Histological analysis of regeneration of temporomandibular joint discs in rabbits by using a reconstituted collagen template.

The aim of this study was to design a biodegradable implant, in the form of a reconstituted collagen template in order to promote and support regeneration of the temporomandibular joint disc. Bovine collagen (Major Type I) was pepsinized, reduced by beta-mercaptoethanol, and reconstituted by glutaraldehyde. The reconstitution of the collagen increased the resistance to biological degradation by collagenase, optimized the pore size and possessed maximum biological activity for tissue regeneration. Forty-four New Zealand rabbits underwent either sham surgical procedures or partial temporomandibular joint discectomy. In animals that underwent partial discectomy, the discs were replaced by either reconstituted collagen templates or subdermal grafts. Some of the surgerized animals did not receive any type of implant or disc substitute. Gross and histological examination of the surgerized temporomandibular joints was carried out at 1-, 2-, and 3-month intervals after surgery on the selected groups of animals. Marked arthritic changes were observed after 3 months in the partially discectomized joints without implantation. In contrast, the discs, which received a reconstituted collagen template or subdermal graft exhibited regeneration and nearly normal morpology. No foreign body response was observed in experimental groups 3 months after implantation. This study demonstrated that the reconstituted collagen did as well as subdermal grafts in supporting and facilitating regeneration of the disc and the former was found to have some advantages over the latter.

Evaluation of biomechanical properties of Expanded-Polytetrafluoroethylene Soft Tissue Patch after dorsal implantation in the rat to mimic TMJ lateral reconstruction.

Clinically, Gore-Tex Expanded-Polytetrafluoroethylene (E-PTFE) has been used to reconstruct the lateral temporomandibular joint (TMJ) ligament. The purpose of this study was to assess changes in the biomechanical properties of implanted E-PTFE over time with respect to tissue infiltration. Ninety-six specimens of implants were divided into four groups. Group A was the experimental group. Thirty-six autoclave-sterilized specimens were subcutaneously implanted into the backs of 36 rats. The rats were randomly sacrificed at 2 (n = 12), 7 (n = 12) and 12 (n = 12) weeks. The implants were tested for mechanical properties including maximal stress, strain and Young's modulus of elasticity (E) using the servo-hydraulic material testing system (MTS). Group B was the in vitro control group. Thirty-six specimens were placed in tissue culture media at 37 degrees C for a time period equivalent to the experimental group to simulate the effect of a moist, warm environment on biomechanical properties. Group C was the temperature and pressure control group. Twelve specimens were autoclave-sterilized to determine the changes of tensile strength under high temperature and pressure. Control group D (no treatment) was tested to determine the initial tensile strength. The results showed significantly larger maximal stress as well as an increase in E and smaller maximal strain in experimental group A than in control groups B, C and D. There was no significant difference among control groups B, C and D. Histological examination of implants at 12 weeks demonstrated that 0.2-0.3 mm of 1-mm thick implants were occupied by connective tissue from each side. It may be concluded that E-PTFE implants become stronger and less flexible after implantation in vivo.

Prevalence of temporomandibular disorders (TMD) in children based on physical signs.

Temporomandibular disorders (TMD) are related to the function and integrity of the masticatory system with restricted jaw movement and/or joint clicking or crepitus, for example, dominating the clinical signs of these disorders. The prevalence of TMD signs was examined in non-patient children ages six to twelve (1994 n = 185, 1995 n = 237) by four examiners using standardized techniques. Of significance was the finding that 7.3 percent of the 1994 children had audible joint sounds, while the 1995 examination reported 3 percent. Statistically significant relationships (p < 0.05) between the ages of the subjects and measurements of overbite (p < 0.0001), overjet (p < 0.01), and clicking (p < 0.005) were calculated from the 1994 data, while significant correlations for overbite (p < 0.001) and overjet (p < 0.01), but not clicking were found in the 1995 examination. One study of four- to six-year-old nonpatients reported a higher occurrence of joint sounds (48 percent). This disparity indicates a possible need for standardization of examination techniques specifically targeting joint sounds and their role in TM disorders.

