Effects of maxillary advancement on maxillary incisor display in patients with skeletal Class III malocclusion and cleft lip and palate.

INTRODUCTION: The information on the hard- and soft-tissue factors correlated with tooth display after LeFort I osteotomy, especially in the surgery-first approach (SFA), are limited. This study aimed to correlate different parameters with the maxillary incisor display in patients with skeletal Class III malocclusion and those with cleft lip and palate (CLP) in SFA. METHODS: This study consisted of 35 patients with skeletal Class III malocclusion and 32 with cleft deformities who had undergone orthognathic surgery. Pretreatment and posttreatment lateral cephalometric analysis were obtained. Maxillary incisor display was measured in photographs. The intraclass correlation coefficient was used to assess the intraexaminer repeatability. The Student t test was used to compare the maxillary incisor display between 2 groups. Analysis of covariance was performed with pretreatment measurement as covariates, and the important determinants for maxillary incisor display were identified by adjusting the baseline measurements. RESULTS: The mean increase of maxillary advancement at point A was 5.25 mm and 1.28 mm downward movement for skeletal Class III malocclusion, whereas it was 4.59 mm advancement and 2.16 mm downward movement for patients with CLP. The resulting maxillary incisor display was 2.86 mm for skeletal Class III malocclusion and 2.56 mm for patients with CLP. The covariates for maxillary incisor display before intervention was significantly associated with the maxillary incisor display after intervention (P <0.001). However, the interaction effect of groups was not seen (P = 0.933). The horizontal position of A, vertical position of ANS, and upper lip length were the most predictable parameters (P <0.001, P <0.001, P = 0.048, respectively) for maxillary incisor display in both groups. CONCLUSIONS: Horizontal position of point A, vertical position of ANS, and upper lip length are the most important determinants for maxillary incisor display for patients with skeletal Class III malocclusion and those with CLP.

Surgery-first accelerated orthognathic surgery: postoperative rapid orthodontic tooth movement.

PURPOSE: Clinically, we have observed the phenomenon of postoperatively accelerated orthodontic tooth movement in patients who had orthognathic surgery. This phenomenon lasts for a period of 3 to 4 months. However, the underlying mechanisms of this phenomenon have not been well studied yet. The purpose of this prospective clinical pilot study was to study the postoperative changes in bone physiology and metabolism and the corresponding responses in the dentoalveolus, such as the changes in tooth mobility. MATERIALS AND METHODS: Twenty-two consecutive adult patients who had 2-jaw orthognathic surgery were included in this study. The levels of serum alkaline phosphatase and C-terminal telopeptide of type I collagen (ICTP), as well as the tooth mobility of the maxillary and mandibular incisors based on the Periotest method (Siemens AG, Bensheim, Germany), were examined preoperatively and 1 week, 1 month, 2 months, 3 months, and 4 months postoperatively. The data were analyzed statistically. RESULTS: Both tooth mobility of the maxillary and mandibular incisors and ICTP significantly increased from 1 week to 3 months postoperatively and then decreased to their preoperative levels in the fourth month postoperatively. The changes in tooth mobility were significantly in correspondence with the changes in ICTP. The alkaline phosphatase level significantly increased from the first to fourth month postoperatively, but it was not significantly correlated to the changes in tooth mobility. CONCLUSION: The orthognathic surgery triggers a 3- to 4-month period of higher osteoclastic activities and metabolic changes in the dentoalveolus postoperatively, which possibly accelerates postoperative orthodontic tooth movement.

Surgery-first accelerated orthognathic surgery: orthodontic guidelines and setup for model surgery.

