Histomorphometric Evaluation of Cortical Bone Thickness Surrounding Miniscrew for Orthodontic Anchorage

Background: Recently, the use of miniscrews as an anchorage device has become a routine approach in the orthodontic field. However, there is no report that has analyzed the healing process of the miniscrew, such as the thickness of the cortical bone, in the past. Purpose: In the present study, to histologically assess the healing process of the osseous tissue surrounding miniscrews used as an orthodontic anchorage, the change in the thickness of the cortical bone was analyzed after 3, 6, and 12 weeks after the placement. Furthermore, the change in the bone‐implant contact in different regions of the miniscrew during the initial healing period was also investigated. Materials and Methods: Ninety‐six miniscrews were placed in eight beagle dogs. After 3, 6, and 12 weeks of healing, a force of 200–300 g was applied to the force‐applied groups for 12 weeks. Non‐forced groups remained in the jaw without force application. Results: In the non‐forced groups, a significant amount of cortical bone was formed at the head of the miniscrew at the initial stage of the healing process in the maxilla. However, less cortical bone formation was observed in the mandible. After the force application, increased bone formation was observed within 1 mm of the miniscrew compared to other regions in both jaws. In the mandible, significantly less cortical bone was observed 3 and 6 weeks after the force application. Bone‐implant contact revealed that the osseous tissue surrounding the miniscrew matured from the apex toward the head of the miniscrew. Conclusion: We suggest that this sufficient amount of cortical bone at the initial stage of healing enables the immediate loading in miniscrews to resist against orthodontic force. Furthermore, less amount of cortical bone formed at the head of the miniscrew may be one reason for the higher failure rate in the mandible.     

Pediatric patients' orthodontic treatment need, quality of life, and smiling patterns -- an analysis of patient, parent, and provider responses

Objectives: The objectives of this study is to explore the relationship between pediatric patients' orthodontic treatment need, the patients' assessments of their smile‐related quality of life (QoL), their parents' proxy assessment of their child's QoL and own assessments of their child's smile, and the patients' objectively assessed smiling patterns. Methods: Survey data were collected from 102 patients (53 boys/49 girls; age range: 9–13 years) and their parents. Orthodontic treatment need was assessed with the Index of Complexity, Outcome, and Need (ICON). Smiling patterns were determined by videotaping patients' smiles while they watched a cartoon. Thirty predetermined sections of these tapes were then assessed by two independent raters to measure the patients' smiling patterns. Results: The aesthetic component and total ICON scores correlated with the patients' smile‐related QoL (r = 0.25; P = 0.014/r = 0.23; P = 0.024), parental proxy assessments of the child's smile‐related QoL (r = 0.29; P = 0.004/r = 0.26; P = 0.009), the parents' own assessments of their child's smile (r = 0.32; P = 0.002/r = 0.29; P = 0.005), and the number of negative adjectives chosen by the parents to describe their child's smile (r = 0.32; P = 0.002/r = 0.30; P = 0.004). Although the smiling patterns were correlated with the patients' smile‐related QoL responses (height of smile: r = 0.29; P = 0.005/number of teeth shown: r = 0.30; P = 0.004), the ICON scores were not correlated with the patients' smiling patterns. Conclusions: Objectively assessed orthodontic treatment need correlates with the patients' and parents' assessments of the child's smile‐related QoL scores. However, while objective smiling patterns are related with the patients' smile‐related QoL, they are not correlated with the patients' orthodontic treatment need.     

颌骨骨折正畸治疗与手术治疗的对比研究

目的：对比正畸治疗与手术治疗颌骨骨折的临床疗效。方法：将5年来我院收治的颌骨骨折病例依据治疗方法分为正畸治疗组和手术治疗组。正畸治疗组中上颌骨骨折病例采用上颌螺旋缩弓器治疗,其中部分患者配合前方牵引治疗,下颌骨骨折及髁突骨折病例采用全口固定矫治器配合颌间牵引治疗;手术治疗组采用钛板内固定、部分配合牙弓夹板及牵引治疗。结果：全部病例颌骨骨折均达到一期愈合,两种治疗方法均有一定的局限性。手术治疗损伤大,费用高,副作用多,咬合关系不能保证。结论：用正畸矫治器治疗颌骨骨折,能弥补手术治疗的不足,丰富了临床治疗手段,治疗后关节、肌肉及咬合功能的形态学及功能恢复方面更为协调。     

