颞下颌关节病的病因问题：咬合因素的流行病学和病因学依据

咬合与颞下颌关节紊乱病(temporomandibular disorders,TMD)的关系是口腔医学领域最有争议的问题。一项大样本流行病学横断面研究(德国Pomerania地区的健康调查)发现,有15项咬合相关的指标与TMD症状、体征相关。另外一些研究也报道其他与TMD有关的咬合指标。然而,统计学研究结果并不支持这些指标与TMD之间的因果关系,用Hill 9项病因学标准评价,结果显示咬合因素与TMD之间的因果关系很弱,只有磨牙症、后牙缺失和单侧后牙反□在多项研究的结果中表现出一定的一致性,而且有证据显示,一些报道中的咬合表现可能是TMD的结果而不是病因。总之,咬合病因学的生物学证据通常很难得到,女性比男性易发TMD,□板或咬合调整虽然可以缓解症状,但不能排除颌间关系改变所产生的作用,而且TMD症状不经过治疗也可缓解。有TMD病史的患者可能更易再次出现TMD,因此关注那些已知的非咬合因素可能更有助于了解TMD的易感性、始动因素(诱因)或者持续发挥作用的因素。     

Posturography as a diagnostic aid in dentistry: a systematic review

Summary The aim of this systematic review of the literature was to assess the scientific evidence for detectable correlations between the stomatognathic system and whole‐body posture and to provide information on the relevance of posturography as a diagnostic aid in dentistry. A literature survey was performed using the Medline database, covering the period from January 1966 to May 2009, and using the medical subject headings. After selection, 21 articles qualified for the final analysis. Only one study was judged to be of medium/high quality, with all of the rest classified as of low quality design. Only two studies included follow‐up of 28 days and 1 year. Overall, 14 of the studies reported detectable correlations between the stomatognathic system and body posture in at least one of the parameters used, although in four of these studies the authors suggested caution in the interpretation of their data. After a reappraisal of the data provided in 13 of the studies, a weak correlation that reaches biological, but not clinical, relevance is apparent. With limitations because of the poor methodological quality of the present published studies, conclusions are that a correlation between the stomatognathic system and whole‐body posture can be detected, at least under experimental conditions; although posturography has little relevance in the monitoring of body posture responses to changes in the stomatognathic system (including temporomandibular disorders). While more investigations with improved levels of scientific evidence are needed, the current evidence does not support the usefulness of posturography as a diagnostic aid in dentistry.     

Dental occlusion: a critical reflection on past, present and future concepts

Summary  For nearly a century, the diversity of concepts about 'normal' and 'ideal' dental occlusal relationships has led to confusion in trying to describe the occlusion of any individual patient. In addition, a similar controversy arises when trying to formulate treatment plans for patients who need extensive dental restorations or orthodontic treatment. And finally, the application of occlusal concepts to patients with temporomandibular pain and dysfunction has created a third area of debate. Over the past few decades, however, an appreciable part of the tenacious dogmatic heritage of this topic has been challenged. As a result, the acceptance of morphological and functional variability of the stomatognathic system has gained increasing support, and this change has important consequences for modern dental practice. In this article, the past, present and future of the subject of occlusion will be considered.     

Occlusal adjustment and myoelectric activity of the jaw elevator muscles in patients with nocturnal bruxism and craniomandibular disorders

The effects of occlusal adjustments on the myoelectric activity of the anterior temporal and masseter muscles, with the mandible at rest and during maximal clenching in the intercuspal position (ICP), were studied in 24 nocturnal bruxism patients. Before the occlusal adjustment, the patients were treated with a flat occlusal splint for chronic craniomandibular disorders. The results revealed that within the short term the occlusal adjustment, in terms of increased number of occlusal contacts and teeth in contact in ICP, did not change the postural activity, whereas, on average, the level of activation of the jaw elevators, in terms of normalized electromyogram, increased during maximal clenching in ICP. The increase of activity was more pronounced in the masseter muscle than in the anterior temporal muscle.     