The surgery-first approach indicates that the orthognathic surgery precedes the orthodontic treatment, whereas the orthodontics-first approach indicates that the orthodontic treatment precedes the orthognathic surgery. The conventional approach is an orthodontics-first approach. The purposes of this article are to introduce the concept of the surgery-first approach and to report the guidelines for orthodontic management and model surgery without presurgical orthodontic decompensation. The surgery-first approach treats facial esthetics first and then occlusion, whereas the conventional approach treats occlusion first and then facial esthetics. The surgery-first approach uses osteotomy to solve both skeletal problems and dental compensation, and a "transitional" occlusion is set up postoperatively. Orthodontics in the surgery-first approach is a postoperatively adjunctive treatment to transfigure the transitional occlusion into the solid final occlusion. The advantages of the surgery-first approach are that 1) the patient's chief complaint, dental function, and facial esthetics are achieved and improved in the beginning of the treatment; 2) the entire treatment period is shortened to 1 to 1.5 years or fewer depending on the complexity of orthodontic treatment; and 3) the phenomenon of postoperatively accelerated orthodontic tooth movement reduces the difficulty and treatment time of orthodontic management in the surgery-first approach.

Comparison of progressive cephalometric changes and postsurgical stability of skeletal Class III correction with and without presurgical orthodontic treatment.

PURPOSE: This study compares 1) progressive dental and skeletal changes, 2) postsurgical stability, and 3) treatment efficacy of patients with skeletal Class III correction with and without presurgical orthodontic treatment. PATIENTS AND METHODS: The study includes 53 patients who underwent orthognathic surgery (OGS) to correct skeletal Class III malocclusion. The patient grouping is based on presurgical orthodontics: surgical-first (SF) approach (n = 18) and modified-conventional (MC) approach (n = 35). This study divides the MC group into 2 groups based on whether patients underwent tooth extraction in the presurgical phase (Ext group) (n = 10) or not (Nxt group) (n = 25). Serial lateral cephalometric film measurements identify skeletal and dental changes before treatment (T1), before OGS (T2), 1 month after OGS (T3), and at completion of treatment (T4). This investigation reviews the medical charts for treatment progress and duration. RESULTS: In the presurgical phase, the Ext group showed mild retraction of the upper incisors and more proclination of the lower incisors than the Nxt group. The skeletal sagittal parameters were similar from T1 to T4 in both the SF and MC groups. In the SF group, SN/U1 decreased 6.2° after surgery and was mildly proclined at T4; in the MC group, upper incisor inclination (SN/U1) increased 1.8° from T1 to T4, being 9.4° greater than that in the SF group at T4. The lower incisor inclination (MP/L1) was similar at T4 in both groups. In the MC group, the MP/L1 was shown to be proclined 4.5° before surgery, retroclined 1.9° after surgery, and further retroclined 4.5° until T4. The relapse rate of the mandibular setback was 14.3% in the SF group and 15.7% in the MC group without significant differences. The percentage of sagittal relapse less than 2 mm was 50% in the SF group and 54% in the MC group. The ratio was greater in the MC group with a relapse between 2 and 4 mm but lesser with a relapse greater than 4 mm. The Ext group showed a 3-month longer treatment duration than the Nxt group. CONCLUSION: The amount of skeletal correction and postsurgical relapse, as well as treatment duration, were no different in Class III OGS patients with or without presurgical orthodontic treatment. The presurgical work of lower incisor proclination returned to an inclination similar to the initial status after completing treatment. The final outcome of patients evidenced no difference in lower incisor inclination, with or without presurgical orthodontics.

Comparison of transverse dimensional changes in surgical skeletal Class III patients with and without presurgical orthodontics.

