Let them eat cake: the struggle between form and substance in orthodontic clinical investigation

Events of the past decade or so argue that there is little support in the literature for much of the specialty's treatment portfolio. The resulting call for ‘evidence-based’ treatment (not to mention the obvious intellectual bankruptcy of much of the clinical literature) has prompted many to argue that the randomized clinical trial (RCT) represents the future of orthodontic clinical investigation. The RCT, after all, is medicine's gold standard; what more is there to say? A popular, but ultimately divisive, corollary of this mimicry is the smug tendency to discount all other sources of data. In the face of a need for information, this attitude is also a wasteful conceit: in the end, the RCT can be applied only to a very narrow spectrum of orthodontic questions. Randomization implies equal susceptibility. Any prospective participant would have to be informed of this equality as part of the informed consent process. Unfortunately, it would be nearly impossible to enroll fully-informed subjects into any study whose alternatives are of markedly different morbidity: extraction versus non-extraction or orthodontics versus surgery. Thus, when measured against the most vexing clinical questions, the orthodontic RCT is almost by definition an amusing diversion - expensive, but relatively trivial in scope. Like it or not, it seems reasonable to conclude that most of the specialty's comparative clinical data will have to be generated by way of non-randomized designs in which care is taken to minimize the various known sources of bias. There probably is no other way.     

Unlocking orthodontic malocclusions: an interplay between form and function

It is possible to unlock dental malocclusions in a functional or mechanical manner, or in a combination of these two processes. Functional unlocking starts with an in-depth diagnosis of all aspects of a specific malocclusion including a recognition of those craniofacial dysfunctions that may be present. Craniofacial dysfunctions that may require treatment include those that involve the vegetative processes of breathing and swallowing and all aspects of cranial posture. This form of unlocking deals with the working environment of the oral cavity, that here, is also referred to as the oral functional matrix. Functional unlocking encompasses cognitive awareness training that involves patients in the treatment of their dysfunction. The early resolution of oral dysfunctions is not only an essential part of orthodontic treatment but it is also a vital component of the stability of the treatment results obtained. Mechanical unlocking, in contrast to functional unlocking, removes occlusal interferences that could interfere with the development and function of the entire stomatognathic system. Both functional and mechanical unlocking are often overlooked in orthodontic diagnosis and treatment planning. This article uses clinical examples, where possible, to illustrate how malocclusions may be unlocked to provide better and more stable treatment results.     

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目的研究成人错畸形患者的心理状态,探讨解决方案。方法选择2007年1月至2008年12月在大庆油田总医院集团五官医院口腔科和大庆油田总医院口腔正畸科就诊的成年错畸形患者30例,应用汉密顿焦虑(HAMA)、汉密顿抑郁(HRSD)量表对成人口腔正畸患者矫治前后进行心理状况评定。结果矫治前患者HAMA、HRSD的测量结果明显高于正畸矫治加心理支持治疗后的结果,其差异有统计学意义(P<0.05)。结论成人正畸患者在治疗前普遍存在焦虑、抑郁等临床心理问题,正畸矫治加有针对性的心理支持可改善患者的心理问题。     

A clinical investigation of the efficacy of low level laser therapy in reducing orthodontic postadjustment pain

Low level laser therapy (LLLT) has been shown to produce analgesic effects in many clinical applications. The aim of this clinical study was to test the efficacy of LLLT in controlling orthodontic postadjustment pain. Thirty-nine volunteers were selected for this study that used a double-blind design with placebo control. Elastomeric separators were placed at the proximal contacts of one premolar in each quadrant of the dentition to induce orthodontic pain. The tip of a 30 mW gallium-arsenide-aluminium (830 nm) diode laser probe was then placed at the buccal gingiva and directed at the middle third of the root. Three different treatment durations of 15, 30, and 60 seconds and one placebo treatment of 30 seconds were tested within each subject. The study was conducted over 5 days, and the visual analogue scale (VAS) was used to quantify the pain experienced by the subjects before and after laser applications for each day. Analysis of the VAS median scores showed that teeth exposed to laser treatment had lower levels of pain as compared with those with the placebo treatment. However, nonparametric statistical analysis of the data showed that the differences between treatments and placebo within each subject were not statistically significant. (AM J ORTHOD DENTOFAC ORTHOP 1995;108:614-22.)     