Computer-assisted morphological analysis of dental casts with maxillary prognathism and reversed occlusion

The morphologic characteristics of the dentition with maxillary prognathism and reversed occlusion were examined by a computer-assisted dental cast analysing system. Dental casts with normal occlusion, maxillary prognathism and reversed occlusion were selected and measured by a 3D shape measuring system. The dental arches and anteroposterior occlusal curves were approximated numerically by the polynomial expression with a fourth order and second order coefficients, respectively. The coefficients were analysed statistically. Maxillary dental arches with mandibular prognathism showed a more acuminate shape (V-shape) with a significant larger second order coefficient, while arches with reversed occlusion showed more angulate shapes (U-shape) with significantly smaller second order coefficients compared with arches with normal occlusions. However, a notable difference in the shape of the mandibular dental arches was not observed. The mandibular dental arches with maxillary prognathism were positioned backward relative to maxillary dental arches, while the arches with reversed occlusion were positioned forward. The anteroposterior occlusal curves with maxillary prognathism showed larger curvatures in maxilla and mandible, while the curves with reversed occlusion showed smaller curvatures in mandible comparing with the curves with normal occlusion. These results suggest that the present method could offer a useful and objective examination technique for the diagnosis of malocclusion.     

不同面部生长型正常及安氏Ⅱ类1分类错的前牙倾斜度及牙代偿特征

目的比较不同面部生长型正常的前牙倾斜度,以及安氏Ⅱ类1分类错的前牙代偿特征,为临床治疗提供参考。方法在X线头颅定位侧位片上对158例正常及246例安氏Ⅱ类1分类错的前牙倾斜度相关的测量指标进行分析,并研究其代偿特征。结果1）正常垂直生长型中上下颌前牙相对舌倾,水平生长型中上下颌前牙相对唇倾。2）与正常不同生长型均值比较,安氏Ⅱ类1分类错上颌前牙在不同生长型中相对于正常均唇倾,下颌前牙在垂直生长型和平均生长型中相对于正常唇倾,在水平生长型中没有变化。结论在临床矫治安氏Ⅱ类1分类错患者时,应根据患者的生长型及牙代偿特征,选择相应的矫治方法和控制重点。     

Smoking interferes with the prognosis of dental implant treatment: a systematic review and meta-analysis

AIM: This systematic literature review was performed to investigate if smoking interferes with the prognosis of implants with and without accompanying augmentation procedures compared with non-smokers. METHODS: A systematic electronic and handsearch (articles published between 1989 and 2005; English and German language; search terms "dental or oral implants and smoking"; "dental or oral implants and tobacco") was performed to identify publications providing numbers of failed implants, related to the numbers of smokers and non-smokers for meta-analysis. Publications providing statistically examined data of implant failures or biologic complications among smokers compared with non-smokers were included for systematic review. RESULTS: Of 139 publications identified, 29 were considered for meta-analysis and 35 for systematic review. Meta-analysis revealed a significantly enhanced risk for implant failure among smokers [implant-related odds ratio (OR) 2.25, confidence interval (CI(95%)) 1.96-2.59; patient-related OR 2.64; CI(95%) 1.70-4.09] compared with non-smokers, and for smokers receiving implants with accompanying augmentation procedures (OR 3.61; CI(95%) 2.26-5.77, implant related). The systematic review indicated significantly enhanced risks of biologic complications among smokers. Five studies revealed no significant impact of smoking on prognosis of implants with particle-blasted, acid-etched or anodic oxidized surfaces. CONCLUSION: Smoking is a significant risk factor for dental implant therapy and augmentation procedures accompanying implantations.     

Bruxism: its multiple causes and its effects on dental implants - an updated review

There is a growing interest in bruxism, as evidenced by the rapidly increasing number of papers about this subject during the past 5 years. The aim of the present review was to provide an update of two previous reviews from our department (one about the aetiology of bruxism and the other about the possible role of this movement disorder in the failure of dental implants) and to describe the details of the literature search strategies used, thus enabling the readers to judge the completeness of the review. Most studies that were published about the etiology during the past 5 years corroborate the previously drawn conclusions. Similarly, the update of the review about the possible causal relationship between bruxism and implant failure reveals no new points of view. Thus, there is no reason to assume otherwise than that bruxism is mainly regulated centrally, not peripherally, and that there is still insufficient evidence to support or refute a causal relationship between bruxism and implant failure. This illustrates that there is a vast need for well-designed studies to study both the aetiology of bruxism and its purported relationship with implant failure.     

北京地区黄种人数字化三维正常(牙合)模型牙冠角度和凸距的测量

目的采用层析法重建30副北京地区黄种人未经正畸治疗的数字化正常(牙合)模型,并测量牙冠倾角、转矩和凸距,为我国直丝弓托槽的研发提供基础.方法利用北京口腔医院正畸科与清华大学共同开发的牙(牙合)模型三维重建系统及测量软件进行重建和测量.结果北京地区黄种人正常(牙合)牙列的特点有:①牙冠倾角:上、下颌切牙、尖牙及上颌第二磨牙的牙冠近中倾斜度较美国人小,尤其以上、下尖牙显著.②牙冠转矩:上颌中、侧切牙的唇向倾斜度较美国人大,而上、下尖牙的舌向倾斜度较小.③牙冠凸距:下颌第一磨牙的牙冠凸距较美国人大.结论我国北京地区黄种人正常(牙合)牙冠倾角、转矩和凸距有显著的自身特点,应当积极地研制和开发基于我国正常(牙合)特点的直丝弓矫治器.     

