Reproducibility of Centric Relation Techniques by means of Condyle Position Analysis.

PURPOSE: The aim of this study was to determine the reproducibility of clinical centric relation (CR) registration techniques (bimanual manipulation, chin point guidance and Roth's method) by means of condyle position analysis. MATERIAL AND METHODS: Thirty two fully dentate asymptomatic subjects (16 female and 16 male) with normal occlusal relations (Angle class I) participated in the study (mean age, 22.6 ± 4.7 years). The mandibular position indicator (MPI) was used to analyze the three-dimensional (anteroposterior (ΔX), superoinferior (ΔZ), mediolateral (ΔY)) condylar shift generated by the difference between the centric relation position (CR) and the maximal intercuspation position (MI) observed in dental arches. RESULTS: The mean value and standard deviation of three-dimensional condylar shift of the tested clinical CR techniques was 0.19 ± 0.34 mm. Significant differences within the tested clinical CR registration techniques were found for anteroposterior condylar shift on the right side posterior (Δ Xrp; P ≤ 0.012); and superoinferior condylar shift on the left side inferior (Δ Zli; P ≤ 0.011), whereas between the tested CR registration techniques were found for anteroposterior shift on the right side posterior (ΔXrp, P ≤ 0.037) and superoinferior shift on the right side inferior (ΔZri, P ≤ 0.004), on the left side inferior (ΔZli, P ≤ 0.005) and on the left side superior (ΔZls, P ≤ 0.007). CONCLUSION: Bimanual manipulation, chin point guidance and Roth's method are clinical CR registration techniques of equal accuracy and reproducibility in asymptomatic subjects with normal occlusal relationship.

Undergraduate Students' Knowledge on Temporomandibular Disorders in Croatia.

The aim of this study was to evaluate Croatian undergraduate students' knowledge based on what they learned in the recent course, as well as the students' own judgment and opinions about geriatric dentistry education concerning temporomandibular disorders (TMDs) of the elderly. The study was carried out by means of a questionnaire administered in the last study year to students of the School of Dental Medicine, University of Zagreb and students of the Department of Dental Medicine at the School of Medicine, University of Rijeka. Th e questionnaire included questions about relevant specific knowledge on TMD, and statements related to their own opinion about geriatric dentistry education received during the study. Regarding students' knowledge related to TMDs, students from Rijeka gave more positive answers (p=0.012). Students from Rijeka gave more positive answers regarding physical therapy for treatment of TMD (p=0.004) and disc displacement and osteoarthritis as the most common disorders of the temporomandibular joint (p=0.031). Students from Zagreb were more unsatisfi ed with the skills in the field of geriatric dentistry (disagreed 57.45%) than students from Rijeka (45.83% had neutral standpoint and 37.50% agreed) (p=0.005). The level of the participants' knowledge pointed to the need of improving undergraduate dental teaching about the specific geriatric education, including knowledge about TMD.

Influence of the Hinge Axis Transfer Modality on the Three-Dimensional Condylar Shift Between the Centric Relation and the Maximum Intercuspation Positions.

PURPOSE: The purpose of the study was to determine whether the hinge axis registration and the transfer modality (facebow transfer vs. average mounting) from the subject to the articulator affect the three-dimensional condylar shift between the centric relation (CR) and the maximum intercuspation (MI) position. MATERIAL AND METHODS: The study was comprised of 32 fully dentate subjects (16 male and 16 female). Only the asymptomatic participants with normal occlusal relations (Angle class I) aged 20 - 33 (mean age 22.6 ± 4.7) met the inclusion criteria. Three-dimensional condylar shift (anteroposterior, superoinferior and mediolateral shift) between the centric relation position (CR) and the maximum intercuspation (MI) position was analyzed by means of Mandibular Position Indicator (SAM Prazisionstechnik GmbH, Muenchen, Germany). RESULTS: The average three-dimensional condylar shift was 0.13 ± 0.12 mm for facebow transfer and 0.22 ± 0.23 mm for average mounting. There were no statistically significant differences noted between genders. The results of the Mann-Whitney test showed statistically significant differences for anteroposterior and superoinferior condylar shift (P < 0.001). However, the difference in the mediolateral shift was not statistically significant. CONCLUSIONS: In order to find discrepancies within the three-dimensional condylar shift, facebow transfer proved to be more accurate than the average mounting in the semi-adjustable articulator. However, the average value of three-dimensional shifts of the condyle did not differ from normal values and they did not have clinical significance. Thus, both ways of transfer modalities (facebow transfer and average mounting) in asymptomatic subjects with normal occlusion can be considered reliable.

Alterations in the masseter muscle and plasma IL-6 level following experimentally induced occlusal interference and chronic stress--a study in rats.

