Preliminary study: evaluating the reliability of CBCT images for tongue space measurements in the field of orthodontics.

INTRODUCTION: Accurately measuring tongue space is challenging, but this information can be useful to many dental specialties. This study was intended to estimate the reliability of using cone-beam computed tomography (CBCT) to measure tongue space, which includes tongue volume and the oral cavity air capacity. METHODS: For this preliminary study, CBCT images from ten participants (five females and five males, mean age of 29.8 ± 3.3 years) were available for evaluation. Each participant was radiographed two times (T0 and T1). The average time between T0 and T1 was 15.8 ± 3.7 days. CBCT scans were standardized to reduce variability. Three-dimensional landmarks were established to identify tongue space and 3D image analysis software (SimPlant® 17 Pro; Materialise Dental, Leuven, Belgium) was used to measure the volume circumscribed by the landmarks. Two investigators independently calculated airway, tongue dimensions, and total tongue space for CBCT image T0 twice (day 1 and day 14), and T1 once. Intraclass correlation coefficients (ICCs) were used to estimate intra-rater and inter-rater reliability. Bland-Altman charts were constructed to demonstrate agreement within and between raters. RESULTS: The intra-rater and inter-rater ICCs of the CBCT measurements at T0 were excellent (> 0.90). Measurements for T0 vs. T1 show good (0.75-0.90) intra-rater and excellent (> 0.90) inter-rater reliability. Bland-Altman charts show that 90-95% of the total measurements fall within the 95% limits of agreement for both intra- and inter-rater pairs CONCLUSIONS: The results of this preliminary study suggest that the landmarks chosen to measure the overall tongue space are reproducible and can be measured clearly using CBCT.

History and Evolution of Orthognathic Surgery at Chang Gung Craniofacial Center: Lessons Learned From 35-Year Experience.

BACKGROUND: Modern orthognathic surgery (OGS) was established on the basis of contributions from multidisciplinary centers worldwide. This study reports the history and evolution of OGS at the Chang Gung Craniofacial Center (CGCC) and identifies the lessons learned from 35 years of experience. METHODS: The total number of OGS procedures managed by the CGCC multidisciplinary team between 1981 and 2016 was determined. The database of the senior author (Y.-R.C.) was reviewed for consecutive OGS procedures performed between 2003 and 2016. A literature review was also performed to retrieve the contributions from the total CGCC team. RESULTS: The 35 years of experience at a single center and 13-year experience of a single surgeon corresponded to 8073 and 2883 OGS procedures, respectively. Moreover, 53 peer-reviewed articles were reviewed. Teamwork (plastic surgeons, orthodontists, and anesthetists) ensured an optimal balance between occlusion functional and facial aesthetic outcomes, with patient safety ensured and a minimum of OGS-related complications. Progression from the conventional orthodontics-first approach to the surgery-first OGS approach decreased the overall treatment time. Transition from 1-jaw to 2-jaw surgery enabled more consistent aesthetic outcomes to be achieved. Conversion from the 2-splint to the single-splint technique enabled development of a more precise tridimensional simulation plan and surgical execution, including in challenging scenarios such as malocclusion associated with facial asymmetry. Clockwise pitch rotation of the maxillomandibular complex has been designed for facial aesthetic purposes in class III malocclusion, whereas counterclockwise pitch rotation of the maxillomandibular complex improves airway function in those with sleep apnea. CONCLUSIONS: The lessons learned from experience and outcome-based articles reveal that OGS has successfully evolved at the CGCC, with a balance being achieved between functional and aesthetic outcomes and effective decreases in the burden of care (ie, morbidity, complications, and treatment time).

Three-dimensional surgical simulation improves the planning for correction of facial prognathism and asymmetry: A qualitative and quantitative study.