成人严重骨性Ⅲ类错[牙合]牙颌补偿的研究

目的研究成人严重骨性Ⅲ类错[牙合]矢状和垂直向不调对牙颌代偿的影响。方法选择需接受正颌手术的严重骨性Ⅲ类错[牙合]患者93例,ANB〈-3°。在垂直向不调的研究中根据下颌平面角的大小将患者分为低角（16例）、均角（50例）及高角（27例）三组。通过X线头影测量的方法对颌骨矢向不调与牙[牙合]测量项目做相关性分析。选择SN／AB角与SN／U1角、SN／L1角、SN／OP角对不同垂直向的牙[牙合]代偿进行线性回归分析研究。结果在矢状向与牙[牙合]的相关性分析中,SN／AB与SN／L1的相关性最高（r=0．61）。回归分析表明,SN／AB每改变1°,低角组SN／U1改变0．11°、SN／L1改变0．51°、SN／OP改变0．11°,均角组分别为0．14°、0．40°、0．18°,高角组分别为0．50°、0．95°、0．19°。结论颌骨矢状向和垂直向不调越严重,上切牙代偿性唇倾越多,下切牙代偿性舌倾越多,[牙合]平面代偿性减小越多。     

Prevention of white spot lesions in orthodontic practice: a contemporary review

The development of white spot demineralization associated with fixed appliance orthodontic treatment is a significant clinical problem. Both established and experimental methods for prevention of such lesions in day-to-day clinical practice are presented and discussed.     

Orthodontic movement after periodontal regeneration of class II furcation: a pilot study in dogs

PURPOSE: The effect of orthodontic movement on the periodontal tissues of maxillary second pre-molars, after regenerative treatment for class II furcations, was evaluated in four mongrel dogs. MATERIAL AND METHODS: Class II furcation lesions were created. After 75 days they were treated with bovine bone mineral matrix and guided tissue regeneration with absorbable membrane. After 2 months of daily plaque control, each of the dog's furcation pre-molars was randomly assigned to a test or control group. Orthodontic appliances were placed on both sides of the maxilla using third pre-molars and canines as anchorages. In the test group, bodily orthodontic movement of the second pre-molars was performed in the mesial direction for 3 months while control pre-molars remained unmoved. The dogs were sacrificed for histometric and histologic analyses. RESULTS: There were no statistically significant differences between the two groups in total bone and biomaterial areas or linear extension of periodontal regeneration on the radicular surfaces. In the test group, however, there was a tendency to a greater quantity of bone and a lesser quantity of biomaterial. CONCLUSION: The orthodontic movement was not pre-judicial to the results obtained with the regenerative periodontal treatment.     

不同加载条件下国产微螺钉种植体的支抗稳定性及组织学表现

目的：研究不同载荷下微型种植体的稳定性及种植体骨界面组织学表现,为其成功应用于临床提供理论依据。方法：将微型螺钉种植体（长度7 mm,直径1.4 mm）植入兔的胫骨,共植入种植体120枚。将其分成4组,每组30枚。在种植体植入后即刻分别对种植体施加0、150、300及450 g的载荷,加载时间为20周。加载结束后检查种植体是否发生移位、松动和脱落,同时观察种植体骨结合界面组织学表现。 结果： 所有种植体均保持稳定,未发生松动和脱落。其中,450 g组加载前后位移减小了0.60 mm（P<0.05）,而其他力值组加载前后位移也有所减小,0 g组,0.09 mm;150 g组,0.20 mm; 300 g组,0.16 mm,差异均无统计学意义（P>0.05）。组织学观察,0 g组和150 g组种植体骨结合界面主要发生在骨皮质区,300 g组种植体骨结合界面明显增宽,450 g种植体骨结合界面进一步增宽,几乎发生在种植体全长。结论：种植体在一定载荷范围下可以保持稳定,当载荷达到一定程度,种植体可以发生位移。随着载荷的增加,种植体与骨结合程度亦加强。     

PBL教学方法在口腔正畸本科课间实习教学中的应用

目的：探索口腔正畸本科课问实习教学方法的新模式。方法：将60名学生随机分为PBL教学组和传统教学组,通过试卷考核、问卷调查及课后讨论的方式进行评估。结果：PBL教学组学生在在分析问题和解决问题等方面的能力明显优于传统教学组。结论：PBL教学法能提高学生的学习兴趣并增加学生对内容的深入理解,值得在正畸课间实习课中推广。