Task Group for Orthodontics Report.

Abstract

The UK Specialist Review Group of the General Dental Council's Education Committee has been charged with taking forward the recommendations in the Chief Dental Officer's report 'UK Specialist Dental Training'. The Specialist Review Group has, in turn, established a number of specialty task groups. This report is from the Task Group for Orthodontics. It was submitted in May 1996.     

An assessment of conventional and self-ligating brackets in Class I maxillary constriction patients

Objective:To evaluate two different treatment systems with regard to incisor position, transverse dimension changes in maxillary arch, changes in maxillary molar inclinations, clinical periodontal parameters, and pain intensity in patients with a Class I malocclusion.Materials and Methods:Seventeen patients (with a mean age of 14.5 years) underwent orthodontic treatment with the Roth prescribed edgewise bracket systems after expanding the maxillary arch with a quad-helix appliance, and 16 patients (with a mean age of 14.8 years) underwent orthodontic treatment with the Damon 3MX bracket system. Each subject''s lateral cephalometric and posteroanterior radiographs and dental casts were obtained at the beginning of the treatment and after debonding. In addition to these, the periodontal index and pain scores were taken.Results:Cephalometric data showed that in both treatment systems, overjet value decreased and maxillary and mandibular incisors proclined. Posteroanterior measurements demonstrated a greater increase in the maxillary molar inclination in the Damon group. Significant increase of maxillary intercanine, interpremolar, and intermolar widths was shown in both systems. Periodontal index and pain score changes between different observation periods were the same.Conclusions:The conventional and Damon systems were found similar with regard to the incisor position, transverse dimension changes in maxillary arch, clinical periodontal parameters, and pain intensity. The only significant difference was that the Damon system inclined the maxillary molars more buccally than the conventional group.     

Damon自锁托槽对安氏I类错（牙合）畸形矫治前后牙弓宽度的变化研究

目的：通过测量牙弓宽度变化探讨Damon自锁托槽矫治安氏I类错(牙合)畸形的作用机制及疗效。方法：21例处于生长发育期的青少年安氏I类患者,采用Damon自锁托槽进行非拔牙矫治,治疗前后进行头影测量和牙弓宽度测量,分析牙弓宽度的变化特征。结果：矫治后患者牙列拥挤均解除,上、下颌牙弓宽度WU4、WU5、WU6、WL3、WL4、WL5、WL6在治疗后均明显增加(P<0.05)。上、下颌前牙治疗后唇倾度增加,UI-NA、LI-MP、LI-NB治疗前后差异均有统计学意义(P<0.05)。结论：Damon自锁托槽对于治疗安氏I类非拔牙矫治有特殊的疗效,可通过增加患者的牙弓宽度解除牙列拥挤,从而达到非拔牙矫治的效果。     

Damon拔牙与非拔牙矫治前后牙弓宽度变化的研究

目的：比较分析采用Damon矫治技术对牙列拥挤病例进行拔牙与非拔牙矫治的牙弓形态变化。方法：15例中度牙列拥挤病例,使用Damon3矫治器进行非拔牙矫治;15例重度牙列拥挤病例,使用Damon3矫治器进行拔牙矫治。对治疗前后的记存模型进行测量分析,讨论牙弓宽度改变特点。结果：采用Damon矫治技术矫治牙列拥挤的拔牙与非拔牙病例均可取得较好的效果,拔牙组上、下颌尖牙间宽度增大,有统计学意义;非拔牙组上、下颌前磨牙宽度以及上颌第一磨牙间宽度增大,有统计学意义。结论：拔牙组牙弓宽度改变主要与牙齿移动方向有关,非拔牙组牙弓宽度改变与拥挤存在部位以及拥挤程度有关。     

Self‐ligating brackets and treatment efficiency

A number of laboratory studies have shown very low levels of archwire friction for self‐ligating brackets when compared to conventional ligation methods. However, justifiable reservations have been expressed as to the in vivo relevance of these findings. This study was designed to compare treatment efficiency with conventional fully programmed brackets and Damon SL self‐ligating brackets. Thirty consecutively finished cases treated by the author with Damon SL brackets were compared with 30 matched cases treated by the author with conventional brackets. Parallel studies quantified the incidence of technical problems with Damon SL brackets and with conventional ligatures and also the chairside time required for ligation/slide closure and ligature removal/slide opening with these two bracket types. The Damon SL cases required an average of four fewer months and four fewer visits to be treated to an equivalent level of occlusal regularity as measured by the PAR scores.     

