Skeletal and dental stability of segmental distraction of the anterior mandibular alveolar process. A 2-year follow-up

33 patients (27 females; 6 males) were retrospectively analysed for skeletal and dental relapse before distraction osteogenesis (DOG) of the mandibular anterior alveolar process at T1 (17.0 days), after DOG at T2 (mean 6.5 days), at T3 (mean 24.4 days), and at T4 (mean 2.0 years). Lateral cephalograms were traced by hand, digitized, superimposed, and evaluated. Skeletal correction (T3-T1) was mainly achieved through the distraction of the anterior alveolar segment in a rotational manner where the incisors were more proclined. The horizontal backward relapse (T4-T3) measured -0.8mm or 19.0% at point B (p<0.001) and -1.6mm or 25.0% at incision inferior (p<0.001). Age, gender, amount and type (rotational versus translational) of advancement were not correlated with the amount of relapse. High angle patients (NL/ML'; p<0.01) and patients with large gonial angle (p<0.05) showed significantly smaller relapse rates at point B. Overcorrection of the overjet achieved by the distraction was seen in a third of the patients and could be a reason for relapse. Considering the amount of skeletal relapse the DOG could be an alternative to bilateral sagittal split osteotomy for mandibular advancement in selected cases.     

Soft tissue stability after segmental distraction of the anterior mandibular alveolar process: a 5.5 year follow-up

Soft tissue changes were analysed retrospectively in 17 patients following distraction osteogenesis (DO) of the mandibular anterior alveolar process. Lateral cephalograms were traced by hand, digitized, superimposed, and evaluated at T1 (17.0 days), after DO at T2 (mean 6.5 days), at T3 (mean 24.4 days), at T4 (mean 2.0 years), and at T5 (mean 5.5 years). Statistical analysis was carried out using Kolmogorov–Smirnov test, paired t-test, Pearson's correlation coefficient, and linear backward regression analysis. 5.5 years postoperatively, the net effect for the soft tissue at point B′ was 88% of the advancement at point B while the lower lip (labrale inferior) followed the advancement of incision inferior to 24%. Increased preoperative age was correlated (p < 0.05) with more horizontal backward movement (T5–T3) for labrale inferior and pogonion′. Higher NL/ML′ angles were significantly correlated (p < 0.05) to smaller horizontal soft tissue change at labrale inferior (T5–T3). The amount of advancement at point B was significantly correlated with an upward movement (T5–T3) of labrale inferior (p < 0.01) and stomion inferior (p < 0.05). It can be concluded that further change in soft tissues occurred between 2.0 and 5.5 years postoperatively. The physiological process of ageing and loss of soft tissue elasticity should be considered as possible reasons.     

Skeletal and dental stability of segmental distraction of the anterior mandibular alveolar process. A 5.5-year follow-up

17 patients (14 female; 3 male) were analysed retrospectively for skeletal and dental relapse before distraction osteogenesis (DO) of the mandibular anterior alveolar process at T1 (17.0 days), after DO at T2 (mean 6.5 days), at T3 (mean 24.4 days), at T4 (mean 2.0 years), and at T5 (mean 5.5 years). Lateral cephalograms were traced by hand, digitized, superimposed, and evaluated. Skeletal correction (T5–T1) was mainly achieved through the distraction of the anterior alveolar segment in a rotational manner where the incisors were more proclined. The horizontal backward relapse (T5–T3) measured ?0.3 mm or 8.3% at point B (non-significant) and ?1.8 mm or 29.0% at incision inferior (p < 0.01). Age, gender, amount and type (rotational vs. translational) of advancement were not correlated with the amount of relapse. High angle patients (NL/ML′; p < 0.01) showed significant smaller relapse rates at point B. Overcorrection of the overjet achieved by the distraction could be a reason for dental relapse. Considering the amount of long-term skeletal relapse the DO could be an alternative to bilateral sagittal split osteotomy for mandibular advancement in selected cases.     

