Lateral and protrusive contact schemes and occlusal wear: a correlational study in a young adult Saudi population

This study investigated the influence of occlusal contacts on the location and severity of occlusal wear during various mandibular movements. The study population consisted of 80 dental students with a mean age of 22 years, within the age range of 19 to 25 years. A dentition wear index--in addition to anterior, canine, and posterior subindexes--was derived from a tooth-by-tooth evaluation of casts. Lateral excursive and protrusive contact relationships were obtained by clinical examination. There was no correlation between the distribution of occlusal wear and the type of lateral excursive contact scheme. The location of contacts in protrusive movement demonstrated a distinct correlation with occlusal wear in overall severity and distribution according to segmental wear subindexes. The results indicate that the role of "disclusive protection" in the occurrence of occlusal wear may be questioned; the efficacy of "mutual protection" is similarly unsubstantiated, and the results lend further support to the concept of multifactorial etiology of occlusal tooth wear.

[The preparation of the maxillodental system before using using metal-ceramic dentures]

Orthodontic treatment using cermet dentures was carried out in 496 patients aged 26 to 60. Therapeutic surgical and orthodontic treatment of the maxillodental system was carried out before denture fixation. Late results in periods from 1 to 5 years were followed up in 396 patients. No complications were observed in 384 (96.9%). Only 12 patients developed complications: porcelain fracture in 4, periodontal inflammations in 5, and a partial relapse of occlusion reduction and distal dislocation of the mandible in 3.

Covariation of some factors associated with occlusal tooth wear in a selected high-wear sample

The aim of the present study was to investigate the significance of some factors associated with occlusal tooth wear in a selected high-wear Swedish sample. The material comprised 59 subjects having a mean age of 35 yr within the range 16-70 yr, the criteria for selection being a full or nearly full complement of natural teeth, and the presence of definite clinical signs of occlusal wear. A dentition wear index was derived from a tooth-by-tooth evaluation of casts. The results showed that men had significantly greater wear than women. Other factors which were found to correlate significantly with increased occlusal wear were: age, increased bite force, decreased occlusal tactile sensitivity, increased endurance time, and reduced tendency for crowding in the dental arches. In the salivary analysis, it was found that low buffer capacity and low rate of secretion were significantly correlated with high wear. Cephalometric variables shown to be correlated with increased wear were retroclination and position of maxillary incisors, and greater interincisal angle. The results from this study also suggest that the associations of attrition with certain dentoalveolar morphologic features are similar in the present contemporary sample and various noncontemporary populations.

An investigation of some factors associated with occlusal tooth wear in a selected high-wear sample

The aim of the present study was to investigate the influence of some factors associated with occlusal tooth wear in a selected high-wear Swedish sample. The material comprised 59 persons having a mean age of 35 yr within the range 16-70 yr, the criteria for selection being a full or near-full complement of natural teeth, and the presence of definite clinical signs of occlusal wear. A dentition wear index, in addition to anterior, posterior, and arch subindices, was derived from a tooth-by-tooth evaluation of casts. Factors which were found to correlate significantly with increased occlusal wear were age, sex, self-perception of wear, number of teeth, and general health, as well as a number of variables from study-cast analysis. On the basis of the findings, not only is the multifactorial etiology of occlusal tooth wear a reality, but so, too, is the complex interdependence of these factors in the severity of wear.

Prevalence of temporomandibular disorders in relation to some occlusal parameters

A clinical examination survey included 600 women and men between 18 and 22 years of age studied for the possible association between temporomandibular disorders and a number of occlusal parameters (Angle's classification, type of eccentric occlusion, chewing side preference, horizontal overlap value, and non-working side contact occurrence. Extraoral and intraoral examination was performed for each subject, and horizontal overlap value was determined by the use of a dial caliper gauge. The presence of non-working contacts was detected by use of the dental floss technique. The results showed high dependence between the frequency of temporomandibular disorders and class II division 1, class III patients, group function occlusion, and a high horizontal overlap value. Furthermore, class II division 2 patients showed a reduced occurrence of temporomandibular disorders in relation to the other classes. When the non-working side contacts were increased, a higher association of temporomandibular disorders was observed.

Anticipating failure in extensive restorative treatment of the periodontally compromised patient

If even one supporting tooth fails, a complex restorative treatment may have to be redone. Improved design of a restoration can anticipate failure and offer alterations to existing appliances.

Scientific evidence of occlusion and craniomandibular disorders

The rejection of the old hypothesis concerning the role of occlusal factors in craniomandibular disorders has been suggested because of the lack of evidence supporting the hypothesis. However, it would be more helpful to seek tests that clearly show that the hypothesis is wrong. Most of the studies used to favor rejection of this hypothesis have incorporated designs precluding any causal conclusions on the role of occlusal factors. Time and resources have been wasted in repeated efforts to obtain what is only associative proof; studies designed to address the causal question are few. There are, as yet, no results clearly warranting the rejection of the hypothesis that occlusal factors are part of a causal complex of craniomandibular disorders.

