumulate in bones upon repeated administration. During bone-resorption, BPs are taken into osteoclasts and exhibit cytotoxicity, producing a long-lasting anti-bone-resorptive effect. BPs are divided into nitrogen-containing BPs (N-BPs) and non-nitrogen-containing BPs (non-N-BPs). N-BPs have far stronger anti-bone-resorptive effects than non-N-BPs, and BRONJ is caused by N-BPs. Our murine experiments have revealed the following. N-BPs, but not non-N-BPs, exhibit direct and potent inflammatory/necrotic effects on soft-tissues. These effects are augmented by lipopolysaccharide (the inflammatory component of bacterial cell-walls) and the accumulation of N-BPs in jawbones is augmented by inflammation. N-BPs are taken into soft-tissue cells via phosphate-transporters, while the non-N-BPs etidronate and clodronate inhibit this transportation. Etidronate, but not clodronate, has the effect of expelling N-BPs that have accumulated in bones. Moreover, etidronate and clodronate each have an analgesic effect, while clodronate has an anti-inflammatory effect via inhibition of phosphate-transporters. These findings suggest that BRONJ may be induced by phosphate-transporter-mediated and infection-promoted mechanisms, and that etidronate and clodronate may be useful for preventing and treating BRONJ. Our clinical trials support etidronate being useful for treating BRONJ, although additional clinical trials of etidronate and clodronate are needed.

Effect of "surgery first" orthognathic approach on temporomandibular symptoms and function: a comparison with "orthodontic first" approach.

OBJECTIVE: The aim of this study was to comparatively evaluate the effects of the surgery-first approach (SFA) and the orthodontics-first approach (OFA) on temporomandibular joint (TMJ) function and maximum mouth opening. STUDY DESIGN: This retrospective study investigated the outcomes of patients with diagnosed skeletal class III dentofacial deformities. Twenty-four patients were enrolled in the OFA group, and 23 patients were enrolled in the SFA group. All patients were examined in the same manner 4 times: before surgery and at 1, 3, 6, and 12 months after surgery. Range of mouth opening (ROM) was measured between the maxillary and mandibular central incisors. Symptoms were evaluated subjectively by using a questionnaire with items pertaining to pain on mandibular movements, TMJ sounds, and pain in masticatory muscles region. RESULTS: No severe complications or relapse occurred in either group during the 12-month follow-up period. Postoperative changes in ROM showed similar tendencies, but there was no significant difference in ROM during the follow-up period between the OFA and SFA groups (P < .05). The percentage reduction was nearly 45% at 1 month postoperatively and 20% at 3 months postoperatively compared with the preoperative situation. After 6 months postoperatively, the ROM was almost the same as before surgery. The number of patients with such sounds increased with time until 12-month postoperative examinations in the OFA group but increased slightly during this period in the SFA group. During the first 3 months postoperatively, less than 10% of patients in both groups had newly detected pain of TMJ and/or muscles. At 6 and 12 months postoperatively, only 1 patient in the SFA group had pain. CONCLUSIONS: No significant differences in TMJ symptoms or function were observed during a 12-month follow-up period between patients with skeletal class III malocclusion treated with the SFA and those treated with the OFA.

Increase in bone metabolic markers and circulating osteoblast-lineage cells after orthognathic surgery.

Increased mineralisation rate and bone formation after surgery or fracture is the regional acceleratory phenomenon (RAP), and its systemic impact is the systemic acceleratory phenomenon (SAP). The proportion of circulating osteoblast lineage cells, including osteocalcin-positive (OCN+) cells, in the peripheral blood is markedly higher during pubertal growth and in patients with bone fractures. This study aimed to elucidate the dynamic changes in bone metabolic activity after orthognathic surgery by longitudinal prospective observation. Peripheral venous blood samples were collected from patients who had undergone orthognathic surgery, and serum bone metabolic markers and the proportion of OCN+ cells were measured. Orthognathic surgery induces systemic dynamic changes in bone metabolic activity by targeting steps in the bone healing process and related proteins, such as surgical stress/inflammation (C-reactive protein), bone resorption (type I collagen C-telopeptide), and bone formation (alkaline phosphatase and bone-specific alkaline phosphatase). During the early post-operative period, the population of OCN+ cells significantly increased. Confocal microscopy revealed that OCN proteins were localised in the cytoplasm in Triton X-100-treated OCN+ cells. Furthermore, OCN, ALP, and COL1A1 gene expression was detected in OCN+ cells, suggesting the contribution of the local maturation of bone marrow-derived OCN+ cells at the site of bone healing.

Volumetric comparison of maxillofacial soft tissue morphology: computed tomography in the supine position versus three-dimensional optical scanning in the sitting position.

OBJECTIVE: Three-dimensional (3-D) surgical simulation has become popular, but the accuracy of such simulation is difficult to assess. Because maxillofacial soft tissue profiles vary with posture, we compared such profiles obtained in the supine and sitting positions. STUDY DESIGN: In total, 28 patients with skeletal Class III jaw deformities underwent computed tomography in the supine position and 3-D optical scanning in the sitting position. The 2 sets of 3-D data were superimposed, and linear and volumetric differences were calculated. We evaluated the cheeks, the subauricular and infraorbital regions, the nose, the lips, and the chin. Statistical analyses were performed by using paired Student's t tests. Differences with P < .05 were considered significant. RESULTS: Patients were divided into 3 groups based on body mass index. The facial profiles of the cheeks and subauricular areas differed significantly between the sitting and supine positions. The extent of variation increased with body mass index. CONCLUSIONS: When a patient moves from the sitting position to the supine position, maxillofacial soft tissue migrates from the cheeks to the subauricular regions. Thus, simulations for surgery based on supine computed tomography alone do not accurately model the cheeks and subauricular areas.