Mandibular elevator muscles: physiology, action, and effect of dental occlusion

In spite of differences in embryologic origin, central nervous organization, and muscle fiber distribution, the physiology and action of mandibular elevator muscles are comparable to those of skeletal muscles of the limbs, back, and shoulder. They also share the same age-, sex-, and activity-related variations of muscular strength. With respect to pathogenesis, the type of muscular performance associated with the development of fatigue, discomfort, and pain in mandibular elevators seems to be influenced by the dental occlusion. Clinical research comparing the extent of occlusal contact in patients and controls as well as epidemiologic studies have shown reduced occlusal support to be a risk factor in the development of craniomandibular disorders. In healthy subjects with full natural dentition, occlusal support in the intercuspal position generally amounts to 12–14 pairs of contacting teeth, with predominance of contact on first and second molars. The extent of occlusal contact clearly affects electric muscle activity, bite force, jaw movements, and masticatory efficiency. Neurophysiologic evidence of receptor activity and reflex interaction with the basic motor programs of craniomandibular muscles tends to indicate that the peripheral occlusal control of the elevator muscles is provided by feedback from periodontal pressoreceptors. With stable intercuspal support, especially from posterior teeth, elevator muscles are activated strongly during biting and chewing with a high degree of force and masticatory efficiency, and with relatively short contractions, allowing for pauses. These variables of muscle contraction seem, in general, to strengthen the muscles and prevent discomfort. Therefore, occlusal stability keeps the muscles fit, and enables the masticatory system to meet its functional demands.     

Evidence-based considerations for removable prosthodontic and dental implant occlusion: a literature review

The dental literature is filled with discussions of dental occlusion, occlusal schemes, philosophies, and methods to correct and restore the diseased, worn, or damaged occlusion. Traditionally, these discussions have been empirical in nature and not based on scientific evidence. Due to the empirical nature of the literature, the study of occlusion has been extremely complex and troublesome to both pre- and post-doctoral students. The introduction of osseointegrated implants has further complicated the situation. Dentists may apply the principles of occlusion for the natural dentition directly to implant-supported and retained restorations. Although this may be successful, this rationale may result in overly complex or simplified treatment protocols and outcomes. There is an emerging body of scientific literature related to dental implant therapy that may be useful in formulating treatment protocols and prosthesis designs for implant-supported restorations. This review focuses on some of the "classic" removable prosthodontic literature and the currently available scientific literature involving removable prosthodontic occlusion and dental implant occlusion. The authors reviewed the English peer-reviewed literature prior to 1996 in as comprehensive manner as possible, and material after 1996 was reviewed electronically using MEDLINE. Electronic searches of the literature were performed in MEDLINE using key words-animal studies, case series, clinical trials, cohort studies, complete denture occlusion, dental implant function, dental implant occlusion, dental implant occlusion research, dental implant functional loading, dental implants, dental occlusion, dental occlusion research, denture function, denture occlusion, dentures, implant function, implant functional loading, implant occlusion, occlusion, and removable partial denture occlusion-in various combinations to obtain potential references for review. A total of 5447 English language titles were obtained, many of which were duplicates due to multiple searches. Manual hand searching of the MEDLINE reference list was performed to identify any articles missed in the original search.     

Non-carious cervical lesions and occlusion: a systematic review of clinical studies

Non-carious cervical lesions (NCCLs) are a group of lesions that affect the cervical area of the teeth. Different aetiological factors have been reported, among them tooth brushing force, erosive agents and occlusal forces. The aim of this study was to ascertain, by means of a systematic review, the association between NCCLs and occlusion. A search was performed in the MEDLINE database, retrieving a total of 286 articles. After title and abstract screening, the clinical investigations were read in full to select those that evaluated the occlusal aspects of NCCL aetiology. This systematic review describes the results of three prospective and 25 cross-sectional studies. As there is an extreme heterogeneity in design, diagnostic criteria, forms of analysis and associated factors, a meta-analysis was not possible. The wide variety of classification and diagnostic criteria reflects a high range of reported prevalence. An extensive heterogeneity of independent variables was noted, even in occlusal analysis, which helps to mask any conclusion about the role of occlusion in NCCL aetiology. The literature reveals that studies on this topic are subject to a substantial amount of bias, such as evaluation (use of non-blinded examiners) and confounding bias (no control of others aetiological factors). Up to now, it has been impossible to associate NCCLs with any specific causal agent, and the role of occlusion in the pathogenesis of non-carious cervical lesions seems as yet undetermined. Therefore, additional studies, properly designed to diminish bias, are warranted.     

