Skeletal and dental effects of tooth-borne versus hybrid devices for mandibular symphyseal distraction osteogenesis

Objective: To evaluate and compare, retrospectively, the skeletal and dental effects of mandibular symphyseal distraction osteogenesis (MSDO) achieved through the use of tooth-borne versus hybrid distractors.Materials and Methods:Pretreatment (T1), predistraction (T2), postdistraction (T3), and posttreatment (T4) orthodontic records were collected and analyzed for 47 patients (20 tooth-borne, 27 hybrid). At each time point, records included intraoral photographs, study models, postero-anterior cephalometric radiographs, and lateral cephalometric radiographs. Submental vertex radiographs were taken at T2, T3, and T4. Changes in a total of 18 measurements were analyzed to compare patients undergoing tooth-borne versus hybrid distraction.Results:The cumulative effects of orthodontics and MSDO produced similar gains in measured arch widths, with a decreased irregularity index in both groups (P > .05). However, there were differences in the timing during which the expansion was achieved. The hybrid distractor group gained space during the distraction phase of treatment. The tooth-borne group showed greater gains during pre- and postdistraction orthodontics. Comparisons of intercanine and interbone marker widths demonstrated a more parallel separation of bone during distraction with the hybrid distractor (P < .001). Distraction with the tooth-borne distractor was disproportionate, with greater separation of the canines in alveolar bone than of the bone markers in basal bone. During postdistraction orthodontics, the tooth-borne distractor group showed statistically greater increases in measurements.Conclusion:Both skeletal and dental expansion was achieved with both appliances. Greater skeletal expansion was achieved with a hybrid distractor. Greater dental expansion was achieved with a tooth-borne distractor.     

Mandibular symphyseal distraction osteogenesis: review of three techniques

Mandibular symphyseal distraction osteogenesis (MSDO) is an alternative strategy to correct mandibular transverse deficiencies and dental crowding. Only a limited number of practitioners have reported their clinical experience and potential complications of this procedure to widen the mandible in a large case series. This study involved retrospective analysis of 40 patients who underwent mandibular symphyseal distraction osteogenesis. Three different types of distractor were used to widen the mandible: tooth-borne in 21 patients, bone-borne in 5 patients and hybrid (both bone and tooth-borne) in 14 patients. The distraction amount ranged from 7 to 11 mm (mean 7.31 mm). While 39 patients underwent successful mandibular symphyseal distraction, there was one failure. Most of the complications were experienced in bone-borne distractors, such as breakage of the distractor rod, gingival recession, secondary infection and ptosis of the chin. In the light of these findings, it is suggested that a lingually placed tooth-borne hyrax appliance is more suitable and reliable than the other distraction devices. Further larger studies are needed in order to better evaluate the effectiveness of bone-borne or hybrid devices.     

A comparison of the Herbst and Fr?nkel appliances in the treatment of Class II malocclusion

This study investigated the treatment effects produced by two types of functional appliance, one primarily tooth-borne (the Herbst appliance) and one primarily tissue-borne (the FR-2 of Fr?nkel). Serial cephalometric radiographs from 45 patients who had been treated with the acrylic splint Herbst appliance and from 41 patients who had been treated with the FR-2 appliance were compared with serial radiographs of 21 untreated persons with Class II malocclusions. Treatment effects were identified through the use of a conventional cephalometric analysis. The results of this study indicated that both appliances had influenced the growth of the craniofacial complex in treated persons. Significant skeletal changes were noted in both treatment groups, with both groups showing an increase in mandibular length and in lower facial height, as compared with controls. Greater dentoalveolar treatment effects were noted in the group wearing the tooth-borne functional appliance than in those wearing the tissue-borne appliance.     