Traditional planning method for orthognathic surgery has limitations of cephalometric analysis, especially for patients with asymmetry. The aim of this study was to assess surgical plan modification after 3-demensional (3D) simulation. The procedures were to perform traditional surgical planning, construction of 3D model for the initial surgical plan (P1), 3D model of altered surgical plan after simulation (P2), comparison between P1 and P2 models, surgical execution, and postoperative validation using superimposition and root-mean-square difference (RMSD) between postoperative 3D image and P2 simulation model. Surgical plan was modified after 3D simulation in 93% of the cases. Absolute linear changes of landmarks in mediolateral direction (x-axis) were significant and between 1.11 to 1.62 mm. The pitch, yaw, and roll rotation as well as ramus inclination correction also showed significant changes after the 3D planning. Yaw rotation of the maxillomandibular complex (1.88 ± 0.32°) and change of ramus inclination (3.37 ± 3.21°) were most frequently performed for correction of the facial asymmetry. Errors between the postsurgical image and 3D simulation were acceptable, with RMSD 0.63 ± 0.25 mm for the maxilla and 0.85 ± 0.41 mm for the mandible. The information from this study could be used to augment the clinical planning and surgical execution when a conventional approach is applied.

Interdental osteotomies induce regional acceleratory phenomenon and accelerate orthodontic tooth movement.

PURPOSE: Although it has been revealed clinically that double-jaw orthognathic surgery induces a systemic increase in the baseline bone turnover and subsequently accelerates postoperative orthodontic tooth alignment, it is not clear whether less extensive osteotomy, such as interdental osteotomy, would be intensive enough to accelerate postoperative orthodontic tooth alignment. MATERIALS AND METHODS: Twelve adult male beagle dogs were randomly assigned to 2 groups. The sham control group (n = 6) received orthodontic tooth alignment of the maxillary incisors, and the experimental group (n = 6) received orthodontic tooth alignment of the maxillary incisors and interdental osteotomies between the maxillary third incisor and canine on both sides concurrent with the beginning of orthodontic tooth alignment. The duration of orthodontic tooth alignment was 3 months in both groups. Cone-beam computed tomography scans of the maxilla, dental casts, blood samples, and gingival crevicular fluid (GCF) of the maxillary incisors were taken immediately before orthodontic tooth alignment (T0) and 1 week (T1) and 1 (T2), 2 (T3), and 3 (T4) months after beginning orthodontic tooth alignment. They were analyzed for changes in the interdental alveolar bone gray scale (osteoporosity) of the maxillary incisors, irregularity index (rate of orthodontic tooth alignment), and bone-specific alkaline phosphatase (bALP, a biomarker of osteoblastic activity) and C-terminal telopeptide of type I collagen (ICTP, a biomarker for osteoclastic activity) in the serum and GCF samples from T0 to T4. The data were analyzed statistically for inter- and intragroup differences. RESULTS: The rate of orthodontic tooth alignment for the experimental group was significantly greater and twofold that of the sham control group at T1, T2, T3, and T4. The serum-bALP, serum-ICTP, GCF-bALP, GCF-ICTP, and osteoporosity remained similar from T0 to T4 in the sham control group. In contrast, GCF-bALP increased two- to threefold from T1 to T4, and GCF-ICTP increased fivefold at T1 and then gradually decreased from T2 to T4. The interdental osteoporosity significantly increased from T1 to T4, but the serum-bALP and serum-ICTP levels remained similar, without significant changes in the experimental group. CONCLUSIONS: Interdental osteotomy induced a regional, but not a systemic, acceleratory phenomenon and was intensive enough to accelerate postoperative orthodontic tooth alignment twofold. The intensity of the increase in the bone turnover rate and osteoporosity might depend on the extent of the osteotomy.

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.

Apical root resorption in orthodontic patients with en-masse maxillary anterior retraction and intrusion with miniscrews.