Novel anticoagulants: general overview and practical considerations for dental practitioners

Currently, 4 novel Direct Oral Anticoagulants (DOACs) were approved by the FDA. This review focuses on these agents and proposes a matrix for the general dentists to assess bleeding risk in dental management of patient on DOACs. The outline covers the pharmacology of DOACs (rivaroxaban, apixaban, edoxaban and dabigatran), bleeding complications, risk associated with discontinuation, monitoring/reversal, and implications for the dental practitioners. A total of 18 randomized controlled trials were identified with mixed results in regards to the risk for bleeding. Considering the pharmacology of DOACs and challenges in monitoring and reversing their effect, the dentist should consider carefully the management of patients on DOACs as it may differ from patients on conventional anticoagulants. Based on the type of dental procedure and the medical risk assessment, several general treatment approaches can be considered: continue DOACs, time dental treatment as late as possible after the last DOACs dose, discontinue DOACs for 24hrs, or discontinue DOACs for 48hrs. Based on the current reported dental literature, limited dental surgery may benefit from the first 2 conservative options. However, this needs to be proven in comparative clinical trials.     

The shortened dental arch revisited: from evidence to recommendations by the use of the GRADE approach

Clinicians must frequently decide whether or not to treat patients with loss of posterior teeth, a condition called the shortened dental arch (SDA). Although many studies have been reported, there are no clear recommendations for the management of SDA cases. In this work, therefore, an innovative system, the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, was used to grade the evidence and strength of recommendations for clinical intervention. An extensive literature search for longitudinal studies was conducted on 17 November 2010 in the PubMed and LILACS electronic databases using the term shortened dental arch. A 'snowballing' strategy, for example, manual searching of the reference lists of included papers, was also conducted. Unpublished and published studies were sought in ClinicalTrials.gov and in the search engine 'Google' (Scholar) in English, French, German, Italian, Portuguese and Spanish. Finally, grey literature was searched in OpenSIGLE (System for Information on Grey Literature in Europe). Titles and abstracts of 133 articles were initially assessed. Nine studies were finally included. Although there was no difference between the effectiveness of restorative and non-restorative approaches for SDA, fixed partial dentures seem better than removable prostheses. The overall body of evidence was, however, graded as low quality. Two different clinical scenarios are used to illustrate recommendations in the management of SDA cases by the use of the GRADE system. The GRADE approach may improve transparency in a shared decision-making process, mainly under conditions in which the quality of evidence is low or unclear.     

Pattern of clefts and dental anomalies in six-year-old children: a retrospective observational study in western Norway

Objectives: Clefts of the lip and/or palate (CL/P) are the most common congenital disorders of the head and neck. In Norway, the incidence is 1.9/1000 live births. The aim of this study was to investigate the frequency and distribution of various types of clefts and dental anomalies in patients treated by the cleft lip and palate (CLP) team in Bergen, Norway.

Material and methods: The material comprised the records of patients 6 years of age, examined by the CLP team in Bergen from spring 1993 to autumn 2012, incomplete records were excluded. The records of 989 patients were analysed, using frequencies and Chi-square test to compare differences in percentages between groups.

Results: The gender distribution was 58.8% male and 41.2% female. Isolated cleft palate (CP) was the most common condition (39.5%). Clefts of the lip, jaw and palate (CLP) constituted (30%) of cases and (30.5%) had isolated cleft lip (CL). The frequencies of agenesis, supernumerary and peg-shaped teeth were (36.5%), (17.8%) and (7.5%), respectively. Over 50% of the study population were diagnosed with one or more malocclusion. Of the CLP patients, 61.4% had Angle Class III occlusion. Statistical analysis disclosed a positive association of agenesis with Class III occlusion (OR =1.8, p≤?0.001).

Conclusions: The findings supported the hypothesis that the distribution of dental anomalies and occlusal disorders varied among patients with CL, CP and CLP. In patients with cleft, there is a twofold chance to get Class III malocclusion in the presence of agenesis.