Nonextraction treatment with rapid maxillary expansion and mandibular symphyseal distraction osteogenesis and vertical skeletal dimensions

OBJECTIVE: To investigate the effects of rapid maxillary expansion (RME) and mandibular symphyseal distraction osteogenesis (MSDO) on vertical dimensions of the face. MATERIALS AND METHODS: Fourteen patients, nine girls and five boys, underwent RME and MSDO procedures. Distraction was carried out at a rate of 1 mm per 24 hours with a tooth-borne appliance. The amount of distraction was 7 mm for each patient. Standardized lateral cephalograms were taken at the following time periods: before treatment (T0), after RME (T1), at the completion of MSDO (T2), and at the end of fixed orthodontic treatment (T3). The data were evaluated by using a general linear model of repeated-measures analysis of variance and paired t-tests at the 95% confidence level. RESULTS: RME significantly increased the vertical dimensions of the face and decreased the overbite (P < .001). Although the vertical parameters of the face on the lateral cephalogram decreased after MSDO, these decreasing effects were statistically insignificant just for the distances measured from the horizontal reference line to the chin points. In other words, MSDO decreased the vertical skeletal dimensions that were increased by RME, but this neutralizing effect of MSDO was not as much as the increase caused by RME. CONCLUSION: Treatment modalities (RME, MSDO, and fixed orthodontic treatment) described in this study, in total, had little effect on the vertical skeletal measurements of the face.     

Long-term results of bilateral mandibular distraction osteogenesis using an intraoral tooth-borne device in adult Class II patients

The aim of this prospective clinical study was to evaluate the short-term and long-term skeletal and dental changes after mandibular osteodistraction with tooth-borne appliances in adult orthodontic patients. The sample consisted of 10 non-growing Caucasian patients with a Class II skeletal relationship due to mandibular deficiency, together with Class II dental malocclusion. All patients underwent mandibular distraction osteogenesis (MDO) using the ROD1 tooth-borne device. Lateral cephalograms were evaluated at four time intervals: pretreatment (T1), after mandibular distraction (T2), after orthodontic fixed appliance therapy (T3), and at long-term observation 8-year post-distraction (T4). Statistical analyses compared the skeletal and dental changes in intervals T1–T2, T2–T3, T3–T4, T1–T4, and T2–T4. MDO with the ROD1 tooth-borne device produced significant long-term (T1–T4) increases in the SNB angle (2.3°), total mandibular length (5.9 mm), and corpus length (4.5 mm). Potential adverse sequelae included significant increases in mandibular plane angle (4.3°), lower anterior dental height (2.8 mm), and lower posterior dental height (2.5 mm). Significant increases in lower incisor proclination occurred during distraction (7.5°). Distraction osteogenesis with tooth-borne appliances offers a minimally invasive surgical method with stable results for correcting mandibular deficiency in non-growing patients.     

Mandibular distraction osteogenesis in hemifacial microsomia: Long-term follow-up

AIM: Prospective, longitudinal, clinical long-term follow-up study of a homogeneous sample of children affected by hemifacial microsomia and treated by mandibular distraction osteogenesis. MATERIAL: Eight patients affected by types I and II hemifacial microsomia were operated on at an average age of 5.6 years with an average follow-up of 5.8 years. METHODS: Vertical changes were measured on postero-anterior cephalometric and panoramic radiographs taken sequentially. RESULTS: Angular changes of the infraorbital and nasal floor planes were not significant, showing that distraction osteogenesis starting after 5 years of age did not influence the maxillary skeletal base. Occlusal (plane) cant was reduced by 7 degrees on average following distraction osteogenesis, showing good dentoalveolar plasticity. Mandibular vertical changes showed a gradual return of the asymmetry, with growth in all patients (the ratio between affected and non-affected rami returned by 77% of the correction obtained by means of distraction 5 years postoperatively). CONCLUSION: Although aesthetic and psychological advantages of distraction osteogenesis are well accepted it should only be applied after careful patient selection and honest explanation of the long-term recurrence by genetically determined craniofacial growth patterns.     