INTRODUCTION: The purposes of this retrospective study were to investigate the apical root resorption of maxillary incisors in orthodontic patients with en-masse maxillary anterior retraction and intrusion with miniscrews and the factors disposing a patient to apical root resorption. METHODS: Fifty adult patients with maxillary protrusion were included; 30 were treated with miniscrews and extraction of the maxillary first premolars (group I), and 20 were treated with extraction of the maxillary first premolars (group II). For each patient, periapical films of the maxillary incisors and lateral cephalometric radiographs were taken before and after treatment to evaluate apical root resorption and cephalometric measurements. The intergroup differences were analyzed with the Student t test and the correlations between apical root resorption and cephalometric measurements were analyzed by the Pearson correlation. RESULTS: The apical root resorption values were 16.0% to 20.0% (2.5-2.8 mm) in group I and 13.4% to 14.4% (2.1-2.3 mm) of the original root length in group II. Group I had significantly more severe Class II jaw discrepancy (ANB, 7.1 degrees +/- 1.9 degrees ) than did group II (ANB, 3.2 degrees +/- 2.9 degrees ). The amount of maxillary en-masse anterior retraction (8.2 +/- 2.4 mm), the duration of treatment (28.3 +/- 7.3 months), and apical root resorption of maxillary lateral incisors were significantly greater in group I than in group II. Apical root resorption of the maxillary central incisors was significantly correlated to the duration of treatment but not to the amount of en-masse retraction, intrusion, or palatal tipping of maxillary incisors. CONCLUSIONS: Miniscrew anchorage allows for more maxillary en-masse anterior retraction in patients with severe Class II cases. But the time needed for the greater amount of maxillary en-masse anterior retraction with miniscrew anchorage is longer and might dispose the patient to more apical root resorption.

A Surgery-first approach in surgical-orthodontic treatment of mandibular prognathism--a case report.

The conventional approach in orthodontic surgery treatment of dentofacial anomalies requires a varied period of pre-surgical orthodontic treatment. This presurgical period is considered to be important for adequate surgical treatment and stable results. This period is usually long bothersome for patients because dental decompensation is required and there is consequent deterioration of aesthetics and function, especially in cases of skeletal Class III occlusion. At Chang Gung Craniofacial Center, a surgery-first approach (SFA), i.e. minimal pre-surgical orthodontics, is one of the treatment choices for Class III patients. In this report, we present a 19-year-old man with mandibular prognathism, an anterior open bite and severe dental crowding treated with SFA. The patient received orthognathic surgery a week after bracing of the teeth. The operation and recovery were uneventful as well as the following orthodontic treatment. The total treatment time was only four months, much shorter than with the conventional approach. The patient benefitted from immediate improvement of the facial profile after surgery, and a much shorter total treatment, and the results were not compromised. We believe in selected cases, SFA is a good and effective treatment alternative.

Dental and skeletal changes following surgically assisted rapid maxillary anterior-posterior expansion.

BACKGROUND: Lengthening the maxillary dental arch as a treatment approach for patients with maxillary deficiency and dental crowding is seldom reported. The purpose of this study was to assess dental and skeletal changes in the maxilla in the correction of maxillary deficiency associated with a retruded maxillary arch using a surgically assisted rapid maxillary anterior-posterior expansion appliance. METHODS: Predistraction and postraction lateral cephalometric and periapical radiographs and maxillary dental casts of six young adolescents (four boys, two girls, mean age 11 years, 2 months) were examined. These patients received a maxillary anterior segmental osteotomy and distraction osteogenesis with an anteroposteriorly oriented Hyrax expansion appliance based on the biological principles of bone distraction. RESULTS: The retruded dental arch and dental crowding were successfully corrected. Significant forward movement of the point anterior nasal spine, point A, central incisors and first premolars was noted. The maxillary dental arch depth increased an average of 4.2 mm while the arch width remained unchanged. In total, 11.5 mm of dental space was created in the maxillary arch which was sufficient to resolve dental crowding. New bone formation along the distraction site was observed three months after distraction. CONCLUSIONS: The use of maxillary anterior segmental osteotomy combined with a Hyrax expansion distraction appliance was effective in arch lengthening and creation of dental space. An overcorrection in this interdental distraction osteogenesis could be a good treatment option for children with maxillary deficiency combined with crowded maxillary dentition.

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 comparative evaluation of current orthodontic miniscrew systems.

Miniscrew placement has achieved widespread acceptance in orthodontic practice. However, selecting a suitable miniscrew system from among the available brands is not easy. The aim of this article is to help the clinician better understand the features of miniscrew systems currently available on the market and provide a useful guideline for their clinical use. The authors find that the ideal miniscrew design should include biocompatibility, bone-density-guided insertion, immediate loading, and compatibility with modern orthodontic accessories for 3-dimensional orthodontic control.