A multiple logistic regression analysis of the risk and relative odds of temporomandibular disorders as a function of common occlusal features

A multiple logistic regression analysis was used to compute the odds ratios for 11 common occlusal features for asymptomatic controls (n = 147) vs. five temporomandibular disorder groups: Disc Displacement with Reduction (n = 81), Disc Displacement without Reduction (n = 48), Osteoarthrosis with Disc Displacement History (n = 75), Primary Osteoarthrosis (n = 85), and Myalgia Only (n = 124). Features that did not contribute included: retruded contact position (RCP) to intercuspal position (ICP) occlusal slides < or = 2 mm, slide asymmetry, unilateral RCP contacts, deep overbite, minimal overjet, dental midline discrepancies, < or = 4 missing teeth, and maxillo-mandibular first molar relationship or cross-arch asymmetry. Groupings of a minimum of two to at most five occlusal variables contributed to the TMD patient groups. Significant increases in risk occurred selectively with anterior open bite (p < 0.01), unilateral maxillary lingual crossbite (p < 0.05 to p < 0.01), overjets > 6-7 mm (p < 0.05 to p < 0.01), > or > 5-6 missing posterior teeth (p < 0.05 to p < 0.01), and RCP-ICP slides > 2 mm (p < 0.05 to p < 0.01). While the contribution of occlusion to the disease groups was not zero, most of the variation in each disease population was not explained by occlusal parameters. Thus, occlusion cannot be considered the unique or dominant factor in defining TMD populations. Certain features such as anterior open bite in osteoarthrosis patients were considered to be a consequence of rather than etiological factors for the disorder.

Temporomandibular disorders: a survey of dentists' knowledge and beliefs

General dentists and specialists likely to treat TMD were surveyed to gain information on their understanding of TMD causes, diagnosis and treatment. While the role of psychophysiologic factors in the etiology of TMD has been widely acknowledged in the practicing community, there is still a high level of controversy about the pathophysiologic aspects of TMD and appropriate diagnoses and treatment.

[Evaluation of relation between signs of trauma from occlusion and severity of periodontitis]

The aim of the present study was to evaluate the various occlusal interferences, signs of trauma from occlusion and their relations to severity of periodontitis. 32 cases of moderate to advanced adult periodontitis patients participated in the study with a mean age of 37.6 years. All subjects received a complete periodontal examination and occlusal analysis. The results indicated that teeth with various occlusal interferences did not exhibit any greater severity of periodontitis than those without interferences. However, widened periodontal ligament space (PDLS) was frequently seen in teeth with occlusal interference. Two combined criteria were initially suggested to identify the occlusal trauma in clinic. The first criterion included presence of functional tooth mobility plus radiographically widened PDLS. The second, presence of significant tooth wear plus radiographically thickened lamina dura. The results showed that teeth with the first criteria had deeper probing depth, more clinical attachment loss and less alveolar bone support than teeth without these findings. However, teeth with the second criteria had less attachment loss and more bone support than teeth from control group. It was suggested that both of the combined criteria provide better reliability in determination of established occlusal trauma as well as evaluation of adaptive capacity of periodontal structure to increased biting force. The regression analysis demonstrated that given equal clinical attachment levels and similar inflammation, teeth with evidences of functional mobility and widened PDLS had less osseous support than teeth without these findings (P < 0.01). The difference became greater in line with the more loss of clinical attachment.

A clinical observation: a relationship of occlusal contacts to distal musculature

Dentists treating craniomandibular dysfunction frequently encounter pain and dysfunction in seemingly unrelated distal areas of the body. This is a study using manual palpation to demonstrate a change in distal muscle pain response caused by altering an apparent noxious tooth contact. Forty-four (n = 44) patients with a defined muscle involvement were selected for this study. After isolating one tooth and the single contact that influenced the muscles under observation, one or two slight alterations were made to the contact to redirect the occlusal force in all but the four control subjects. Thirty-eight (n = 38) patients showed marked relief in tenderness to palpation following minute tooth alteration in the muscles being observed. Two (n = 2) showed slight improvement. No significant change in pain to palpation was noted in the control group (n = 4). The results suggest that altering an apparent noxious occlusal contact has a direct influence on muscles in other parts of the body.

Disocclusion time-reduction therapy with immediate complete anterior guidance development to treat chronic myofascial pain-dysfunction syndrome

Successful treatment of chronic myofascial pain-dysfunction syndrome by disocclusion time-reduction therapy has been shown to be effective in 1 to 3 months, with the major muscular changes occurring in the first 30 to 40 days following initial therapy. Disocclusion time reductions have been previously reported to quickly reduce or eliminate numerous symptoms of chronic myofascial pain-dysfunction syndrome. Proper modification of an existing occlusal scheme from one that contains lengthy disocclusion time to one with short disocclusion time can be accomplished by implementing the method of occlusal adjustment known as immediate complete anterior guidance development. This paper describes the proper clinical occlusal adjustment methodology using a computerized device that shows the measurement and subsequent reduction of excessive disocclusion time. This directly lessens elevated contractile muscle activity, which leads to rapid muscular recovery of the involved dysfunctional muscle groups.

