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埋伏齿是临床常见病,大多选择拔牙治疗。埋伏尖牙给患者带来美观、功能及心理不良影响。随着正畸技术的日益提高以及口腔颌面外科与正畸科的合作,使绝大多数埋伏牙避免了拔除的厄运。本文报告外科与正畸联合治疗埋伏齿1例,追踪观察其治疗效果。     

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目的探讨正畸与种植体联合治疗下前牙先天缺失伴错畸形的临床效果。方法对2003—2007年在中国医科大学口腔医学院正畸科就诊的15例下切牙缺失伴错畸形的患者行正畸治疗,开辟种植义齿修复间隙,然后行种植义齿修复缺失牙。结果经联合治疗后15例患者均获得正常的覆、覆盖关系和美观效果。共植入25枚种植体,随访时间12～24个月,均稳定无松动。结论正畸与种植体联合应用治疗伴有下切牙先天缺失的错畸形,能够获得满意的治疗效果。     

Associations between orthodontic treatment need and oral health‐related quality of life among young adults: does it depend on how you assess them?

Liu Z, McGrath C, Hägg U. Associations between orthodontic treatment need and oral health‐related quality of life among young adults: does it depend on how you assess them? Community Dent Oral Epidemiol 2011; 39: 137–144. © 2011 John Wiley & Sons A/S Abstract – Objective: To determine the association between orthodontic treatment need (OTN) and oral health‐related quality of life (OHRQoL). Methods: A cross‐sectional study involving 273 young adults seeking orthodontic care. OHRQoL was assessed by the short‐form Oral Health Impact Profile (OHIP‐14) and United Kingdom oral health‐related quality of life measure (OHQoL‐UK). Study casts were assessed for OTN by: Dental Aesthetic Index (DAI), Index of Orthodontic Treatment Need (IOTN)‐Aesthetic Component (IOTN‐AC) and Dental Health Component (IOTN‐DHC) and Index of Complexity, Outcome and Need (ICON). Variations in OHIP‐14 and OHQoL‐UK were determined with respect to OTN, and the magnitude of differences was calculated (effect size: ES). Results: There were significant but weak correlations between occlusal indices scores and OHIP‐14 scores (P < 0.05, r < 0.3) and between occlusal indices scores and OHQoL‐UK scores (P < 0.05, r < 0.4). The magnitude of the statistical difference in OHQoL‐UK scores was moderate to large with respect to OTN (ES: 0.36–0.87) and largest when DHC (ES = 0.87) and ICON (ES = 0.74) were used. The magnitude of the statistical difference in OHIP‐14 scores was relatively lower (ES: 0.21–0.69), but also greatest when DHC and ICON were used to determine OTN (ES 0.69 and 0.50, respectively). Conclusion: Orthodontic treatment need was associated with OHRQoL. The magnitude of the statistical difference between those with and without an orthodontic treatment need was larger when OHRQoL was assessed using OHQoL‐UK compared to OHIP‐14. DHC and ICON were more useful indices in identifying greater differences in OHRQoL with respect to orthodontic treatment need.     

组织工程骨修复牙槽突裂的研究进展

牙槽突裂是伴发于唇腭裂的一种常见的先天性发育缺陷性疾病.为消除牙槽突裂患者的口鼻瘘,使裂隙区以及裂隙两侧的牙齿能正常萌出并能获得良好的牙周附着,这类患者常常需要作二期骨移植.传统的取自患者自身新鲜骨的骨移植修复,虽能较好地修复牙槽突裂,但也存在着诸多弊端:受供区取骨量的限制和骨移植后随着患者的生长和植骨区植入骨的吸收,...     