Mandibular symphyseal distraction osteogenesis: 20 years of experience treating transverse deficiencies with an internal hybrid device

Introduction

Transverse mandibular deficiency has been traditionally managed by orthodontic compensation. However, without resolving the underlying skeletal hypoplasia it leads to high relapse rates. Few studies have reviewed the long-term experience and potential complications of mandibular symphyseal distraction osteogenesis (MSDO) as an alternative treatment method.

Mandibular widening by intraoral distraction osteogenesis

Transverse mandibular deficiency with crowding of the mandibular anterior teeth is frequently present in patients with Class I and II malocclusions. The hallmarks of treatment by compensating orthodontics, functional appliances or orthopaedic devices are instability, compromised periodontium and compromised facial aesthetics. A new surgical technique has been developed to widen the mandible. The method is based upon gradual osteodistraction following vertical interdental symphyseal osteotomy. Ten patients with transverse mandibular deficiency and significant dental crowding were treated by symphyseal distraction and subsequent non-extraction decompensating orthodontic treatment. Either an intraoral tooth-borne Hyrax appliance or a new custom-made bone-borne osteodistractor was used to gradually widen the mandible. The surgical procedures were accomplished under local anaesthesia and intravenous sedation in an ambulatory surgical setting using an individualized distraction protocol. The appliances were activated 7 days after symphyseal osteotomies, once each day at a rate of 1 mm per day and stabilized for 30–60 days after distraction. After the segments were distracted, non-extraction orthodontic alignment of the mandibular anterior teeth was accomplished. The symphyseal distraction gaps were bridged by new bony regenerate. Distraction osteogenesis provided an efficient surgical alternative to orthognathic surgery for widening the mandible and treatment of transverse mandibular deficiency without extraction of teeth.     

Evaluation of maxillary central incisors on the noncleft and cleft sides in patients with unilateral cleft lip and palate—Part 1: Relationship between root length and orthodontic tooth movement

Objectives:To measure the root lengths of maxillary central incisors (U1) and evaluate the relationship among U1 root length, tooth movement, and type of treatment appliance in patients with unilateral cleft lip and palate over a long-term follow-up period.Materials and Methods:Occlusal radiographs of 30 patients with unilateral cleft lip and palate, acquired less than 6 months before secondary alveolar bone grafting (SBG, T1) and after edgewise treatment (T2), were measured for U1 root length (R1 and R2, root lengths at T1 and T2, respectively). Frontal and lateral cephalometric radiographs acquired at eruption of U1 (T0), T1, and T2 were evaluated to determine the inclination and position of U1.Results:The average values of R1 and R2 on the cleft side were significantly lower than those on the noncleft side. Frontal cephalometric analysis revealed that the horizontal distance of the root apex from the median vertical line at T0 on the cleft side was significantly smaller than that on the noncleft side and was correlated with short U1 root length on the cleft side. On the other hand, R1 in patients treated with maxillary protraction appliances between T0 and T1 was significantly shorter than that in patients without maxillary protraction appliances. However, none of the changes in cephalometric measurements were correlated with root length.Conclusions:In patients with unilateral cleft lip and palate, the short root length of cleft-adjacent central incisors might be associated with the horizontal position of the root apex. In addition, orthodontic treatment with a maxillary protraction appliance before secondary alveolar bone grafting might be associated with short U1 root length.     

Cephalometric evaluation of patients treated by maxillary anterior segmental distraction: a preliminary report.

OBJECTIVE: The aim of this study was to evaluate the cephalometric results of distraction osteogenesis in patients with premaxillary deficiency. MATERIAL AND METHODS: In this study, an individual tooth-borne distraction device was used for advancement of the maxillary anterior segment. Unilateral or bilateral distraction was performed for 7 patients, according to the specific requirements of the individuals. Cephalometric radiographs were taken before treatment (T0), after distraction (T1), and after consolidation for 8 weeks (T2). RESULTS: Cephalometric analysis revealed that the premaxilla was moved forward and upward and the length of palatal plane increased. CONCLUSION: These alterations improved the soft tissue profile and solved the space deficiency of the maxilla by increasing the arch perimeter.     

