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The etiology, diagnosis and treatment of temporomandibular joint (TMJ) pain and dysfunction is a controversial subject. There are varying opinions regarding the contribution of occlusion (malocclusion) to the development of mandibular dysfunction and further, the contribution of occlusal alterations (orthodontic and restorative) to the development of pain and dysfunction. Epidemiologic investigations suggest there is a high incidence of subjective and objective symptoms in the pediatric population. Observations on incisal relationships, condyle position and joint sounds, and comparisons to controls seem to suggest that these factors are not the cause of pain or dysfunction.

The purpose of this review is: (1) to bring to the clinician's attention existing published information reporting the presence of symptoms in children, (2) to evaluate selected information in young adults, (3) to question anecdotal information on the etiology of TMJ problems. It is not in the purview of this paper to determine the overall etiology of TMJ dysfunction.

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Pressure from the tongue on the teeth was measured at the upper and lower central incisors and left first molars in 25 young adults with clinically normal occlusion. Repeated recordings with and without a period for accommodation to the intraoral measuring device, which was connected to an extraoral pressure transducer, were made in the rest position and during chewing and swallowing.

Only minimal effects of accommodation were found. The system can thus be used without a period of adaptation before the actual test. The intraindividual pressure variations were of the same magnitude as for measurements of the pressure from the oro-facial soft tissues on the teeth recorded in earlier studies.

The majority of the subjects had negative pressures at the upper and lower incisors and at the upper molar in the rest position. The pressures on the teeth during swallowing were comparatively great, while pressures during chewing were one-fourth to one-half of the swallowing pressures.

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The effect of two proprietary alkaline gluteraldehyde solutions on the strength (failure load) and the required displacement or stretching to achieve a force of 500g was studied for six types of elastomeric chains. The effect of disinfection (short-term exposure) and sterilization (long-term exposure) as well as repeated immersion cycles on these parameters was evaluated.

The findings showed that exposure to gluteraldehyde solution affected the strength and the distention required to deliver a force of 500g of certain elastomeric chains. However, the resultant changes were relatively small and are probably insignificant in the clinical setting.

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White spot decalcifications and caries occurring adjacent to bonded orthodontic brackets have long been a concern to orthodontists. One procedure suggested to overcome this problem is fluoride treatment prior to bonding. The purpose of this study was to compare the tensile bond strength of orthodontic self-cured resin from Concise on teeth rinsed 4 minutes in 1.23% APF with untreated controls. Measurements were made on an Instron machine. Debonding interfaces were observed with a scanning electron microscope and energy dispersive x-ray spectrometry. Distributions were calculated. The tensile bond strengths of the fluoride-treated teeth and the untreated teeth were not significantly different. The debonding interfaces between resin and bracket base, within the resin itself, and between enamel and resin were similar in the two experimental groups. However, greater enamel detachment was seen within the fluoride pretreatment group. So while fluoride pretreatment does not significantly affect tensile bond strength, it may cause enamel detachment after debonding.

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The purpose of this investigation was to determine the shear and tensile bond strengths of various ceramic and ceramic-filled brackets in combination with commonly used bonding systems, One monocrystalline, two polycrystalline and one ceramic-filled plastic bracket types were tested in combination with one light-cured and two chemically-cured bonding systems. Bonding procedures were performed on properly prepared human teeth. Shear and tensile tests were performed on an Instron test machine. The shear bond strength of the mono-and polycrystalline ceramic brackets was not affected by the bonding system. There was a difference among bonding systems used with the ceramic-filled plastic bracket. Ceramic-filled plastic and polycrystalline ceramic brackets exhibited the greatest resistance to tensile force, while monocrystalline brackets showed the highest propensity for tensile fracture of the wings.

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An x-ray cephalographic method was used to analyze 52 exceptionally well-balanced white adult faces for skeletal asymmetry in the posteroanterior (PA) projection. Three frontal facial lines were constructed using bilateral skeletal landmarks: latero-superior orbit (LO), lateral zygoma (Zyg), and gonion (Go). All subjects demonstrated measurable asymmetries. Data showed less asymmetry and more dimensional stability as the cranium is approached. A slight tendency toward right-side dominance was not statistically significant.

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The occurrence of different occlusal and space anomalies was studied in groups of 642 Tanzanian and 458 Finnish school-children. Similar diagnostic criteria and methods were used in both countries. The Finnish children had significantly higher prevalences of distal occlusion and crowding and a lower prevalence of anterior openbite than the Tanzanian children. The proportion of subjects with no occlusal or space anomalies was considerably higher among the Tanzanians than among the Finns, 55% and 12% to 22%, respectively. The distinct differences found in occlusion of Tanzanian and Finnish children in this study seem to reflect differences in hereditary or environmental factors, which are expressed as craniofacial or dentoalveolar differences between these ethnic groups.

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The relationship between static occlusion and functional occlusion was evaluated in 101 dental and dental hygiene students. The sample was selected from a population of 467 students who were enrolled at one dental school during the 1987–1988 academic year based upon the following criteria: age range 18 to 32 years; caucasian race; no prior orthodontic treatment; at least 28 natural teeth present; no occlusal adjustments; and no large restorations, crowns or bridges. Fifty-two (52) of the subjects possessed “normal” static occlusion, 26 had a Class I malocclusion, 16 were found to have a Class II malocclusion, and 7 had a Class III malocclusion. The majority (i.e., 75%) of the 101 subjects possessed non-working (balancing) functional contacts. Seventy-five (75) of the subjects possessed balanced occlusion, nine had canine-protected occlusion, nine possessed group function occlusion, and eight had mixed canine-protected/group functional occlusion. This study found no statistically significant relationship between static occlusion and functional occlusion, however, there was a trend for balanced occlusion to be more often associated with “normal” (ideal) static occlusion.

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Correction to Volume 60, Issue 4, page 305.