Jaw elevator silent periods in complete denture wearers and dentate individuals.

Functional meaning and underlying mechanisms of jaw elevator silent period (SP) have still not been completely understood. Since complete denture wearers (CDWs) have no periodontal receptors in their jaws, the aim was to examine SPs in CDWs and to compare it with dentate individuals (DIs). Thirty six DIs (skeletal/occlusal Class I) and 24 eugnath CDWs participated. EMG signals were registered using the EMGA-1 apparatus from the left and the right side anterior temporalis (ATM) and masseter muscles (MM). Ten registrations of an open-close-clench (OCC) cycle were obtained for each individual. DIs had the average latency between 12.5 and 12.9 ms and always one single short inhibitory pause (IP) with complete inhibition of motoneurons (20.1-21.1 ms). On the other hand, in CDWs various types of SPs emerged: single or single prolonged SPs, double SPs, SPs with three IPs, periods of depressed muscle activity following the first, or the second IP, SPs with relative inhibition of motoneurons or even in several registrations the SP was missing. Unless more than one IP emerged, complete duration of inhibitory pauses (CDIP) was measured. CDIP varied from 37.17 to 42.49 ms. Average latencies were from 16.22 to 16.76 ms. Based on the results of this study it is obvious that both, the duration and the latencies were significantly longer in CDWs than in DIs (p<0.05), which can be explained by different mechanisms responsible for the muscle reflex behaviour.

The influence of age and dental status on elevator and depressor muscle activity.

The objective of this study was to determine whether the muscle activity at various mandibular positions is affected by age and dental status. Thirty edentulous subjects (E), 20 young dentate individuals (G1) and 20 older dentate individuals (G2) participated in this study. Surface electromyographic (EMG) recordings were obtained from the anterior temporal (T), masseter (M) and depressor muscles (D). Muscle activity was recorded during maximal voluntary contraction (MVC), maximal opening (O(max)) and in six different mandibular positions. One way anova and the Bonferroni tests were used to determine the differences between groups. Significant differences between the three tested groups were found at MVC and O(max) for all examined muscles (P < 0.001). The differences in muscle activity in dentate subjects of different age were found in protrusion for depressor muscles (P < 0.05) and in lateral excursive positions for the working side temporal (P < 0.05) and non-working side masseter and depressor muscle (P < 0.05). There was a significant effect regarding the presence of natural teeth or complete dentures in protrusion and maximal protrusion for all muscles (P < 0.05) and in lateral excursive positions for non-working side temporal (P < 0.05) and working side masseter muscle (P < 0.05). Muscle activity at various mandibular positions depends greatly on the presence of the prosthetic appliance, as edentulous subjects had to use higher muscle activity levels (percentages of maximal EMG value) than age matched dentate subjects in order to perform same mandibular movement. Different elevator muscles were preferentially activated in the edentulous subjects when compared with dentate group in lateral excursive positions of the mandible. The pattern of relative muscle activity was not changed because of ageing.

A survey of treatment outcomes with removable partial dentures.

The patient's satisfaction with removable partial denture (RPD) therapy has become an increasingly important factor in prosthetic treatment. This study examined patients' satisfaction with RPDs in relation to some socio-economic variables, patients' habits of wearing and cleaning RPDs, comfort of wearing RPDs and different RPDs characteristics. A questionnaire was devised for the purpose. Two hundred and five patients were required to assess satisfaction with RPDs. They graded RPDs, depending on the level of satisfaction, on scale ranging from 1 to 5. A dentist determined Kennedy classification, material and denture support, denture base shape, number of missing teeth and evaluated denture construction. Majority of the patients were satisfied with the prosthesis. The patients of a higher education level gave lower grades (P < 0.05) to aesthetics of maxillary RPDs. Almost half of the patients were wearing RPDs during the day. Most of the patients cleaned RPDs three times a day. A significant difference was found between the patients' grades for comfort of wearing mandibular RPDs and number of missing teeth and between hygiene of mandibular RPDs and habits of cleaning them. Majority of the patients treated with RPDs were satisfied with the prosthesis. Dissatisfaction was related to mastication, esthetics, number of missing teeth and maintenance of oral hygiene.

The influence of war stress on the prevalence of signs and symptoms of temporomandibular disorders.

