Esther Gazit

The intercuspal surface contact area registration: an additional tool for evaluation of normal occlusion.

Abstract No Abstract Available. From the Department of Orthodontics, Tel Aviv University, Tel Aviv, Israel.

Effect of Controlled Masticatory Exercise on Pain and Muscle Performance in Myofascial Pain Patients: A Pilot Study

Abstract The aim of this study was to test the hypothesis that strengthening masticatory muscles using a controlled chewing exercise protocol improves muscle function, as evaluated quantitatively by electromyogram, and reduces pain at rest and during function. The study included 20 patients diagnosed with myofascial pain according to the Research Diagnostic Criteria for Temporomandibular Disorders with low masseter volume increase during maximal clench. The exercise group (ten patients) was subjected to a controlled gum chewing exercise protocol for eight weeks: the control group (ten patients) received only support and encouragement. Patients were examined at the beginning and at the end of the experiment which included an electromyogram (EMG) to assess muscle performance, masticatory muscle tenderness to palpation, mouth opening range, subjective anamnestic indices to evaluate pain perception and pain relief, and chewing tests. The EMG showed that the masticatory muscle exercise did produce objective physiologic results. In the exercise group, a significant increase was found in the electric muscle activity of the masseters during maximal voluntary clench (p=0.007). The exercise group showed significant reduction in pain during rest, pain during the chewing test, and a disability score. At the end of the study, a difference between the two groups was shown in the Pain Relief Scale: significantly greater pain relief was found in the exercise group as compared to the control group (p=0.019). For all other clinical parameters, there was no difference between the two groups or interaction between time and treatment. The results of this study seem to be equivocal. Additional experiments on larger population groups with extended chewing protocols are necessary before a more substantial conclusion can be reached.

The effect of pain from orthodontic arch wire adjustment on masseter muscle electromyographic activity

Pain has been shown to have an effect on muscle activity even when it does not originate in the muscle itself or in the related joint. The effect of pain from arch wire adjustment on jaw muscle activity is unclear. This study systematically evaluated the effects of orthodontic arch wire adjustment pain on masseter electromyographic (EMG) activity and on the swallowing threshold. The EMG recordings were made on 22 subjects (ages 11 to 15) under three conditions: chewing five peanuts (10 seconds), watching TV chewing gum (15 minutes), and watching TV with no gum (15 minutes). An arch wire adjustment or placebo adjustment was then made. Subjects returned after 48 hours, and the EMG measurements were made under the same conditions. After 3 weeks, subjects received arch wire or placebo treatment in a crossover design with identical recording procedures. The EMG levels while chewing peanuts decreased in 18 of 22 subjects after treatment, compared with 9 of 22 subjects after the placebo. While watching TV with gum, the EMG levels of 20 of 22 subjects decreased after treatment, compared with 9 of 22 subjects after the placebo. The number of chewing strokes before swallowing increased significantly after treatment compared with after placebo. The results suggest that orthodontic pain on teeth tend to reduce muscle activity during function.

Centric slide, bite force and muscle tenderness changes over 6 months following fixed orthodontic treatment.

OBJECTIVE The postorthodontic change of the masticatory muscles was evaluated using three parameters: maximal voluntary bite force (MVBF), slide in centric (difference between maximal intercuspation and retruded contact position), and muscle sensitivity to palpation. MATERIALS AND METHODS MVBF was measured with a custom-made rubber tube bite force device, centric slide with a digital caliper, and sensitivity to palpation of the masseter and temporalis muscles (scale 0-3) during application of standardized digital force (10 N). Data were collected at four time points: T0, before bracket removal; T1, immediately after bracket removal; T2, after 3 months of retention; and T3, after 6 months of retention. Patients (n = 41; 22 females, 19 males; mean age 17.4 +/- 5.4 years) were examined from T0 to T1 and from T1 to T2. Of these, 28 (15 females, 13 males) were followed at T3. RESULTS Immediately after bracket removal (T0 to T1), MVBF increased significantly by 15%. Another significant increase (15.5%) was found 3 months posttreatment (T1-T2), and almost no increase (2%) at 6 months (T2-T3). The slide in centric remained within normal values during the three time points. A decline in sensitivity to palpation from T1 to T3 was found for both masseter and temporalis muscles. CONCLUSIONS Neuromuscular adaptability begins within several minutes after bracket removal. A second stage of muscular adaptation occurs within 3 months of retention. These findings suggest that muscular adjustment occurs within a short period after orthodontic treatment.