Treatment effects of the mandibular anterior repositioning appliance on patients with Class II malocclusion.

The mandibular anterior repositioning appliance (MARA) is a tooth-borne functional appliance for use in patients with Class II malocclusions; it positions the mandible forward into a Class I occlusion. The aim of this study was to investigate the MARA's dental and skeletal effects on anterior, posterior, and vertical changes in 30 Class II patients. The treatment group consisted of 12 boys with an average age of 11.2 years and 18 girls with an average age of 11.3 years. A pretreatment cephalometric radiograph was taken 2 weeks before treatment, and a posttreatment cephalometric radiograph was taken 6 weeks after removal of the MARA, with an average treatment time of 10.7 months. The mean and standard deviation were calculated for each cephalometric variable, and Student t tests were performed to determine the statistical significance of the changes. The results of the study showed that the MARA produced measurable treatment effects on the skeletal and dental elements of the craniofacial complex. These effects included a considerable distalization of the maxillary molar, a measurable forward movement of the mandibular molar and incisor, a significant increase in mandibular length, and an increase in posterior face height. The effects of the MARA treatment were then compared with those of the Herbst and Fr?nkel appliances. The treatment results of the MARA were very similar to those produced by the Herbst appliance but with less headgear effect on the maxilla and less mandibular incisor proclination than observed in the Herbst treatment group.     

Long-term skeletal and dental effects of mandibular symphyseal distraction osteogenesis.

The purpose of this study was to evaluate the effects of mandibular symphyseal distraction osteogenesis using a tooth-borne expansion device. The sample included 20 Hispanic nonsyndromic patients (11 males and 9 females) between 13.5 years and 37.3 years of age. Predistraction (1.5 months before surgery), postdistraction (1 month after surgery), and long-term follow-up (1.3 year after surgery) records included posteroanterior, lateral, and panoramic radiographs and models. Postdistraction radiographic evaluation showed that symphyseal distraction osteogenesis produced insignificant increases in the bicondylar, bigonion, and biantegonion widths; intermolar and, especially, intercanine widths increased significantly and a distraction gap was observed in the symphyseal region. Follow-up model analysis showed the largest width increases between the first molars and second premolars and the smallest width increases between canines and first premolars. The difference between the postdistraction and long-term follow-up width changes was explained by the postdistraction orthodontic effect, which modified the shape of the dental arch. A disproportionate pattern of distraction, characterized by significantly greater dental than skeletal widening, was observed in the second molar and antegonion region. Distraction osteogenesis without presurgical orthodontic treatment produced significant proclination of the mandibular incisors; no proclination was observed in cases with predistraction orthodontic treatment. Dental crowding was resolved by the movement of teeth into the distraction regenerate and concomitant orthodontic treatment. Follow-up radiographs showed transverse skeletal stability of the distraction procedure. We conclude that mandibular symphyseal distraction osteogenesis increased mandibular arch width and partially corrected dental crowding, with a potential for disproportionate distraction patterns and proclination of the mandibular incisors.     

Condylar displacement related to mandibular symphyseal distraction.

This study was undertaken to determine the true nature of condylar displacements associated with mandibular symphyseal distraction osteogenesis. Earlier investigators have assumed that each mandibular half rotated about a point near the center of each condyle as viewed on a submental radiograph. In a 12-patient sample, 10 with tooth-borne symphyseal distraction and 2 with bone-borne symphyseal distraction, it was found that each condyle was laterally displaced in direct relationship to the amount of symphyseal distraction. The rigidity of the distraction appliances and their attachments and the inability of the soft tissues and muscular attachments to cause the mandible to undergo compound bending require this to be the case. Temporomandibular joints appear to be able to accommodate the lateral displacements because symptoms were not introduced, or, if present before therapy, distraction did not exacerbate them.     