Long-term follow-up after maxillary distraction osteogenesis in growing children with cleft lip and palate.

OBJECTIVE: To evaluate the changes in maxillary position after maxillary distraction osteogenesis in six growing children with cleft lip and palate. DESIGN: Retrospective, longitudinal study on maxillary changes at A point, anterior nasal spine, posterior nasal spine, central incisor, and first molar. SETTING: The University Hospital Craniofacial Center. MAIN OUTCOME MEASURE: Cephalometric radiographs were used to measure the maxillary position immediately after distraction, at 6 months, and more than 1 year after distraction. RESULTS: After maxillary distraction with a rigid external distraction device, the maxilla (A point) on average moved forward 9.7 mm and downward 3.5 mm immediately after distraction, moved backward 0.9 mm and upward 2.0 mm after 6 months postoperatively, and then moved further backward 2.3 mm and downward 6.8 mm after more than 1 year from the predistraction position. CONCLUSION: In most cases, maxilla moved forward at distraction and started to move backward until 1 year after distraction, but remained forward, as compared with predistraction position. Maxilla also moved downward during distraction and upward in 6 months, but started descending in 1 year. There also was no further forward growth of the maxilla after distraction in growing children with clefts.

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.

Distraction osteogenesis in adolescents with maxillary arch deficiency and dental crowding: a 3-year follow-up.

BACKGROUND: In this study, the authors evaluated the long-term results after using anterior segmental osteotomy and distraction osteogenesis for the correction of sagittal maxillary deficiency associated with dental crowding. METHODS: Six young adolescents (four boys and two girls) underwent surgery and distraction at a mean age of 11.2 years (range, 10 to 12 years) and were followed up for 3 years. A tooth-borne distraction device was used for interdental distraction. The evaluation consisted of hard- and soft-tissue profile analysis and dental arch measurements before, immediately after, and 3 years after distraction. RESULTS: The results showed that the facial profile, the occlusion, and the dental crowding could be successfully corrected and that the results were stable after 3 years' follow-up. The mean facial convexity angle was changed from 1 to 8 degrees. The average advancement at point A was 4 mm and the SNA increased by an average of 4 degrees. Lengthening of the dental arch by an average of 4 mm created approximately 8 mm of new space, sufficient to resolve the dental crowding in all patients, thus avoiding an extraction of healthy teeth. CONCLUSION: The results of this study demonstrated that anterior segmental maxillary osteotomy combined with distraction osteogenesis offers an alternative for the treatment of adolescents suffering from sagittal maxillary deficiency with dental crowding.

Mandibular remodeling after bilateral sagittal split osteotomy for prognathism of the mandible.

PURPOSE: To describe the postoperative remodeling changes in the mandible after bilateral sagittal split osteotomy to correct mandibular prognathism. PATIENTS AND METHODS: Twenty patients who underwent bilateral sagittal split osteotomy for the correction of mandibular prognathism were studied for postoperative remodeling changes within the mandible. The 6-week, 1-year, and long-term postoperative cephalometric mandibular tracings of 12 patients were superimposed using the fixation wires as the stable reference points to demonstrate the specific locations of the intrabony remodeling. RESULTS: There was a general direction of remodeling at the condylion and gonion anteriorly and superiorly, while the B point and pogonion did not show much change in remodeling. At the condylion, 60% and 40% of the cases showed significant horizontal and vertical remodeling, respectively. At the gonion, 50% and 55% of the cases showed significant horizontal and vertical remodeling, respectively. No correlation was found between the remodeling changes at condylion and gonion and the surgical movement or relapse at B point and pogonion. There was a significant correlation between the observed horizontal relapse at gonion and the horizontal remodeling changes at this point showing that the postoperative displacement of this point is a result of both positional translocation and remodeling changes. CONCLUSION: The results of this study show that there are intrabony remodeling changes that occur in the mandible after sagittal split osteotomy and that these continue for a long period of time in some patients. This remodeling occurred more in the condylar and gonial areas, while the chin remained relatively stable.