Pure rotation in the temporomandibular joint during jaw opening? A digital motion analysis.

OBJECTIVE: In the temporomandibular joint two separate movements of rotation and translation occur in two articular spaces during mouth opening. Over the years, the approach has changed considerably, but it is still subject to controversy as to which of these movement is involved in the initial stage of mouth opening. In the present study, the extent of rotation and translation was investigated in the first 5 mm of mouth opening. MATERIALS AND METHODS: The study was carried out on 46 volunteers. Anamnesis was taken and patients were examined. For the investigation, an ultrasonic digital motion analyser (KaVo Arcus Digma 2) was applied. The measurements were made after calibration to an arbitrary axis. Each participant performed three open-close movements in succession, starting from maximum intercuspal position. RESULTS: Data were statistically processed using cubic spline interpolation. Linear regression was then used. The resulting line is significantly (p < 0.0001) different from the horizontal that represents only rotational movement. CONCLUSION: The results show that during mouth opening from maximum intercuspal position, translation is present continuously in addition to rotation. Therefore, it might be time to re-evaluate the principle of a pure rotational approach.

Different methods of determining centric relation - comparison with a digital mandibular motion analyser.

BACKGROUND: Finding and registering the maxillary-mandibular jaw relation is crucial in dental practice. Several comparative studies have been conducted to investigate the reproducibility and accuracy of techniques for determining the centric relation (CR) position of the mandible. The aim of our study was to determine which of seven different CR determination methods had the smallest deviation from the theoretical zero with the help of a digital mandibular motion analyser. The chosen theoretical zero position, the maximal intercuspal position (MIP), is the most reproducible and widely used position. METHODS: Thirty-four volunteers (24 females and 10 males) with a mean (SD) age of 29.1 (± 7.3) years with a negative history of temporomandibular disorder (TMD) participated in the study. A digital mandibular motion analyser was used to register the condylar position after the use of each technique for the determination of CR. The calibration was performed to the maximal intercuspal position (MIP) for each volunteer. The investigated techniques were (A) the gothic arch tracer, (B) the adduction field method, (C) Dawson's bimanual manipulation, (D) the patient placing the tongue tip on the palatal rugae, (E) the patient placing the tongue tip to the border of the hard and soft palate, (F) the patient actively pulling the chin backwards, and (G) the examiner pushing the patient's chin back. RESULTS: The position of the mandibular condyle was illustrated in a three-dimensional coordinate system, where the origin represented the MIP. Among the seven methods examined, five showed significant deviations compared to the MIP. Among these, two methods resulted in posterior deviation of the condyles. Methods C and E coincided with the MIP in all directions. CONCLUSIONS: Within the limitations of our study, we found that the smallest deviations from our theoretical zero (MIP) among the investigated centric relation determining methods were obtained with the bimanual mandibular manipulation technique derived from Dawson and the placement of the tongue tip on the border of the hard and soft palate (linguomandibular homotrophy theory).

Dental Erosion and Its Relation to Potential Influencing Factors among 12-year-old Hungarian Schoolchildren.

PURPOSE: This cross-sectional observational study evaluated the frequency of dental erosion in 12-year-old schoolchildren in Hungary and its connection to gender, geographical region, eating/drinking habits, and to socioeconomic factors, such as the educational level of their mothers. MATERIALS AND METHODS: 579 randomly selected children aged 12 (287 boys and 292 girls) were examined in our cross-sectional study from 14 different regions in Hungary. Clinical examinations were carried out by the same examiner, using the 'Basic Erosive Wear Examination' (BEWE) index. A self-administered questionnaire was filled in by each child, surveying their oral hygiene, nutritional habits and socioeconomic status. RESULTS: 21.2% of the children showed dentitions with signs of erosion. We found statistically significantly higher BEWE scores in urban than in rural areas (p = 0.0058). There was no difference between genders. Among children drinking carbonated soft drinks once or more daily, the prevalence of BEWE score < 3 was statistically significantly lower than among those who consumed these kinds of beverages less frequently (83.6% vs 90%, respectively, p = 0.034). Children of mothers with a highschool diploma had a BEWE score ≥ 3 statistically significantly less frequently than those whose mothers had not graduated from highschool (8.4% vs 22.5%, respectively, p = 0.000). CONCLUSIONS: The prevalence of dental erosion among 12-year-old children in Hungary is not as high as reported previously in Western European countries. A positive correlation was observed between the consumption of carbonated soft drinks, the educational level of the mothers and the level of erosion. These factors statistically significantly affected the prevalence and severity of erosive dental lesions.