The aim of this study was to determine the prevalence of signs and symptoms of temporomandibular disorders in patients with post-traumatic stress disorder (PTSD) occurring as a consequence of exposure to war stress. The examined group consisted of 100 male subjects, aged from 25 to 50 years, who had taken part in the War in Croatia, and in whom PTSD had previously been diagnosed. The control group comprised 100 subjects, without PTSD, of the same sex and age group, who had not taken part in the War. A functional evaluation of the stomatognathic system was performed using the Helkimo Anamnestic and Clinical Dysfunction Index. Eighty-two per cent of the group with PTSD had at least one symptom, and 98% at least one sign of dysfunction. Eight per cent reported mild symptoms and 74% severe symptoms. Twenty-eight per cent showed mild clinical signs, 22% had signs of moderate, and 48% of severe dysfunction. Twenty-four per cent of the control group of subjects had at least one symptom, and 52% at least one clinical sign of dysfunction. Twenty-two per cent reported mild and 2% severe symptoms. Mild clinical signs of dysfunction were found in 50% of subjects in the control group, moderate in 2% and none exhibited severe clinical signs. It is concluded that correlation exists between war stress and temporomandibular disorders.

The patient's and the therapist's evaluation of complete denture therapy.

A total of 222 patients were studied. In a questionnaire patients graded their complete dentures of different age and quality, depending on the level of satisfaction, using the modified analogue-visual scale from 1 to 5. The dentist assessed the same dentures, as well as the denture bearing area. The patients' assessments were surprisingly high, the grades were bigger than the therapist's (p < 0.05), but in disappointed patients the grades were smaller than the therapist's (p < 0.05). It seems that the dentist is more critical in assessments than the patient. No significant difference existed between chewing and denture stability and between stability and the comfort of wearing lower full denture (p > 0.05). Unstable denture aggravates chewing and causes pain and discomfort on the bearing area. It seems that subjective factors in patients, expectations of the denture or the number of previous dentures play a role in satisfaction, not only the quality of denture bearing area and the quality of a denture.

The satisfaction with the removable partial denture therapy in the Croatian adult population.

Little is known about the outcomes of treatment and patient's satisfaction with removable partial dentures in adult Croatian population. Therefore patient's satisfaction with their partial dentures in relation to some socio-economic variables was studied. Patient's satisfaction with denture retention, speech, aesthetics, comfort of wearing dentures, chewing ability was also studied in relation to different denture classification, construction, material, denture base shape (major connectors), denture support and the number of missing teeth. A total of 165 patients, 59 males and 105 females between 38 and 87 years took part in this study. A questionnaire, devised for a purpose of the study, was divided into three parts. In the first part, patients answered questions about age, gender, marital status, education, general health, socio-economic status, self-supporting life, period of tooth loss and number of previous denture experiences and in the second part, patients graded their partial dentures, depending on the level of satisfaction, by using a scale from 1 to 5. In the third part a dentist determined Kennedy classification and their modifications, denture material and denture support, denture base shape and the number of missing teeth and graded a denture construction. Influence of these factors on patient's satisfaction was analyzed. A majority of the examined patients were satisfied with the partial prosthesis, but a small amount of dissatisfaction existed. More then half of them scored all the examined parameters to the best score category. Considering chewing with lower partial dentures, women were more satisfied than men (p < 0.05). Patients with more missing teeth gave lower grades for the comfort of wearing dentures (p < 0.05). Patients of higher education gave lower grades (p < 0.05) for the aesthetics. Patients were not satisfied with speech if the dentist graded a construction of a lower partial denture low (p < 0.05). Dissatisfaction was related to mastication, aesthetics, number of missing teeth and ability of speech. These findings can aid a clinician in discussing a treatment plan and help a patient understand the risk of dissatisfaction in the presence of certain factors.

Evaluation of the precision of dimensional measurements of the mandible on panoramic radiographs.

The purpose of this study was to evaluate the precision of dimensional measurements of the mandible on orthopantomographic images and thus to evaluate their dimensional reliability. Different distances denoted by metal markers were measured on 25 dry mandibles. The same mandibles were then positioned in an orthopantomographic machine, and radiographic images of them were made. Measurements of the same distances were made on the panoramic images and then compared with the results of the measurements on the dry mandibles. All results were statistically analyzed. The results showed significant difference between the magnification factor listed by the manufacturer and calculated magnification factors, the latter being closer to 1.00. The study also showed that linear measurements made on only one side of the panoramic image of a mandible were very close to the actual dimensions of the dry mandible, whereas measurements that extended across the midline of the mandible were greatly enlarged because of large magnification factors; therefore, such measurements should not be made.