Damon技术非拔牙矫治牙列拥挤患者的牙弓形态变化

目的探讨采用Damon技术对牙列拥挤患者进行非拔牙矫治的牙弓形态变化。方法 15例中度牙列拥挤患者,使用DamonⅢ矫治器进行非拔牙矫治。对治疗前后的记存模型进行测量分析,探讨牙弓形态的变化特点。结果矫治后的牙弓长度和宽度均有显著增加,具体的变化特点与牙列拥挤的程度和部位有关。牙弓宽度增加主要发生在上颌第一前磨牙和下颌第二前磨牙区。结论采用Damon技术非拔牙矫治牙列拥挤患者,牙弓形态改变主要是前磨牙区宽度及牙弓长度增加。     

Maxillary arch width and buccal corridor changes with Damon and conventional brackets: A retrospective analysis

Objective:To evaluate the effect of Damon self-ligating and conventional bracket systems on buccal corridor widths and areas.Materials and Methods:A retrospective sample of consecutively treated patients using either conventional (CG, n  =  45) or Damon self-ligating (SL, n  =  39) brackets was analyzed to determine any differences in buccal corridor widths and areas both within and between groups. Pretreatment and posttreatment frontal photographs were transferred to Photoshop CC, standardized using intercanthal width, and linear and area measurements were performed with tools in Photoshop CC. Ratios were then calculated for statistical analysis. Relationships between arch widths and buccal corridors were also examined.Results:There were no significant differences in the posttreatment intercanine or intermolar widths either within or between the CG and SL groups. There were no significant differences in any buccal corridor width or area measurement either within or between the CG and SL groups. There were strong correlations with the intercanine width and the corresponding buccal corridor smile width measurements. There was an inverse correlation with the buccal corridor area in relation to the canine and the total smile width.Conclusions:It is likely that posttreatment increases in arch width can be seen in patients treated with either a conventional bracket system or the Damon system. It is highly unlikely that there is any significant difference in buccal corridor width or area in patients treated with the Damon self-ligating system or a conventional bracket system.     

非减数治疗中不同托槽对牙弓三维方向的影响

目的:探讨非减数治疗中,传统托槽与Damon自锁托槽系统在三维方向上对牙弓产生的影响差异,为临床提供参考。方法:选择非减数治疗的正畸患者45例,随机分为传统托槽+Cu-NiTi丝组(A组)、Damon 3mx+Cu-NiTi丝组（B组）和传统托槽+NiTi丝组（C组）,各组按相同的弓丝顺序和时间排齐整平牙列。分别测量3组术前（T0）和排齐整平后（T1）牙弓前(a)、中(b)、后段(c)的宽度以及头颅侧位片中U1-SN、U1-PP、L1-MP、U6-PP（mm）、L6-MP（mm）等相关数据,采用SPSS22.0软件包对数据进行统计学分析。结果:通过方差分析和t检验,A、B、C 3组的相关数据在治疗前、后的改变量无显著差异。结论:在轻度拥挤的非减数病例中,Damon系统托槽与传统托槽对牙弓在三维方向上的影响无显著差异。     

A mechanism of resistance to methotrexate NADPH but not NADH stimulation of methotrexate binding to dihydrofolate reductase

Characteristics of methotrexate (MTX) inhibition of dihydrofolic acid reductase (DHFR) enzyme activity and the effects of NADPH and NADH on enzyme-drug interaction were studied. Two highly sensitive assay procedures were used. The first utilized tritium-labeled MTX to measure direct binding properties of the enzyme and the second utilized tritium-labeled dihydrofolate (H₂PteGlu) and folate (PteGlu) to analyze kinetics of reduction of these substrates. NADPH was found to enhance DHFR binding of MTX (K_d = 2.6 × 1O^?11 M), whereas NADH was found to have no effect (K_d = 3.7 × 10^?9 M). However, NADH proved to be a good substrate for folate reduction compared to NADPH, especially in low salt buffer. The observation that NADH supports the reduction of folate and dihydrofolate but not MTX binding suggests that natural resistance to MTX could exist if NADH replaces NADPH as the main cofactor for DHFR.