New diagnostic and therapeutic mechanical device

A new device is described that may be used (1) diagnostically to determine the relationship of the occlusion to tenderness in the lateral pterygoid and other muscles of mastication; (2) to relieve ischemic muscle tenderness; (3) to assist in the reduction of articular clicks; and (4) as a positioning device for the registration of physiologic interocclusal relations. The rationale for the causal relationship between the occlusion and lateral pterygoid muscle tenderness is explained.

The effects of infraocclusion: Part 3. Dental arch length and the midline

The third and final article in this series examines the effect of infraocclusion on the midline of the mandibular dental arch. From clinical observation, a shift in the dental midline to the side affected by infraocclusion seemed very common, and this could be explained within the terms of the hypothesis proposed in the first article. A method was devised on a panoramic radiograph to define and to distinguish the anatomic (skeletal) midline and the dental midline. This confirmed the existence of a dental shift to the affected side. The hemiarch length of each side was measured on the film, from the distal of the second deciduous molar/second premolar to both constructed midlines, and was found to be longer on the affected side, confirming an abnormally distal position of the first molar on that side.

Influence of the maxillary canine on mandibular fracture

The length of the root of the mandibular canine tooth has been considered by many authors as being a source of weakness in the mandible. It has also been suggested that a direct blow or a bending force around this tooth can result in traumatic injury. We advance a theory that implicates the maxillary canine tooth as directly contributing to the mandibular canine region fracture pattern.

The association between occlusion and attrition

The purpose of this study was to identify variables of malocclusion that might be associated with attrition and then to quantify the relationship between these variables and attrition. The results of this study indicate that, with all other factors held constant, a patient's attrition score tends to: increase with age, increase with bite depth, decrease initially with overjet until a critical value and then increase, and be unaffected by sex, interincisal angle, U1 to NA angle, Angle classification, posterior or anterior cross bites. Further, we discuss the statistical treatment of data of this kind and emphasize the importance of a professional approach to analysis.

The effects of infraocclusion: Part 1. Tilting of the adjacent teeth and local space loss

The normal arrangement of the transseptal fibers in the dentition is one of a completely horizontal system that links the mesial and the distal aspects of each tooth within the dental arch, from the most distal tooth of one side to the most distal tooth of the other, across the midline. This continuous fiber band is parallel to the occlusal plane, being attached to each tooth coronal to the level of the interradicular alveolar bone crest and apical to the cementoenamel junction. Alteration of the occlusal plane will be mirrored by a similar change in the plane of the transseptal fiber system. From the clinical observation of young people with infraoccluded deciduous teeth, over many years, the regular and concomittant occurrence of certain other, well-defined phenomena appears to be the rule. It was thought that these phenomena could be explained in terms of the inclusion of a vertical component (infraocclusion) into this horizontal system. Two of these phenomena are discussed here. The first and most obvious of these relates to the exaggerated tipping that affects the adjacent tooth mesially and distally. The second parameter measures the amount of actual horizontal (mesiodistal) space change that occurs locally, within the dental arch, between the two teeth adjacent to the infraoccluded tooth, measured at both the occlusal level and at the level of their root apices. With a high degree of statistical validity, it was found that infraocclusion is related to severe tilting of the two adjacent teeth toward the affected tooth, with minimal space loss in the dental arch at the occlusal level, but a wide separation of root apices.

A functional aspect of anterior attrition or flaring and mode of treatment

The phenomenon of occlusal wear has been generally reported, with no distinction being made between wear of the anterior or posterior teeth. This paper describes a group of patients without oral habits and exhibiting anterior tooth attrition or flaring with minimal posterior tooth attrition. The mandibular anterior movement patterns of the patients studied were evaluated using a Sirognathograph. These patterns appear to be the etiology for the anterior attrition or flaring present. A treatment mode allowing coexistence of this phenomenon with an anterior guidance that does not interfere with the mastication pattern is proposed. A hypothesis that might explain the clinical findings and a mode of treatment are described.

The relationship of occlusion, parafunctional habits and recent life events to mandibular dysfunction in a non-patient population

This study investigated the association between occlusion, oral habits and stress relative to the level of mandibular dysfunction in the total population and in specific diagnostic subgroups (normal, joint disorder, muscle disorder and joint/muscle disorder). A total of 269 nursing students were given a questionnaire and examination. The questionnaire included items to calculate an oral habit index and a social readjustment rating scale. The examination included items to calculate an occlusal index, two craniomandibular indices and a diagnostic criteria for specific subgroups. In the total population there was a positive association between mandibular dysfunction and three postulated risk factors. The total population was then divided into diagnostic subgroups. There was a positive association between the degree of mandibular dysfunction and parafunctional habits for normals, muscle disorders and joint/muscle disorders. There was a positive association between mandibular dysfunction and occlusion for normals only. Finally there was a positive association between mandibular dysfunction and stress for muscle disorders only. The results suggest that associations between postulated aetiologic factors and mandibular dysfunction vary depending on whether the subjects have a muscle and/or joint disorder. Since all associations were weak, other possible risk factors need to be investigated.