Neurosensory and functional evaluation in distraction osteogenesis of the anterior mandibular alveolar process

Neurosensory status and craniomandibular function of 19 patients (mean age 35.2 years, range 17.8–58.8 years) treated by combined surgical orthodontic treatment with distraction osteogenesis of the mandibular anterior alveolar process (DO group) was compared with that in 41 orthodontically treated patients (mean age 22.9 years, range 15.1–49.0 years; control group). Clinical examination took place on average 5.9 years (DO group) and 5.4 years (control group) after treatment ended. Neurosensory status was determined by two-point discrimination (2-pd) and the pointed and blunt test. Lateral cephalograms evaluated advancement of the mandibular alveolar process and possible relapse. There was no significant difference in craniomandibular function and neurosensory status between the groups. Age was significantly correlated with 2-pd at the lips (DO: p = 0.01, R = 0.575; control group: p = 0.039, R = 0.324) and chin (DO: p = 0.029, R = 0.501; control group: p = 0.008, R = 0.410). Younger patients had smaller 2-pd values. Gender, age, the amount of advancement, and relapse at point B or incision inferior show no correlation with craniomandibular function and neurosensory impairment. DO of the mandibular anterior alveolar process is a valuable and safe method with minor side effects regarding neurosensory impairment.     

Segmental distraction osteogenesis of the anterior alveolar process.

PURPOSE: This article describes a nonextraction therapy for patients with anterior tooth crowding in the mandible or with an unfavorable relation between the anterior dentoalveolar area and the skeletal base. The method involves the gradual repositioning of the dentate segment by use of distraction osteogenesis. PATIENTS AND METHODS: The method was applied in 25 patients. Indications comprised skeletal Class II patients with crowding, Class I patients with crowding, and Class III patients requiring decompensation before orthognathic surgery. A special hinge-joint bone plate was developed to allow the rotation of the anterior bone segment into the desired position. The gradual repositioning was achieved with orthodontic appliances. RESULTS: The procedure was successful in all patients. The typical advancement at the incisal edge was 2 to 5 mm. CONCLUSION: This method represents a new approach for nonextraction therapy in the mandible. It requires no soft or hard tissue grafting and results in favorable tissue conditions at the distraction site.     

Soft tissue profile changes after maxillary advancement with distraction osteogenesis by use of a rigid external distraction device: a 1-year follow-up.

PURPOSE: This study was conducted to evaluate the soft tissue profile changes after maxillary advancement with distraction osteogenesis (DO). PATIENTS AND METHODS: Sixteen subjects underwent maxillary advancement with rigid external distraction after a high Le Fort I osteotomy. There were 11 male and 5 female patients, ages 5.2 to 25.7 years. The subjects included 9 with unilateral cleft lip and palate (UCLP), 4 with bilateral CLP, 2 with facial clefts and bilateral CLP, and 1 with cleft palate. Pretreatment and posttreatment lateral cephalograms were compared to evaluate the changes in soft tissue profile. A line 7 degrees below the SN plane was used as the horizontal coordinate, and a perpendicular line through Sella was used as the vertical coordinate in an XY coordinate system. RESULTS: The preoperative facial concavity (N'SnPg') was reduced by 15.59 degrees, and the nasal tip moved 3.75 mm forward and 2.05 mm upward. These changes were positively correlated with the change of ANS position. The soft-tissue-to-hard-tissue ratio was 0.53:1 for nasal tip and ANS. The ratio was negatively correlated with the age of the patient. The ratio of soft tissue A point to skeletal A point was 0.96:1 and for the incisal edge to vermilion border of the upper lip it was 0.8:1. The soft tissue B point and Pg did not change significantly with maxillary distraction. However, the nasolabial angle increased by 4.96 degrees, the upper lip curvature flattened by 0.65 mm, and the lower lip curvature was accentuated by 0.89 mm after distraction. The amount of upper incisal exposure increased from 1.1 to 5.01 mm in the rest position. CONCLUSION: Maxillary DO improved the soft tissue profile by increasing nasal projection, normalizing the nasolabial angle, and making the upper lip more prominent. More upper anterior tooth show in the rest position was obtained, but the upper lip length did not change. The concave facial profile became convex, with improved facial balance and aesthetics.     

