Cone-beam computerized tomography evaluation of canine retraction using micro implant and conventional anchorage

ObjectiveVarious anchorage techniques have been designed for canine retraction. The aim was to measure and compare the rate of canine retraction with conventional method and micro implant using CBCT.Materials and methodsSample size comprising of 17 subjects were scheduled for extraction of all first premolars. After leveling and aligning, titanium micro implants were placed between the roots of the second premolar and the first molars on right side, in both the arches. Pre and post retraction CBCT scans were taken. Retraction was done using sliding mechanics using stainless steel arch wire.ResultsThe maxillary right canine (micro implant) retracted by 6.75 mm and tipped distally by 9.51° at a rate of 1.05 mm/month while the mandibular right canine retracted by 4.83 mm and tipped distally by 7.88° at a rate of 1.13 mm/month. On the left side (conventional) with molar as a source of anchorage, maxillary canine retracted by 6.03 mm and tipped distally by 6.51° at a rate of 1.46 mm/month while the mandibular canine retracted by 5.03 mm and tipped distally by 4.34° at a rate of 1.15 mm/month.ConclusionImplants can serve as a source of anchorage.     

成人骨性Ⅲ类错牙合患者正畸去代偿前后下切牙区牙槽骨形态特征的CBCT研究

目的比较正畸去代偿前后严重的成人骨性Ⅲ类错牙合患者下切牙区牙槽骨形态变化情况。方法对15例接受正畸-正颌联合治疗的严重成人骨性Ⅲ类错牙合患者(男9例,女6例,平均年龄23.6岁),分别在治疗前(T0期)和正颌手术前1个月(T1期)进行CBCT摄片。分别测量正畸前及术前正畸结束时下切牙区牙槽骨形态,包括牙槽骨厚度、牙槽骨附着高度、牙根长度等指标。相关数据采用SPSS15.0统计软件进行配对t检验。结果正畸去代偿前后的比较结果显示:1正畸去代偿以后下切牙唇倾度增大,根尖点距舌侧骨皮质距离变小(P<0.01);2牙槽骨厚度未见明显改变;3唇舌侧牙槽骨附着高度矫治后均有降低,尤其是舌侧牙槽骨附着高度降低显著(P<0.01);4牙根长度测量未见明显改变。当下切牙进行较大范围的唇向倾斜运动时,牙根向舌侧骨皮质靠近,牙槽骨附着高度进一步降低。结论在成人骨性Ⅲ类错牙合的矫治中,由于需要在不良的牙槽骨形态中移动下切牙,必须密切关注其牙周组织状况、牙槽骨形态变化以及牙根与牙槽骨的关系,选择恰当的矫治方案,减少下切牙过度地唇舌向移动,避免不良反应的发生。     

稳定性牙合板治疗颞下颌关节紊乱病患者后髁突骨密度变化的CBCT研究

目的 利用CBCT测量颞下颌关节紊乱病(TMD)患者稳定性牙合板治疗前后髁突骨密度变化,分析稳定性牙合板对髁突改建的影响.方法 纳入40例稳定性牙合板治疗的TMD患者,治疗前后拍摄CBCT.运用MIMICS 21.0软件中Density功能测量髁突皮质骨密度,对髁突前斜面、顶部、后斜面骨密度进行统计学分析.结果 治疗前...     

Radiographic Bone Loss and Its Relation to Patient-Specific Risk Factors,LDL Cholesterol,and Vitamin D: A Cross-Sectional Study