Dimensional measurements on the human dental panoramic radiographs.

The objective of this study was to evaluate the precision of the horizontal and vertical linear dimensional measurements on orthopantomographic images. Different horizontal and vertical distances denoted by metal markers were measured on 25 dry mandibles. The same mandibles were then positioned in an orthopantomographic machine and their radiographic images were made. Measurements of the same distances were repeated on the panoramic images and compared to the results of the measurements on the dry mandibles. All results were statistically analyzed. The results showed significant difference between the magnification factor listed by the manufacturer and the calculated magnification factors, the latter being closer to 1.00. The study also showed that linear measurements made only on one side of panoramic images of mandibles were close to actual dimensions of dry mandibles, while the measurements which extended across the midline of mandibles were greatly enlarged due to large magnification factors.

The response of human premolars to cyclic loading.

The aim of the study was to obtain data on the dynamic strength of both intact and prepared premolars for partial veneer crowns. Cyclic loading was performed in a modified Amslers high-frequency pulsator with varying force (between 400 and 1400 N). The greatest dynamic strength was exhibited by the intact samples. The greater the load the fewer the cycles necessary to fracture the tooth. A statically significant difference was found (P < 0.05) between the magnitude of cyclic loads and the different types of specimens tested.

A study of the occlusal plane orientation by intra-oral method (retromolar pad).

Reliability of the intra-oral method which orientates the occlusal plane to terminate at the upper level of the retromolar pad was studied. Thirty individuals all with natural teeth and 34 complete denture wearers participated in the study. Stone casts were mounted in the S.A.M. 2 articulator by a quick mount face bow transfer. The angle between the occlusal plane and the articulator horizontal plane was measured in both groups. The angle was 9.42 degrees +/- 4.1 degrees in dentate individuals and 8.53 degrees +/- 2.8 degrees in complete denture wearers. No statistically significant difference was found between the groups (t = 0.72, P > 0.05). Therefore, the method can be advocated for a wide clinical use, as it is a simple method and places the artificial occlusal plane very close to the position of the natural plane of occlusion.

[Influence of aging and the loss of teeth on some variations of TMJ]. / Utjecaj zivotne dobi i stupnja ozubljenosti na neke parametre temporomandibularnog zgloba.

Many authors consider that the contours and dimensions of TMJ continue to be reshaped and remodeled even after the period of growth and development is complete, in response to changing mechanical stresses under influence of aging, abrasion and the loss of the teeth. Therefore, the aim of this study was to find out if aging and the loss of teeth make any influence on TMJ. The sample consisted of 80 dry skulls and their mandibles. The following parameters were measured: 1A (AB) the distance from the lateral ending of petrotympanic fissure to the intersection of petrotympanic and petrosquamosus fissure, 1B (BC) the distances from the intersection of petrotympanic and petrosquamosus fissure to the most prominent part of the articular eminence, 1C (AC) the distance from the lateral ending of petrotympanic fissure to the most prominent part of articular eminence and 2 (h) the depth of the mandibular fossa. Measured values were analysed in connection with sex, age, the different percentage of the remaining teeth and the left or the right side. There was no significant difference at the probability level of 95%, nor for the left and the right side, neither for the different age groups, sex and the different percentage of the remaining teeth (p greater than 0.05). Still, it is obscure the existence and the changes in TMJ when the growth is completed. It is necessary to study this problem on the bigger sample and the new methods as CT and artroscopy could be helpful.

[Angle between occlusal plane and horizontal plane of articulators with quick mounting face bow]. / Nagib protetske plohe u odonosu na horizontalu artikulatora s obraznim lukom za brzu montazu.

Correct determination of the occlusal plane is important for estetic, phonetic and masticatory function of the denture. As many different criterias are used in clinical practice to determine the occlusal plane on the wax rims, the aim of this study was to find the angle between the occlusal plane and the horizontal plane in the articulators with the quick mounting face bow. The measurements were made on the casts of 30 eugnath individuals with at least 28 natural teeth, mounted in S.A.M. articulator through the transfer with the Quick mounting face bow, in the position of maximum intercuspation. Measurements were made with a precise caliper and were transferred to the calibrated paper. The angles were measured between the occlusal plane and the horizontal plane. The angle is 9.42 degrees +/- 4.1 degrees in the population of this country. This result can be helpful to determine the occlusal plane or to control if the occlusal plane, determined by the other methods is in the correct position in articulator.