PURPOSE: To investigate transverse dimensional changes of dental arches in surgical skeletal Class III patients with and without presurgical orthodontics. MATERIALS AND METHODS: Thirty-six patients with skeletal Class III were included and grouped into those with or without presurgical orthodontics. Eighteen patients (mean age, 22.3 +/- 3.8 years) with presurgical orthodontics (mean presurgical orthodontic treatment time, 176.3 +/- 38.3 days) were in the orthodontics-first (OF) group; the other 18 patients (mean age, 23.3 +/- 4.2 years) without presurgical orthodontics were in the surgery-first (SF) group. The posteroanterior cephalograms initially, before surgery, immediately after surgery, and 1 year after surgery were traced and analyzed. The inclination change of canines and molars was measured to interpret the changes of transverse dimension in both dental arches. Paired and unpaired t tests were performed to test intra- and intergroup differences (P < .05). RESULTS: Dental changes in transverse planes demonstrated a similar trend in both groups. The maxillary canines were buccally tilted (SF vs OF group, 1.7 degrees vs 1.9 degrees), the maxillary molars were lingually tilted (SF group vs OF group, -4.7 degrees vs -1.0 degrees), the mandibular canines were lingually tilted (SF group vs OF group, 2.9 degrees vs 2.8 degrees), and the mandibular molars were buccally tilted (SF group vs OF group, -6.1 degrees vs -5.4 degrees). CONCLUSION: The magnitude and trend of transverse dental changes in patients with surgical skeletal Class III were similar whether receiving presurgical orthodontics or not.

Comparison of the loading behavior of self-drilling and predrilled miniscrews throughout orthodontic loading.

INTRODUCTION: A predrilled miniscrew, when used as a temporary anchorage device in the infrazygomatic crest of the maxilla, can be displaced under orthodontic loading. The purpose of this retrospective cephalometric study was to compare the loading behavior of predrilled and self-drilling miniscrews placed in the infrazygomatic crest of the maxilla. METHODS: The subjects were 32 women who had miniscrews in the infrazygomatic crest of the maxilla as skeletal anchorage for en-masse anterior retraction and intrusion; 16 had predrilled miniscrews, and 16 had the self-drilling type. The miniscrews were all 2 mm in diameter and 10 to 17 mm long. They were loaded with nickel-titanium closed-coil springs 2 weeks after placement. All the miniscrews remained stable, without detectable mobility or loosening, throughout the treatment period. Cephalometric radiographs were taken immediately before force application (T1) and at least 5 months later (T2). The T1 and T2 cephalometric tracings were superimposed to determine whether any displacement of the miniscrews had occurred. RESULTS: The predrilled and self-drilling miniscrews were all significantly displaced in accordance with the force direction of the nickel-titanium coil springs. The amounts of miniscrew displacement were similar between the predrilled and self-drilling miniscrews, and were correlated to the length of the loading period. The displacements were 0.0 to 1.6 mm with extrusion, 1.5 mm with forward or backward tipping at the screw tail, and 1.5 mm with forward tipping at the screw head. CONCLUSIONS: The loading behaviors of predrilled and self-drilling miniscrews were similar in the infrazygomatic crest of the maxilla. These miniscrews were all subject to displacement under orthodontic loading, and the amount of the displacement was correlated to the length of the loading period, although they remained stable without detectable mobility or loosening.

A computed tomographic image study on the thickness of the infrazygomatic crest of the maxilla and its clinical implications for miniscrew insertion.

INTRODUCTION: The purpose of this study was to measure the thickness of the infrazygomatic (IZ) crest above the maxillary first molar at different angles and positions to the maxillary occlusal plane. These measurements were then used to derive clinical implications and guidance for inserting miniscrews in the IZ crest without injuring the mesiobuccal root of the maxillary first molar. METHODS: Computed tomographic images of 16 adults were used. For each subject, on the coronal slice of the computed tomographic image containing the IZ crest and mesiobuccal root of the maxillary first molar, the IZ crest thickness and the miniscrew insertion position were measured by postulating that the miniscrew would be inserted at each 5 degrees increment from 40 degrees to 75 degrees to the maxillary occlusal plane. RESULTS: The IZ crest thickness above the maxillary first molar ranged from 5.2 +/- 1.1 mm to 8.8 +/- 2.3 mm, measured at 40 degrees to 75 degrees to the maxillary occlusal plane and 13 to 17 mm above the maxillary occlusal plane. CONCLUSIONS: By adopting 6 mm as the minimal IZ crest thickness for sustaining a miniscrew well throughout treatment and avoiding injury to the mesiobuccal root of the maxillary first molar, the clinical implication for miniscrew placement in the IZ crest of an adult is to insert it 14 to 16 mm above the maxillary occlusal plane and the maxillary first molar at an angle of 55 degrees to 70 degrees to the maxillary occlusal plane.