The influence of patient-specific factors such as medical conditions, low-density lipoprotein cholesterol (LDL-C) or levels of 25-hydroxyvitamin D (25OHD) on periodontal diseases is frequently discussed in the literature. Therefore, the aim of this retrospective cross-sectional study was to evaluate potential associations between radiographic bone loss (RBL) and patient-specific risk factors, particularly LDL-C and 25OHD levels. Patients from a dental practice, who received full-mouth cone beam CTs (CBCTs) and blood-sampling in the course of implant treatment planning, were included in this study. RBL was determined at six sites per tooth from CBCT data. LDL-C and 25OHD levels were measured from venous blood samples. Other patient-specific risk factors were assessed based on anamnesis and dental charts. Statistical analysis was performed applying non-parametric procedures (Mann–Whitney U tests, error rates method). Data from 163 patients could be included in the analysis. RBL was significantly higher in male patients, older age groups, smokers, patients with high DMFT (decayed/missing/filled teeth) score, lower number of teeth, and high LDL-C levels (≥160 mg/dL). Furthermore, patients with high 25OHD levels (≥40 ng/mL) exhibited significantly less RBL. In summary, RBL was found to be associated with known patient-specific markers, particularly with age and high LDL-C levels.     

北京地区正常(牙合)青少年上颌骨三维对称性随生长发育变化的研究

目的 对北京地区正常(牙合)青少年面部对称性随生长发育变化进行初步研究,以期从横向和纵向的角度观察上颌骨对称性随年龄的变化.方法 筛选正常(牙合)青少年36人(初始测量年龄为7～11岁),连续观察3年.用CBCT的检测方法,以S-N-Ba平面为正中矢状面(MSP),测量左右面部双侧上颌标志点到正中矢状面距离(14项双侧标志点测量项目).结果 第1次测量,左右侧眶点至正中矢状面距离有显著性差异(P＜0.05),外耳道最上点至正中矢状面距离(Po-MSP)有显著性差异(P＜0.01).第3次测量,Po-MSP(P ＜0.01),左侧颧额缝点至正中矢状面距离(P＜0.05),左右侧测量值有显著性差异.连续3年的研究结果显示,只有骨性外耳道上缘的耳点(Po)随年龄增长有显著性差异(P＜0.05).结论 正常青少年人群的面部呈对称性生长,部分测量值的左右对称性在某一次测量中有显著性差异,但连续观察2年,除耳点外,其余测量值均无显著性差异.     

冲压式上颌窦底提升术同期种植临床分析

目的:探讨上颌后牙区采用冲压式上颌窦底提升术植骨与不植骨同期种植的效果。方法:2001年1月—2007年12月,共完成冲压式上颌窦底提升种植修复病例91例,男35例,女56例,随机分为2组,植骨组47例,植入57颗种植体;不植骨组44例,植入种植体51颗,共植入108颗种植体。上颌窦底剩余牙槽骨高度为5～11mm,提升幅度为2～6mm。平均随访56.8个月。35例患者(41颗种植体)于后期随访中行锥形束CT(CBCT)和根尖片,观察种植体新骨形成量和种植体突出窦底高度,应用SPSS17.0软件包对数据进行方差分析和t检验。结果:植骨组7颗种植体脱落,存留率为87.7%;不植骨组3颗种植体脱落,存留率为94.1%。CBCT扫描显示,提升幅度为2～4mm时,植骨组新骨形成高度为(2.7±1.3)mm,不植骨组为(2.4±1.5)mm,2组间无统计学差异;提升幅度为4～6mm时,植骨组新骨形成高度为(3.5±1.3)mm,不植骨组为(1.3±0.4)mm,植骨组比不植骨组新骨形成高度显著增加。结论:在上颌后牙缺失区采用冲压式上颌窦底提升、不植骨同期种植是安全可行的,植骨材料对于促进新骨形成并非必须,然而提升幅度较大时,植骨能获得更多的骨量。     

Cone beam computed tomography findings in temporomandibular joint of chronic qat chewers: Dimensional and osteoarthritic changes