Dental stability and radiographic healing patterns after mandibular symphysis widening with distraction osteogenesis

Distraction osteogenesis is the biological process of new bone formation between bone segments that are gradually separated by incremental traction. The purpose of this study was to assess dental stability and radiographic healing patterns following mandibular symphysis widening with distraction osteogenesis (MSDO) in 19 non-syndromic patients (10 males, 9 females: mean age at the time of surgery 20 years 11 months). To evaluate dental stability, 13 landmarks were measured on the study models of all patients and healing patterns were classified for 11 subjects according to healing times on periapical or occlusal radiographs at three time points: pre-distraction (T1), post-distraction (T2), and follow-up (T3; average 1 year 6 months). Paired t-tests were used to evaluate the change between T2-T1, T3-T2, and T3-T1. The results of this study showed that although there was a decrease in expansion during treatment, the total amount of surgical expansion was maintained. Arch length was significantly increased and irregularity was significantly decreased (both P<0.001). There was evidence of mineralization of the distraction gap in 11 patients within 3 weeks of the end of activation. Radiographically, healing patterns for the distraction gap were diverse, but radiopacity increased over time. MSDO is dentally stable and the distracted gap is mineralized with time, indicating that MSDO is an efficient and stable treatment method in subjects with skeletal mandibular transverse deficiency.     

Periodontal changes following distraction osteogenesis in patients with cleft lip and palate: a clinical trial

ObjectivesTo evaluate inflammatory mediator levels and periodontal changes following distraction osteogenesis (DO) in patients with cleft lip and palate (CLP) using mid-maxillary distraction (MMD).Materials and MethodsA total of 20 healthy patients with CLP with Class III malocclusion were included. Segmental forward advancement of the anterior maxilla from the second premolars on both sides using DO was performed. A custom-made, tooth-borne distractor connecting buccal molar segments to the anterior maxilla was used for 7 days with 0.5-mm distraction for the first 2 days and then increased to 1 mm daily until overcorrection. Crevicular interleukin IL-1β and tumor necrosis factor TNF-α levels were measured during distraction. Periodontal clinical parameters and indices were recorded at baseline and 3 and 6 months postoperatively. Soft tissue healing was evaluated histologically at 2 and 4 weeks after distraction.ResultsThe periodontal parameters remained stable during the follow-up periods. Insignificant increases in the level of inflammatory cytokines compared with the control were observed. Histological findings revealed mild inflammatory and structural changes in the gingiva immediately after distraction, whereas regeneration was noticed after 4 weeks.ConclusionsMMD was an effective technique in treating patients with CLP, leading to new bone and soft tissue formation without significant detrimental effect on the periodontium of the adjacent teeth.     

唇腭裂术后面中份畸形经牙支持式牵张器治疗的头影测量评价

目的：运用头影测量评估牙支持式牵张器治疗唇腭裂术后面中部凹陷畸形效果。方法：26例无法采用单纯正颌手术治疗的唇腭裂术后颌面部畸形患者,利用牙支持式牵张器进行骨牵张矫治。牵张前（T1）,牵张后（T2）及8周固定期后（T3）均行头影测量。结果：术创正常愈合,牵张过程顺利,达到预期牵张目的。头影测量分析显示上颌前部得到有效向前、向下移动;腭平面延长。结论：牙支持式牵张器可有效治疗唇腭裂术后上颌骨发育不足及软组织量不足的患者。     

下颌骨正中牵引成骨系统有限元模型的建立

目的:建立使用3种不同牵引器(牙支持式、骨支持式和混合支持式)的下颌骨正中牵引成骨系统的有限元模型。方法:使用人体颌面部标准解剖模型,通过激光扫描,建立下颌骨、牙列和颞下颌关节盘的三维几何模型。描绘出颞下颌关节囊轮廓并生成关节囊几何模型。将下颌骨几何模型和3种牵引器简化几何模型导入有限元建模软件中,建立3种牵引器的下颌骨正中牵引成骨系统的有限元模型。结果:成功建立了使用3种牵引器下,颞下颌关节可自行旋转的下颌骨正中牵引成骨的有限元模型。结论:该模型仿真程度高,接近临床实际,为后续研究下颌骨正中牵引成骨对颞下颌关节的生物力学影响,提供了良好的实验平台。     