This study was undertaken to examine the alteration of masseter and plasma interleukin-6 after inducing occlusal interference and chronic stress. Male Wistar rats were submitted to chronic stress procedure, exposed to occlusal interference, or exposed to both mentioned procedures. Whole blood and masseter tissue were collected to determine interleukin-6 level, measured by means of ELISA. Masseter pain was evaluated using the orofacial formalin test. Masseter interleukin-6 level was significantly higher in animals submitted to combination of occlusal interference and chronic stress than in the control group (p<0.05). There was positive and significant correlation between pain response and masseter interleukin-6 level (r=0.5741; p<0.0003). No significant differences in plasma interleukin-6 level were found between groups (p>0.05), as well as no correlation with pain (p>0.05). Combination of occlusal interference and chronic stress leads to strong local reaction characterized by high levels of masseter interleukine-6. High concentrations of muscle interleukin-6 and its correlation with pain point to inflammatory background of masticatory muscle pain.

Depression, somatization and anxiety in female patients with temporomandibular disorders (TMD).

The aim of this research was to determine the possible differences in degrees of depression, somatization and anxiety between the acute and chronic female patients with temporomandibular disorders (TMD), and whether these differences exist in healthy female patients. Ninety female patients were involved in this research; 60 of them were TMD patients of the Dental Polyclinic, while other 30 females came for a routine recall visit and had no problem related to TMD. Patients were aged 22 to 67 years, the average age being 38.5 +/- 12 years. All patients were asked to fill in the RDC/TMD protocol and three psychological tests (Emotions Profile Index, Somatization Scale and life Events Scale). Following the analysis of the RDC/TMD protocol and psychological tests, it was determined that the chronic female patients had higher depression and somatization scores in comparison with the acute patients (p < 0.01); the acute patients self-perceive higher levels of anxiety in relation to the control group; furthermore, the patients reporting higher levels of depression were more inclined to somatization and had experienced a greater number of stress events in the past six months. It is beyond doubt that patients suffering from the TMD's exhibit higher levels of depression, somatization and anxiety compared to the healthy ones, which proves that physiological factors may play a predisposing role in combination with reduced level of body tolerance to pain, and a decreased tolerance to stress.

Influence of chronic stress and oclusal interference on masseter muscle pain in rat.

This study aimed to investigate the individual effects of chronic stress and occlusal interference, as well as their combined influence on masseter muscle pain. Experiments were performed on 28 male Wistar rats. Animals were submitted to chronic stress procedure, exposed to occlusal interference, or exposed to both mantioned procedures. At the end of the procedure animals were submitted to orofacial formalin test, and nociceptive behavioral response was evaluated. Statisticaly significant difference of nociceptive behavioral response in chronicaly stressed rats and in the animals with occlusal interference in comparation to the control group were not obtained (p > 0.05). In contrast, nociceptive behavioral response was significantly increased in rats submitted to both of experimental procedures (p < 0.01). These findings suggest that only combination of occlusal interference and chronic stress influence masseter muscle pain.

Dental trauma in children and young adults visiting a University Dental Clinic.

The aim of the study was to present the distribution of traumatic dental injuries in the permanent anterior teeth in 447 consecutively selected patients in the age interval of 6 to 25 years treated at the Department of Paediatric Dentistry at the University Dental Clinic in Rijeka, Croatia, in the period from 2001 to 2006. Data on age, gender, number of injured teeth and type of injury were taken from the dental records. Of all 447 consecutively selected patients with traumatic dental injury 56.2% were boys and 43.8% were girls with a male/female ratio 1.28:1 (P < 0.01). The highest frequency of tooth injuries occurred among 10- to 13-years-old children. Among 30.6% of the cases, two or more teeth were injured (38.6% in boys and 21.4% in girls). Traumatic injuries affecting teeth in the upper jaw were more frequent (P < 0.001). The most commonly affected teeth were the maxillary central incisors (42.4% of right central incisors and 38% of left central incisors). The most frequent injury was enamel and dentin fracture without pulpal involvement (38.7%). In conclusion, more attention should be paid to preventive measures.

Changes of alveolar bone density around the abutment teeth in patients wearing removable partial dentures depending on Kennedy classification.

The aim was to study the influence of Kennedy classification on alveolar bone density changes around the abutment teeth of removable partial denture (RPD) clasp and rests. A total of 50 examinees of both gender wearing RPDs were included in the study. Changes of bone density around the abutment teeth were determined by an intraoral microdensitometry method. Standard retroalveolar radiographs were obtained twice: the first one at the RPD delivery and the second one after a period of 3 month of denture wearing. The copper stepwedge consisting of 5 steps (0.1-0.1 mm) was attached to the radiograph prior to exposure in order to calibrate it. Seven regions of interest (ROI) in different position close to the root of the abutment tooth were selected on each radiograph, all 10 pixels in size. Grey levels of each ROI were measured and were converted into equivalents of the copper stepwedge thickness using the third degree polynomial in order to compare the difference of bone density between the two radiographs. The results indicated that Kennedy classification had no significant influence on the change of bone density in RPD patients during first 3 month of RPD wearing (ANOVA: p > 0.05).