The social habit of chewing qat (also known as khat) is widely practised in East Africa and the Arabian Peninsula. It has been linked with various oro-facial conditions, including temporomandibular joint disorders (TMD). This cross-sectional, comparative study sought to investigate the effects of qat chewing on temporomandibular joint (TMJ), using cone beam computed tomography (CBCT). A total of 85 Yemeni males were included. The participants were divided into two groups: Qat chewers (QC; n = 41) and non-qat chewers (NQC; n = 44). Relevant data were obtained using a structured questionnaire and standardised clinical examination. Additionally, CBCT images of the TMJs were obtained, and then, osteoarthritic changes and TMJ dimensions were analysed. SPSS 21 was used for statistical analyses, with a significant level was set at 0.05. Compared to NQC, a significantly higher proportion of QC presented with clinical signs of TMDs. The qualitative CBCT findings revealed significantly higher osteoarthritic changes in QC than in NQC: osteophyte (51.2% vs 22.7%; P = .008), subcortical sclerosis (48.8% vs 27.3%; P = .047), articular surface flattening (46.3% vs 6.8%; P = .009) and subcortical cysts (43.9% vs 4.5%; P < .001). However, CBCT quantitative findings (condylar dimensions) did not show significant differences between the two groups. The chewing side of the QC group showed slightly more changes compared to the non-chewing side. The results demonstrate that qat chewing has detrimental effects on TMJ manifested mainly as osteoarthritic changes. Further large-scale studies are recommended.     

Cone-beam Computed Tomographic–based Assessment of Filled C-shaped Canals: Artifact Expression of Cone-beam Computed Tomography as Opposed to Micro–computed Tomography and Nano–computed Tomography

IntroductionThe present study investigated the assessment of root canal fillings in a series of cone-beam computed tomographic (CBCT) images obtained from endodontically treated mandibular molars with C-shaped canals.MethodsClinically comparable high (HR) and normal (NR) resolution protocols were selected in 3D Accuitomo 170 (J Morita Corporation, Kyoto, Japan), NewTom VGi evo (Cefla QR Verona, Verona, Italy), ProMax 3D Max (Pro; Planmeca, Helsinki, Finland), and Pax-i3D Green Premium (Pax; Vatech, Gyeonggi, South Korea). Micro–computed tomographic and nano–computed tomographic images were considered as the reference standard. The set of images was evaluated according to beam hardening artifact patterns (dark streaks, hypodense areas, and volume distortion).ResultsRegarding dark streaks, the Fleiss kappa test showed that Pax HR and NR and Pro HR images showed the highest artifact expression. Hypodense areas were detected in 100% and 99.1% of the images obtained using Pax HR and NR, respectively. Kappa tests showed highest distortion for images derived from the Pax and Pro CBCT devices. Root canal filling assessment was considered appropriate in 100% of the 3D Accuitomo 170 HR, NewTom VGi evo NR, micro–computed tomographic, and nano–computed tomographic images.ConclusionsThe present study confirms the large variability in CBCT-derived artifact expression. Highlighting the increased artifact expression for particular CBCT systems, it may be concluded that for diagnosis of endodontically filled molars with C-shaped canals, the choice of CBCT unit and protocol is essential.     

Five-year survival rates for implants placed using digitally-designed static surgical guides: a systematic review

Digitally-designed static surgical guides provide an acceptable level of accuracy and predictability for the placement of dental implants. However, to our knowledge, few published studies have compared the long-term survival of implants placed in this way with those placed using other methods. A systematic search of electronic databases using a population, intervention, comparison, and outcome (PICO) framework was conducted of Medline and EMBASE, as well as grey literature and hand searches, to obtain all relevant work pertaining to the survival of dental implants placed by guided surgery. The studies were required to have at least 10 patients with a follow up of at least five years. A total of 621 titles were screened. Four studies met the inclusion criteria for quantitative analysis, and they all reported the exclusive use of Nobel Biocare implants and the NobelGuide system (Nobel Biocare Services). Cumulative survival rates ranged from 94.5% to 100% over five years. The survival rates of implants placed using digitally-designed static surgical guides are comparable to the estimated overall survival rate (95.6% over five years), despite the complex nature of the treatments done with guided surgery. Clinicians who do these operations should, however, have the experience and ability to revert to conventional freehand techniques if complications arise.