Preprosthetic mandibular vestibuloplasty with split-skin graft. A 2-year follow-up study

17 patients with lower denture malfunction problems related to insufficient residual ridges had a vestibuloplasty with split-skin graft performed in the mandible under local analgesia on an out-patient basis. The patients were followed-up for 2 years and records of vestibular extension showed a maximum of relapse at the 1-month control (24%). Most of the lost extension was regained at the 6-month check, and the 2-year outcome was 92% of the surgically-created vestibular sulcus extension as a mean value of records obtained at the midline and canine regions. A comparison with a previous study on buccal mucosal graft vestibuloplasty led to the conclusion that free grafts of skin and buccal mucosa prevent a relapse equally well under the same circumstances. 13 patients were satisfied with the improvement achieved, 3 reported fair, and 1 was dissatisfied with the result of the operation. The split-skin graft underwent a change of appearance in 5 cases interpreted as a skin graft candidosis. Indication of this condition accelerating the residual ridge resorption is discussed.     

Innovation in anterior mandibular alveolar distraction osteogenesis: Introduction of a new bone-borne distraction device and first clinical results

Segmental distraction osteogenesis of the anterior mandibular alveolar process (frontblock) is a sufficient method to avoid extractions in patients with dental crowding and to decompensate retroalveolism. Up to now dental-borne devices were used, but limitate the indications for front-block distraction.A new bone-borne distraction device for mandibular alveolar front-block movement is introduced in this study. The distractor allows sufficient segmental transport without loading on the teeth. Clinical evaluations of 7 patients have been performed including the feasibility and predictability of the distraction, postoperative pain and patients’ discomfort. The results indicate that this technique is a promising strategy in the correction of dental crowding, correcting the curve of Spee and to decompensate mandibular retroalveolism even in patients with impaired periodontal health and a thin mandibular symphysis.     

Soft tissue to hard tissue advancement ratios for mandibular elongation using distraction osteogenesis in children

Distraction osteogenesis is extensively used for the elongation of hypoplastic mandibles in children, yet the soft tissue profile response to this is not well understood. The pre- and posttreatment lateral cephalometric radiographs of 27 pediatric patients who underwent bilateral mandibular elongation using distraction osteogenesis were analyzed retrospectively to correlate horizontal soft tissue advancement with horizontal underlying bone advancement at B point and pogonion. Horizontal advancement (in millimeters) of bone and overlying soft tissue at these points was collected from the radiographs of each patient, and linear regression analysis was performed to determine the relationship of hard to soft tissue horizontal advancement at these points. A 1:0.90 mean ratio of bone to soft tissue advancement was observed at B point/labiomental sulcus and at pogonion/soft tissue pogonion (linear regression analysis demonstrated slopes [beta1 values] of 0.94 and 0.92, respectively). These ratios were consistent throughout the sample population and are highly predictive of the soft tissue response that can be anticipated. Magnitude of advancement, age, and sex of the patient had no effect on these ratios in our population. This study assists with our understanding of the soft tissue response that accompanies bony elongation during distraction osteogenesis which will allow us to more effectively treatment plan the orthodontic and surgical intervention that will optimize the patients' functional and esthetic outcome.     

The form of the mandibular anterior lingual alveolar process in partially edentulous patients

One hundred adult patients needing a Class I mandibular removable partial denture were selected to determine the incidence and prevalence of the form of the mandibular anterior lingual alveolar process.The processes ranged between 2 and 22 mm in height and from 37 ° to 125 ° angulations in relation to the occlusal plane. Shapes were found to be sloped (45), vertical (38), and undercut (17).The large variety of sizes and shapes of the lingual alveolar process stresses the importance of a precise impression technique to accurately register the anterior lingual alveolar process. Instructions to the dental laboratory for the design of the proper major connector for each specific situation will improve the quality of the removable partial denture service to the patient.     