Functional Disturbances of the Masticatory System in an Elderly Population Group

The purpose of this study was to determine the prevalence of craniomandibular disorders in a geriatric population in Israel, and to study morphometric and functional parameters as well. One hundred ten elderly subjects (61-90 years old) were interviewed and examined clinically for the following parameters: general health history, dental comfort and masticatory performance, anthropometric measurements, functional performance of the stomatognathic system, dental status, static and dynamic occlusion, and signs and symptoms of craniomandibular disorders. The results indicate that (1) loss of hearing was the most common debilitating functional disturbance reported, with rheumatoid or rheumatoid-like chronic diseases also common among this age group; (2) chewing performance was compromised and tongue thrust was common; (3) range of mandibular movement was decreased; (4) prevalence of signs and symptoms of craniomandibular disorders in the elderly were compatible with or higher than those in younger subjects, but the older individuals were not disturbed by the problem enough to seek help; (5) there was no association between impaired general health and the prevalence of craniomandibular disorders; and (6) interocclusal distance was large and negatively related to the lower third of the face and positively related to the presence of full dentures.

Correction of a Class I Skeletal Open-Bite Malocclusion

Abstract No Abstract Available. From the Departments of Orthodontics and Occlusion, School of Dental Medicine, Tel Aviv University, Ramat Aviv, Israel.

A comparative study of three therapeutic modalities in a temporomandibular disorder (TMD) population.

A comparative study of three treatment modalities, pharmacologic, occlusal appliance, and their combined use, was conducted to test their therapeutic efficacy on 61 temporomandibular disorder (TMD) patients. Alprazolam (Xanax) was used for the pharmacologic treatment; the occlusal appliance therapy consisted of a flat maxillary stabilization splint. Of the 61 patients, 19 received Alprazolam, 30 received occlusal appliance therapy, and 12 received combined therapy. Subjects were examined at two-week intervals for two months. Only 42 patients attended all follow-up visits. Eight parameters were studied: severity of pain, periodicity of pain, self-evaluated stress, muscle sensitivity to palpation, joint sensitivity to palpation, joint noises, limitation of opening, and limitation of lateral movement. No significant difference was found between the treatment modalities for most of the parameters. All three proved to be effective. Alprazolam increased the restricted mandibular movement, was least effective on joint sensitivity to palpation, and had no effect on joint noises. The combined treatment approach not only failed to prove superior to the other treatments, but showed less improvement in some parameters, possibly due to the small sample.

Splints and stress transmission to teeth: an in vitro experiment

OBJECTIVE To determine the influence of hard and soft splints with two thicknesses on the stress transmission to the tooth supporting the splint and the opposite tooth. METHODS Continuous vertical forces up to 500N were applied to two opposite first molar phantom teeth using a universal loading machine. Deformation was detected by strain gauges attached to the cervical area of the buccal and lingual aspects of the lower tooth. Strain, as a function of force, was collected and the slope, defined as the compliance (in microS/N) of the system, was calculated. RESULTS The highest compliance was found with hard splints. When splints were constructed on the upper molar, the highest compressive compliance was registered on the buccal side (2.8 microS/N) and tension compliance on the lingual side (-0.35 microS/N). When constructed on the lower tooth, the opposite was found. Soft splints resulted in compression on both the buccal and lingual sides when adjusted to the upper or lower tooth. A higher compliance was found on the buccal side (1.26 microS/N), while on the lingual side, the values varied (0.48-0.78 microS/N). CONCLUSIONS Soft splints are more efficient in protecting teeth against the damage of bending forces although there is an increase of compression forces. The tooth opposing a hard splint is exposed to a higher risk of bending forces.

Upper first premolar with congenitally missing buccal root: A case report

The endodontic literature is replete with descriptions of teeth having alterations, aberrations, or additions of roots or root canal formations (1, 2). The occurrence of congenitally missing roots, however, is most unusual. Andreasen (3) reported that partial or complete arrest of root formation is a rare complication of ment plan called for extraction of the upper first premolar teeth. Panorex and periapical X-ray films showed no abnormal root formation, and crown formation was normal (Fig. 1). The upper left first premolar was extracted and was observed to be, in all respects, a normal two-rooted tooth. The upper right