Prevalence of upper extremity neuropathy in a clinical dentist population.

When asked about altered sensation in hands or arms, forearms, cervical area or neck, 29 percent of Nebraska dentists surveyed said they felt pain, followed by numbness and tingling. The prevalence suggests the possibility of an occupational concern.

Reliability and validity of instrumentation used to record nocturnal clenching and/or grinding.

Nocturnal clenching and grinding can be recorded with a portable electromyograph unit and a standard cassette tape recorder, which registers the clenching episodes on a cassette tape. The information can then be coded by a new instrument, called a Pulse Identifier, that subsequently transfers the data to a polygraph chart recorder. This study evaluated the reliability and validity of the Pulse Identifier when interfaced with other instruments that measure nocturnal clenching/grinding. A known number of clenching incidents over a baseline period of time were evaluated by three "blind" scores. The results demonstrated an interscorer reliability coefficient of 0.99 and a validity coefficient of 0.99.

A preliminary diagnostic and treatment protocol.

The objectives of the preliminary diagnostic and treatment protocol are 1. To reveal retention or resistance form deficiencies. 2. To reveal need for augmentive periodontal crown-lengthening surgical procedures. 3. To evaluate pontic form for the existing space. 4. To preplan occlusal plane deficiencies and methods of corrective treatment to establish Curve of Spee. 5. To preplan occlusal scheme, i.e., canine guidance, group function, mutually protected occlusion, and cross-bite conditions. 6. To aid in preplanning sequence of treatment and method of preservation of occlusal vertical dimension. 7. To serve as a visual aid for discussion of treatment recommendations with patient prior to actual treatment. 8. To act as a medicolegal record to document the clinician's pretreatment planning in complex treatment situations for possible use in peer review or litigation. 9. To aid in fabrication of an elastomer reduction guide for use during crown preparation. 10. To aid in fabrication of a vacuum-formed template for provisional restoration of crown and abutment teeth after preparation.

Clinical decision analysis in fixed prosthodontics.

Structured clinical decision analysis in dentistry in fixed prosthodontics, as in any branch of dentistry, allows the practitioner to think through more clearly the problems at hand based on the clinical data and extenuating factors presented by the patient. This discipline of decision making is intended to complement the experience level and educational background of the clinician in assisting him or her through the decision process. Additionally, CDA helps the clinician define not only the pre-existing condition of the patient prior to irreversible therapy, but also which treatment strategies may best be suited for that individual over an extended period. The systematic nature of decision analysis stimulates the focusing of one's attention on those factors considered to be germane to the overall complexity of the case and, at the same time, excluding those factors having little or no influence on its final outcome. With further implementation of computerized databases and procedural outcome probabilities based on clinical and laboratory studies as well as the clinical experience of those choosing to use it, the future for structured, formalized clinical decision analysis seems quite promising.

Evaluation of temporomandibular joint sounds. Diagnostic analysis and clinical implications.

This literature review and survey highlights the controversies surrounding the significance of joint sounds in general, the problems and pitfalls of joint sound analysis and interpretation, and the degree of importance given peripheral and temporomandibular joint sounds by physicians and dentists. The instrumentation and devices currently proposed for use in the detection and interpretation of joint sounds may not meet the standards of validity, reliability, sensitivity, and specificity, and as pointed out by one investigator, "The only objectivity currently associated with these instruments is their ability to record sounds of undetermined origin." In addition, no solid evidence is available that these particular sounds, when detected, are both repeatable over time and distinctly characteristic for particular disorders or significant pathologic changes. Some degree of caution should be used, therefore, when interpreting joint sounds in the absence of significant signs and symptoms of temporomandibular disorders. The clinical significance of these same sounds may become more or less apparent relative to the information obtained in a comprehensive temporomandibular disorder evaluation and examination including both subjective and objective pain assessments, mandibular range of motion measurements, and the interpretation of radiologic findings.