Root contact during insertion of miniscrews for orthodontic anchorage increases the failure rate: an animal study

OBJECTIVES: Miniscrews and miniplates are increasingly being used for absolute anchorage during orthodontic treatment. However, potential problems of damaging adjacent roots and their consequences during mini-implant placement in the alveolar process have not been clearly described. MATERIALS AND METHODS: Animal experiments were used to evaluate the stability of miniscrews placed with intentional root contact. The root repair was evaluated after screw removal. Seventy-two miniscrews were surgically placed in the mandibular alveolar bone of six adult mongrel dogs with metabolic bone labeling at 3-week intervals. Miniscrews of the experimental group were placed so that they contacted the root of the adjacent teeth, were retained for different time durations, and were then removed. The insertion torque, clinical measurements, removal torque, and histological findings were analyzed. RESULTS: (1) miniscrews contacting the roots showed a significantly higher insertion torque than those without contact; (2) there was a significant difference in the removal torque measurements based on the mobility of miniscrews and the state of root contact; and (3) miniscrews contacting the root were at greater risk of failure. CONCLUSIONS: During placement of miniscrews in the aveolar process, increased failure rates were noticed among those contacting adjacent roots. Failed miniscrews appeared to be surrounded with a greater volume of soft tissue. When more inflammation was present, the adjacent roots seemed to experience more resorption. Nevertheless, the created lesion was repaired with a narrow zone of mineralized tissue deposited on the root surface, which was likely cellular cementum, and was mainly filled with alveolar bone, with the periodontal ligament space being maintained.     

Evaluation on the movement of endosseous titanium implants under continuous orthodontic forces: an experimental study in the dog

Objectives: The purpose of this study was to evaluate the movement of pure titanium implants under different continuous forces in the edentulous alveolar ridge. Material and methods: Four pairs of titanium implants were inserted into the right maxillary and mandibular post‐extraction edentulous ridge of the experimental dog. Three different levels of continuous force (100, 200, and 500 g) were loaded onto three pairs of adjacent implant abutments using a memory Ni–Ti coil spring for up to 6 months and the remaining two implant abutments as the control group received no force. The positions of implant abutments were observed and the distances between the implants abutment at the top, middle and base levels were measured at the 0th, 2nd, 3rd, 6th and 8th month of the follow‐up period. Results: There was no significant change in the distances between adjacent abutments loaded with 100 or 200 g continuous forces throughout the entire study period. However, significantly more movement of implant abutments was noted in the 500 g pair after the 3rd month of loading when compared with the 200 or the 100 g pair (both P<0.001). This change further increased at the 6th month (P<0.001, 0.01, respectively). Moreover, the difference in the measurements at the top, middle and base level indicated that the two adjacent implants moved in a tipping manner in the 500 g pair after 3 and 6 months of loading. Conclusion: The osseointegrated implants remained stable and rigid with a pulling force of 100 and 200 g after 6 months of loading. However, when the force reached 500 g, the implants moved in an inward‐tipping pattern. The results suggested that endosseous titanium implants might not necessarily be rigid anchorages under all circumstances.     

Anatomic site evaluation of the palatal bone for temporary orthodontic anchorage devices

Objectives: The aim of the present study was to assess the micromorphologic characteristics of the palatal bone from an implantologic standpoint.
Materials and Methods: The material consisted of tissue blocks of autopsy material from 22 subjects (18 males, three females) between 18 and 63 years of age. The specimens comprised the anterior median palatal region from 5 to 10 mm behind the incisive foramen. They were prepared in the transversal plane according to ground thin-section technology. The midpalatal area as well as an area of 3 mm bilateral to the midline were assessed, and a classification of quantitative palatal bone availability was developed.
Results: The findings could be divided into three classes: (1) class I palatal bone consists almost of compact bone; (2) class II cortical bone layer on oral and nasal sides of palate, broad compact bone in the suture area (≥3 mm), loose trabecular bone lateral to the suture area; and (3) class III cortical bone on oral and nasal side, thin compact bone in the suture area (<3 mm) and loose-structured trabecular bone lateral to the suture area. In most sections (72.7%), class I characteristics were found (16 subjects). 18.2% of sections were assigned to class II (four subjects) and only 9.1% of sections were assigned to class III (two subjects).
Conclusion: These results document that in most cases a good primary stability of temporary orthodontic anchorage devices should be achieved in the midpalatal and paramedian area of the anterior palate, as the bone quantity available is high.     