Relationship between substance P and interleukin-1beta in gingival crevicular fluid during orthodontic tooth movement in adults

Metabolism by peptidases plays an important role in modulating the levels of biologically-active neuropeptides, while that of substance P (SP), a component of gingival crevicular fluid (GCF), may potentiate the inflammatory process in orthodontic tooth movement. The aim of this study was two-fold: (1) to investigate GCF levels of SP and interleukin-1beta (IL-1beta) during human orthodontic tooth movement, and (2) to determine the correlation coefficients between SP and IL-1beta levels in the GCF. The subjects were 3 males, with a mean age of 21.3 +/- 2.8 years old, and 6 females, with a mean age of 23.1 +/- 2.4 years, undergoing orthodontic movement of a single tooth, with the contralateral tooth used as the control. GCF was sampled at the control and treatment (compression) sites before and 1, 4, 8, 24, 72, 120, and 168 hours after initiation of orthodontic treatment. Prevention of plaque-induced inflammation allowed assessment of the dynamics of mechanically stimulated SP and IL-1beta levels in the GCF, which were determined using enzyme-linked immunosorbent assay (ELISA) kits. GCF levels of SP and IL-1beta for the treated teeth were significantly higher (P < 0.001) than for the corresponding control teeth from 8 to 72 hours, and peaked at 24 hours. These results show that the amounts of SP and IL-1beta in GCF increase with orthodontic tooth movement, and indicate that such increases may be involved in inflammation in response to mechanical stress.     

正畸支抗种植体骨整合与稳定性的实验研究

目的　考察正畸支抗种植体的骨整合与稳定性以及二者之间的关系。方法　将HA涂层钛种植体、钛浆喷涂钛种植体、未涂层钛种植体植入狗股骨 ,愈合期后施加 1 96N正畸力 2个月。测量施力后种植体的位置变化和种植体—骨界面的剪切结合强度 ,用扫描电镜观察界面。结果　 3种种植体位移分别为 (- 0 5 0± 1 78)mm、(- 0 0 5± 1 76 )mm、(0 2 9± 1 77)mm ,统计学分析结果显示 ,还不能认为 3种种植体出现移动。 3种种植体—骨界面的剪切结合强度分别是 (2 88± 0 5 5 )MPa、(1 89± 0 81)MPa和 (2 14± 0 49)MPa。HA涂层种植体与骨紧密结合 ,其界面结合强度最高 ;另外 2种种植体与骨的结合强度差异无显著性。结论　虽然HA涂层种植体与骨结合最牢固 ,但 3种种植体—骨界面均可形成骨整合 ,在常规正畸力作用下不会发生明显移动。本项研究结果表明 ,种植体可用作短期的正畸支抗。     

Intraoral aging of orthodontic materials: the picture we miss and its clinical relevance.

The purpose of this editorial is to systematically analyze the variety and potency of various aging variables affecting the morphology, structure, and mechanical properties of polymeric and metallic orthodontic materials. The effects of aging on the longevity of the bond strength and mechanotherapy were analyzed: aging-induced plasticization of resin adhesives might lead to bond failure at forces of magnitude lower than those sustained at the initiation of treatment. Standard in vitro methodologies cannot show this effect, and thus laboratory bond strength protocols require modification to become clinically meaningful. Also, the force transferred from an activated archwire to a preadjusted bracket slot, as well as friction during free sliding, seems to be affected by the intraorally induced alteration of materials. Although the effect of intraoral environmental conditions on the superelastic properties of nickel-titanium (Ni-Ti) archwires and coil springs requires further research to establish the true spectrum of effects, it has been suggested that intraoral temperature variations might transiently affect their properties and that the fracture resistance of used Ni-Ti wires is reduced. Clinical implications are discussed for (1) in vivo-aged elastomeric ligatures and chains, which can be postulated to express much higher creep than their in vitro-aged counterparts; (2) the largely unknown effect of aging on the spring component of self-ligated brackets and the associated effect on ligation force; and (3) the intraorally induced alterations in the structural conformation of Invisalign appliances (Align Technology, Santa Clara, Calif). The objective of future research efforts in the field of orthodontic materials should include the development of clinically relevant methodologies. A clear definition of limitations of laboratory experimental configurations might be instrumental in confining the clinical impact of research findings to their actual extent.     