Clinical implications of anomalous muscle insertion relative to jaw movement and mandibular dysfunction: the anterior belly of the digastric muscle in a cadaver.

This case report of an anomalous insertion of the anterior belly of the digastric muscle in a cadaver considers the components involved in mandibular movement as well as the radiologic changes that could be expected in asymmetric function of the temporomandibular joints. The occlusal scheme of the cadaver was noted and, after transcranial radiographs were taken, both joints were anatomically dissected. While the left condyle-disc relationship appeared normal and properly approximated, the right joint (which was assumed to be translating in an anterior, inferior, and medial direction on each opening, ie, left lateral deviation) was found to have a complete articular disc perforation with severe bony erosion and condylar spicule formation. These findings may shed some light on dyskinesia diagnosis and treatment outcome; ie (1) what degree occlusally related etiologies may be affixed to individuals with aberrant mandibular movement, (2) why many diagnosed cases of mandibular dysfunction continue following irreversible dental restorative treatment via augmentation of the existing "malocclusion," and (3) what may be the clinical implications of or limitations inherent in the use of jaw-tracking devices in the diagnosis and interpretation of dyskinetic movement in the presence of aberrant muscle attachments.

Tryptophan supplementation for nocturnal bruxism: report of negative results.

This experiment was designed to study the effect of L-tryptophan on nocturnal bruxism. Portable EMG recorders were used to monitor unilateral masseter muscle activity during sleep in eight patients identified as nocturnal bruxists. Following an initial baseline period, the patients were given, in a randomized double-blind study, either tryptophan (50 mg/kg of body weight) or a placebo for 8 days followed by an additional 8 days of reverse medication. Dietary patterns and food intake were monitored throughout the experimental period. No significant treatment differences in bruxing levels were found, suggesting that L-tryptophan supplementation in the absence of dietary manipulation is ineffective in the treatment of nocturnal bruxism.

Personality hardiness, anxiety, and depression as constructs of interest in the study of temporomandibular disorders.

This study examined the stress-mediating characteristics of the personality construct of hardiness within a population of dental patients diagnosed with a temporomandibular disorder (TMD). It was found that hardiness, consisting of feelings of control and commitment, was significantly lower in TMD patients when compared with a matched control group of non-TMD subjects. A third proposed factor of hardiness, challenge, was not found to differ significantly between the groups. Anxiety and depression self-ratings also did not differ significantly between the groups.

The effect of L-tryptophan supplementation and dietary instruction on chronic myofascial pain.

Effects of L-tryptophan supplementation and dietary manipulation were tested on patients with chronic myofascial pain around the temporomandibular joints. In this study, however, reduction of chronic pain reported in previous similar studies was not duplicated. No significant reduction in pain was noted in the groups receiving tryptophan and dietary manipulation compared with control groups.

Interrater reliability in masticatory muscle palpation.

Muscle palpation is an important procedure in screening for TM disorders and assessing results of treatment outcome studies, but interpretation of response may be subjective and vulnerable to examiner bias. Masticatory muscle palpation scoring was evaluated with respect to interrater agreement on 31 myofascial pain-dysfunction patients participating in a medication study. Two clinicians independently palpated the temporomandibular joints, muscles of mastication, and related head and neck musculature on three different occasions over the 6-week period of the study. Standardization of palpation technique and initial protocol for interpretation of subject response were discussed prior to the first examination. Further clarification and reinforcement of examination methodology and scoring were carried out prior to the second examination, 1 week later. Another 5 weeks passed, with no further standardization, before the third and last examination. A behaviorally anchored scoring system (0 to 3) was used to rate response to palpation. Results indicate that two investigators can achieve a fair degree of reliability when carefully standardized, further interrater standardization can result in higher reliability, and reliability can be maintained over at least a 5-week period of time.