Spacing and crowding among African and Caucasian children

OBJECTIVE: To determine spacing and crowding according to ethnic group, gender and dental emergence stage among Tanzanian African and Caucasian children. DESIGN: Cross-sectional epidemiological clinical study. SETTING: A total of 869 African (428 boys, 441 girls) and 706 Caucasian (319 boys, 387 girls) school children, aged 3(1/2)-16 years. MAIN OUTCOME MEASURES: Comparison of spacing and crowding between African and Caucasian children according to gender and dental emergence stage. RESULTS: Spacing was more often found in the maxilla, while crowding was more common in the mandible. Only during the transition of the maxillary permanent front teeth was there significantly more spacing in Caucasians. No gender differences were found. In both samples spacing decreased during later emergence stages. Crowding was more often found in Caucasian children than in African children. In Caucasian children the frequency of crowding increased with advanced emergence stages, while for Africans the trend was not consistent. CONCLUSION: When planning resources for orthodontic treatment for different populations as well as planning treatment for individuals, ethnic background and emergence stage of the dentition need to be considered.     

Low-energy laser stimulates tooth movement velocity via expression of RANK and RANKL

OBJECTIVE: Recent studies have demonstrated that low-energy laser irradiation stimulates bone formation in vitro and in vivo. However, very little is known about the effects of laser irradiation on osteoclastogenesis. The receptor activator of the nuclear factor-kB (RANK) / RANK ligand (RANKL) / osteoprotegerin (OPG) system is essential and sufficient for osteoclastogenesis. The present study was designed to examine the effects of low-energy laser irradiation on expressions of RANK, RANKL, and OPG during experimental tooth movement. DESIGN: To induce experimental tooth movement in rats, 10 g of orthodontic force was applied to the molars. Next, a Ga-Al-As diode laser was used to irradiate the area around the moved tooth and the amount of tooth movement was measured for 7 days. Immunohistochemical staining with RANK, RANKL, and OPG was performed. Real time PCR was also performed to elucidate the expression of RANK in irradiated rat osteoclast precursor cells in vitro. RESULTS: In the irradiation group, the amount of tooth movement was significantly greater than in the non-irradiation group by the end of the experimental period. Cells that showed positive immunoreactions to the primary antibodies of RANKL and RANK were significantly increased in the irradiation group on day 2 and 3, compared with the non-irradiation group. In contrast, the expression of OPG was not changed. Further, RANK expression in osteoclast precursor cells was detected at an early stage (day 2 and 3) in the irradiation group. CONCLUSION: These findings suggest that low-energy laser irradiation stimulates the velocity of tooth movement via induction of RANK and RANKL.     

Temporomandibular joint adaptations following two-phase therapy: an MRI study

Authors – Wadhawan N, Kumar S, Kharbanda OP, Duggal R, Sharma R Aim – To document the alterations within the condyle‐glenoid fossa (C‐GF) complex and the positional changes of the glenoid fossa in the cranium after removable functional appliance therapy and after the completion of fixed appliance therapy. Setting and Sample – The Department of Orthodontics, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi, India. The study sample consisted of 12 growing children (eight girls and four boys) between 10 and 14 years of age with skeletal Class II division 1 malocclusion selected on well defined criteria. Materials and Methods – All patients were treated with either the Twin Block or the Bionator appliance followed by fixed appliances. Mean total treatment duration was 28 months. The changes in and around the C‐GF complex were evaluated using MRI at pre‐treatment stage, after functional appliance therapy and at the completion of fixed mechanotherapy. Results – Forward condylar position within the glenoid fossa and articular disc retrusion with respect to the condylar head were statistically significant after functional appliance therapy. However, the condyles had a relatively concentric position within the glenoid fossa, while the articular disc resumed its pre‐treatment position at the end of the treatment. Linear measurements from the centre of the external auditory meatus to the post‐glenoid spine revealed a 1.3‐mm forward relocation of the post‐glenoid spine along the Frankfurt Horizontal plane. Conclusions – Forward relocation of the C‐GF complex seems to be one of the mechanisms of action of functional appliances, while the internal anatomic arrangement within the temporomandibular joint (TMJ) complex normalizes to its pre‐treatment position.