Multicenter study to develop and validate a risk assessment tool as part of composite scoring system for erosive tooth wear.

OBJECTIVES: (i) To develop, validate, and apply in practice a new risk assessment tool for erosive tooth wear (ETW) including a risk factors questionnaire and a saliva secretion evaluation, which combined with a clinical index, can be part of an ETW composite scoring system; (ii) to assess ETW lesions and current and past erosive challenges in younger age groups. METHODS: The Tooth Surface Loss/Erosion Working Group of the European Association of Dental Public Health consisted of an international panel of experts designed the survey component of the new tool (Erosive Wear Assessment of Risk-EWAR) and confirmed its construct and content validity. After receiving ethical approvals and informed consents, the EWAR tool (questionnaire + saliva secretion evaluation) was applied in a multicenter cross-sectional study with 207 participants aged 15-21 years old from four countries (Finland, Greece, Romania, the USA). BEWE score was used for the clinical assessment of ETW. RESULTS: A total of 58.5% of participants had ETW. 10.9% and 20.3% of participants had low secretion of stimulated (< 1 ml/min) and unstimulated saliva (< 0.25 ml/min), respectively. The following factors were bivariately significantly associated with ETW: energy drink consumption, low secretion of stimulated saliva, juices consumption, erosive drink consumption for quenching thirst between meals, erosive drink kept in the mouth, feeling pain/icing after consuming something acidic or cold, and co-existence of other type of tooth wear. In regression analysis, only energy drink consumption (OR = 3.5, 95% CI: 1.39, 8.9), low secretion of stimulated saliva (OR = 36.3, 95% CI: 4.71, 78.94), and feeling pain/icing (OR = 8.8, 95% CI: 1.92, 40.04) remained significant. CONCLUSIONS: The examiners of the study reported that the EWAR tool appeared to be an affordable and easy-to-use instrument. Some challenges occurred during the saliva collection process. Inferential analysis revealed that the risk factors/indicators of low stimulated salivary flow, energy drink consumption, and pain/icing with ETW were considered the most important in ETW occurrence. CLINICAL RELEVANCE: EWAR tool combined with the BEWE clinical index can be used for ETW risk assessment for epidemiological studies and chairside use.

[Dental erosion and gastro-esophageal reflux disease]. / Az erosio dentium és a gastro-oesophagealis reflux betegség.

The prevalence of gastro-esophageal reflux disease (GERD), as well as that of dental erosion (DE), increases steeply in the 21th century societies of Europe and North America. GERD is a multicausal disease, with genetic, anatomical and neurological insufficiencies in the background, complemented with behavioral factors. In GERD, as reflux occurs more often and lasts longer than physiologically, the result is esophagitis and supraesophageal manifestations. The acid, which might even reach the mouth, interacts with the material of the teeth and demineralization, a form of dental erosion takes place. Clinical studies have proved, that in patients suffering from GERD dental erosion takes place significantly more often than in patients who do not. It was also confirmed that in patients with idiopathic dental erosion GERD is significantly more frequent than in the "uneroded" population. These data suggest that in case of extended dental erosion the dentist should think of a - possibly not yet diagnosed - gastroenterological disease.

[Destructive and protective factors in the development of tooth-wear]. / Destruktív és protektív tényezök szerepe a fogkopások kialakulásában.

The experience of the past decade proves that tooth wear occurs in an increasing number of cases in general dental practice. Tooth wear may have physical (abrasion and attrition) and/or chemical (erosion) origin. The primary physical causes are inadequate dental hygienic activities, bad oral habits or occupational harm. As for dental erosion, it is accelerated by the highly erosive foods and drinks produced and sold in the past decades, and the number of cases is also boosted by the fact that bulimia, anorexia nervosa and gastro-oesophageal reflux disease prevalence have become more common. The most important defensive factor against tooth wear is saliva, which protects teeth from the effect of acids. Tertiary dentin formation plays an important role in the protection of the pulp. Ideally, destructive and protective factors are in balance. Both an increase in the destructive forces, and the insufficiency of defense factors result in the disturbance of the equilibrium. This results in tooth-wear, which means an irreversible loss of dental hard tissue. The rehabilitation of the lost tooth material is often very difficult, irrespectively of whether it is needed because of functional or esthetic causes. For that reason, the dentist should carry out primary and secondary dental care and prevention more often, i.e. dental recall is indispensable every 4-6 months.