On the relationship between crown form and clinical features of the gingiva in adolescents

Abstract The purpose of the present study was to examine the relationship between the form of the crowns in the maxillary front tooth segment and (1) a group of morphological characteristics and (2) the thickness of the gingiva. 108 subjects devoid of symptoms of destructive periodontal disease were examined regarding, e.g., probing depth, thickness of the free gingiva, width of the keratinized gingiva and the contour of the marginal gingiva. From clinical photographs of the maxillary front tooth region, the width (at the apical third – CW) and the length (CL) of the crowns of the 6 front teeth were determined. A CW/ CL-ratio was calculated for each tooth and averaged for each tooth region. The individual mean CW/CL-ratio values for the central incisors were ranked. After correction for incisal attrition, the 10 subjects ranked highest and the 10 ranked lowest were selected as having either a long-narrow (group N) or a short-wide (group W) form of the crown of the tooth. The data for each of the examined parameters were averaged for each tooth region in each subject and mean values for subjects in groups W and N were compared using the Student t-test. Stepwise multiple regression analysis, including data from the whole sample, was performed for each tooth region with the thickness of the free gingiva as the dependent variable. The results from the analyses demonstrated that individuals with a long-narrow form of the central incisors displayed, compared to individuals with a short-wide crown, form (i) a narrow zone of keratinized gingiva, (ii) shallow probing depth, and (hi) a pronounced “scalloped” contour of the gingival margin. There was no significant difference between groups N and W with respect to the thickness of the free gingiva. The CW/CL-ratio data revealed that a certain form of the crowns in the central incisors was accompanied by a similar form in the lateral incisor and canine tooth region. The regression analyses demonstrated that the thickness of the free gingiva in central incisors was significantly related to (i) the width of the keratinized gingiva, (ii) the buccolingual width of the crown and (iii) the presence of an interproximal gingival groove. In lateral incisors, the thickness of the free gingiva was associated with the probing depth at the buccal surface. No single variable was significantly related to the thickness of the gingiva in canines.     

Simplified orthodontic tooth movement with dental implants and orthodontic elastics: a clinical report

Lack of adequate mesiodistal space and/or incorrect implant placement may not provide adequate space for the fabrication, insertion, and maintenance of implant crowns. This report describes the clinical presentation of a patient requiring restoration of a dental implant without adequate interproximal space due to mesial drift of the adjacent tooth. Orthodontic tooth movement was achieved with an osseointegrated dental implant and orthodontic elastics.     

Lower incisor extraction in orthodontic treatment. Four clinical reports

Four different clinical cases in which the treatment plan finally selected included the extraction of one lower incisor and reduction of upper anterior tooth width.     

潍坊市区适龄儿童正畸治疗需要调查

目的:了解潍坊市区适龄儿童正畸治疗需要情况,以指导正畸临床治疗和卫生宣教工作。方法:运用正畸治疗指数(IOTN)的2个评价指标DHC-IOTN和AC-IOTN,调查市区1022名恒牙初期儿童的牙情况。运用2χ检验进行统计学分析。结果:DHC-IOTN结果:明确需要正畸治疗者(4～5级)232人(22.7%),中度需要和不需要治疗者分别为263(25.7%)和527(51.6%);AC-IOTN结果:明确需要正畸治疗者(8～10级)65人(6.3%),中度需要和不需要治疗者分别为195(19.1%)和762(74.6%);DHC与AC结果间差异有显著性;性别间差异无显著性。错畸形患病率最高为牙列拥挤(28.1%),其余依次为深覆盖、深覆、反、开、阻生牙等。结论:潍坊地区适龄儿童客观正畸治疗需要和其自身主观感知存在差异,需加大口腔正畸学知识的宣传。     

Surgically assisted rapid palatal expansion: orthodontic preparation for clinical success.

Close root proximity between the maxillary central incisors presents a problem in the surgical management of a maxillary palatal expansion. During the surgical fracture of this interdental area, the possibility exists for a separation to occur between the root surface and the bone. If this does occur, it is paramount that the gingival attachment remain intact. Asymmetric separation places more stress on the mesial gingival attachment because of the anatomy of the gingival fiber apparatus. Gingival detachment results in epithelial downgrowth in an apical direction, which in turn prevents bone apposition in a coronal direction. The resulting osseous defect is difficult to treat with an osseous graft procedure, as there are few if any intrabony walls. Treatment planning should include analysis of a recent periapical radiograph of the incisor roots to determine the need for orthodontic root separation before surgery. A postsurgical periapical radiograph should be taken to determine where the interdental separation has occurred. The expansion schedule should be adjusted depending on the symmetry of the separation and the health of the gingival attachment.