Comparative outcomes of two nasoalveolar molding techniques for bilateral cleft nose deformity.

BACKGROUND: Bilateral cleft nose deformity is increasingly being treated before primary repair with nasoalveolar molding. With the Grayson technique, nasal molding is started when the alveolar gap is reduced to 5 mm, whereas with the Figueroa technique, nasal molding and alveolar molding are performed at the same time. Both techniques significantly lengthen the columella, but their comparative efficacy, efficiency, and incidence of complications have not been investigated. METHODS: In this blinded, retrospective study of 58 patients with complete bilateral cleft lip-cleft palate, 27 underwent Grayson nasoalveolar molding and 31 underwent Figueroa nasoalveolar molding. Outcomes were compared by analyzing pretreatment and posttreatment facial photographs and clinical charts for efficacy (i.e., columella length ratio, alar width ratio, alar base width ratio, nostril shape, nasal tip angle, nasolabial angle, and nasal base angle), efficiency (i.e., molding frequency), and incidence of complications (e.g., facial irritation and oral mucosal ulceration). RESULTS: Grayson and Figueroa nasoalveolar molding did not differ in treatment efficacy for columellar length ratio, alar width ratio, alar base width ratio, nostril shape, nasal tip angle, nasolabial angle, or nasal base angle (all p > 0.05). Grayson nasoalveolar molding was less efficient (i.e., required more adjustments) (10.8 ± 4.1 versus 7.6 ± 1.5; p = 0.001) and had a higher incidence of oral mucosal ulceration (26 percent versus 3 percent; p < 0.05). CONCLUSIONS: Both Grayson and Figueroa nasoalveolar molding similarly improve nasal deformities and reduce alveolar gaps; however, the Figueroa technique is associated with fewer oral mucosal complications and more efficiency.

The inter-relationship between mandibular autorotation and maxillary LeFort I impaction osteotomies.

The purposes of the present investigation were to: 1)locate the instantaneous rotation center of mandible autorotation during maxillary surgical impaction; 2) identify the discrepancies between the resultant mandibular position following by maxillary surgical impaction and presurgical predictions, which use the radiographic condylar center as the rotation center for mandibular autorotation; and 3)find the interrelation between the magnitude of maxillary surgical impaction and the sagittal change of mandible. Ten patients underwent maxillary LeFort I impaction without concomitant major mandibular ramus split osteotomies were included. The preoperative (T0) and postoperative (T1) lateral cephalograms were used to evaluate the surgical changes and locate the center of rotation of mandibular autorotation with Reuleaux method. Prediction errors were measured by comparing the predicted (Tp) and postoperative (T1) cephalometric tracings. The magnitude of the maxillary surgical impaction was compared to the positional changes of mandible after mandibular autorotation with correlation and regression analysis. The results demonstrated that the centers of mandibular autorotation located 2.5 mm behind and 19.6 mm below the radiographic condylar center of the mandible in average with large individual variations. By using the radiographic condylar center of the mandible to predict the mandibular autorotation would overestimate the horizontal position of chin by 2 mm and underestimate the vertical position of chin by 1.3 mm following an average of 5 mm surgical maxillary impaction. The magnitude of maxillary impaction was highly and positively correlated to the horizontal displacement of chin position. The rotation centers of mandibular autorotation following by maxillary LeFort I impaction osteotomies might not usually locate at the radiographic condylar center of the mandible also with large individual variations in their positions. Surgeons and orthodontists should be aware of the horizontal and vertical discrepancies of chin positions while planning a two-jaw surgery by using the radiographic center of mandibular condyle as the rotation center in mandibular autorotation.