Mandibular distraction osteogenesis in an adult with severe mandibular retrognathia with arthrosis deformity: A 10-year follow-up

The objectives of this case report are to show how to select the treatment plan for severe mandibular retrognathia and to show the long-term retention follow-up.An adult female with severe retrognathia that might have been caused by arthrosis deformity of the mandibular condyles, was treated with distraction osteogenesis (DO). After presurgical orthodontic treatment, DO was performed to lengthen the retruded mandible. Le Fort I osteotomy and genioplasty were performed to establish functional occlusion and correct her long face, after 5 months of DO. After postsurgical orthodontic treatment, the patient's occlusion had improved markedly, and she exhibited significant aesthetic improvement. Her profile and acceptable occlusion remained stable after 10 years of retention.     

The mandibular bone mineral content in relation to vestibulolingual sulcoplasty. A 2-year follow-up

The bone mineral content (BMC) in mandibles can now be measured in vivo with high precision by a specially constructed dual-photon scanner. This study analyzed, over a 2-year period, the BMC loss of endentulous mandibles in a group of young and older women after vestibulolingual sulcoplasty with free skin grafts, and its relationship to the initial mandibular BMC and the age-related mandibular BMC loss. BMC in the denture-wearing site and the standard site of the mandible was measured by this method. A significant negative relationship was found between the initial BMC values in the standard site and the BMC loss (in percent) in the denture-wearing site in both age groups, and a significant positive relationship between the BMC loss (in percent) in the two sites of the mandible in the elder group. The rate of residual ridge reduction may be predicted from the initial mandibular BMC value and seems to be dependent on the age-related mandibular BMC loss.     

A nonpigmented melanoblastoma of the mandibular alveolar process]

A 64-year-old male patient consulted a doctor for a tumor-like formation in the left submandibular area. The dentist detected ulceration of the alveolar process from the V to the VII tooth. Histological examination diagnosed pigment-free melanoblastoma, a tumor extremely rare in the oral cavity; the prognosis in such a tumor is much worse than in skin melanomas. This case confirms a viewpoint that tumors in the oral cavity are difficult to diagnose and they are usually diagnosed after they manifest themselves by metastases.     

Correction of mandibular dentoalveolar retrusion by anterior segmental advancement.

Mandibular anterior segmental advancement offers an alternative mode of management for certain patients with Class II dentoalveolar malocclusion. The procedure is ideally indicted in paradoxical occlusal situations wherein Class II malocclusion is associated with a prognathic profile or when total body advancement would produce an unacceptable occlusion or profile. Arch expansion and augmentation genioplasty may be achieved by tailoring the surgical approach. Complications were minimal in the cases presented. Since arch lengthening results, the potential food table is increased, necessitating either fixed or removeable prosthetic care.     

三焦点牵引成骨下颌骨缺损重建的实验研究

目的探讨采用内置式三焦点牵引器在犬下颌骨骨段缺损功能重建中牵引成骨的特点、规律。方法使用内置式三焦点牵引器对4只成年犬下颌骨骨段缺损进行牵引成骨重建。制作3cm下颌骨缺损区,同期植入内置式三焦点牵引器。牵引间歇期8天,牵引速度0.5mm×2次/天,稳定期3个月。结果下颌骨牵引成骨约30mm,牵引成骨过程中无感染、成骨不良等并发症。牵引完成后第3个月X线片、组织学观察及扫描电镜观察均可见新生骨的形成,新生骨的形态、组织结构接近正常下颌骨。结论三焦点牵引成骨技术重建的颌骨形态、组织结构和功能接近正常颌骨,牵引成骨区和压力成骨区局部应用rh-BMP2可以促进新骨的形成及钙化。