Pain and discomfort during the first week of rapid maxillary expansion (RME) using two different RME appliances: A randomized controlled trial

Objectives:To evaluate and compare perceived pain intensity, discomfort, and jaw function impairment during the first week with tooth-borne or tooth-bone–borne rapid maxillary expansion (RME) appliances.Materials and Methods:Fifty-four patients (28 girls and 26 boys) with a mean age of 9.8 years (SD 1.28 years) were randomized into two groups. Group A received a conventional hyrax appliance and group B a hybrid hyrax appliance anchored on mini-implants in the anterior palate. Questionnaires were used to assess pain intensity, discomfort, analgesic consumption, and jaw function impairment on the first and fourth days after RME appliance insertion.Results:Fifty patients answered both questionnaires. Overall median pain on the first day in treatment was 13.0 (range 0–82) and 3.5 (0–78) for groups A and B, respectively, with no significant differences in pain, discomfort, analgesic consumption, or functional jaw impairment between groups. Overall median pain on the fourth day was 9.0 (0–90) and 2.0 (0–71) for groups A and B, respectively, with no significant differences between groups. There were also no significant differences in pain levels within group A, while group B scored significantly lower concerning pain from molars and incisors and tensions from the jaw on day 4 than on the first day in treatment. There was a significant positive correlation between age and pain and discomfort on the fourth day in treatment. No correlations were found between sex and pain and discomfort, analgesic consumption, and jaw function impairment.Conclusions:Both tooth-borne and tooth-bone–borne RME were generally well tolerated by the patients during the first week of treatment.     

Effects of growth on maxillary distraction osteogenesis in cleft lip and palate

PurposeThe objective was to analyze the effects of growth on the long-term result of maxillary distraction osteogenesis (DO) in cleft lip and palate (CLP).Patients and methodsRetrospective study of 24 CLP cases with long-term follow-up operated for maxillary DO using the Polley and Figueroa technique: 10 patients were distracted during growth, while 14 patients were operated after their growth spurt. Preoperative (T0), 6–12 months postoperative (T1), and ≥4 years postoperative (T2) cephalometric radiographs were evaluated. A classical cephalometric analysis was used to assess the treatment stability, and a Procrustes superimposition method was performed to assess local changes in the maxilla and the mandible.ResultsAt T0, the mean age was of 11.9 ± 1.4 years for growing patient, and 17.9 ± 3.5 years for patient treated after their growth spurt (P < 0.001). Between T0 and T1, a greater increase of the SNA was shown in growing patients (P = 0.036), but the relapse was more important between T1 and T2, with a significant decrease of the SNA (P = 0.002) and ANB (P = 0.032) compared to the patients treated after their growth spurt. Although not significant, growing patients showed greater rotations of their palatal plane and mandibular plane.ConclusionsMaxillary DO in CLP does not correct the growth deficit inherent to the pathology. Overcorrection of at least 20% is advised during growth.     

Treatment of mandibular asymmetry by distraction osteogenesis and orthodontics: a report of four cases

Distraction osteogenesis devices followed by hybrid functional appliance therapy and fixed orthodontic appliance therapy were used to correct a variety of maxillofacial skeletal and dental deformities in 4 patients. The patients underwent procedures to lengthen the mandibular ramus and body. Transcutaneous pins were used to activate the distraction devices. After achieving the desired skeletal position, the distraction devices were maintained for 2 to 3 months to allow ossification. Following distraction, functional orthodontic appliance therapy was initiated during growth to correct the cant of the occlusal plane by extrusion of teeth on the affected side for improved facial symmetry. Fixed orthodontic therapy was used for final occlusal adjustments. All patients achieved lengthening of their jaws and substantial improvement in facial symmetry and occlusion. The follow-up period for this group of 4 patients ranged from 18 to 36 months.