Treatment of severe temporomandibular joint clicking with botulinum toxin in the lateral pterygoid muscle in two cases of anterior disc displacement

A novel treatment procedure is introduced for severe clicking of the temporomandibular joint (TMJ) associated with anterior disc displacement (ADD), using injections with botulinum toxin (BTX-A) in the lateral pterygoid muscle (LP). It has been suggested that ADD may be caused, precipitated, or maintained by LP activity, but the role of the LP in the dynamics of the TMJ clicking is uncertain. The case report includes 2 women, followed with clinical examinations, TMJ imaging, and electromyography (EMG), in whom local anesthetics in the LP could abolish the clicking for several days. BTX-A block of the LP (30 U Botox, given twice under EMG guidance with 6-month interval) temporarily reduced the action of the muscle, but the clicking was permanently eliminated and did not return during the observation period of 1 year, and a small but distinctive positional improvement in the disc-condyle relationship was obtained. However, the precise mechanisms behind the favourable treatment outcome are unclear.     

The effect of finish line preparation and layer thickness on the failure load and fractography of ZrO2 copings

STATEMENT OF PROBLEM: To prevent tooth weakening or pulp irritation, there is a need for a minimally invasive method of preparing single anterior crowns. Restoration dimensions for reduced coping thicknesses or less invasive finish line preparations are required. PURPOSE: The purposed of this in vitro was to study investigate the fracture performance of high-strength zirconia copings, compare knife-edge margins with chamfer finish lines, and examine the effect of reducing the layer thickness from 0.5 mm to 0.3 mm. MATERIAL AND METHODS: Y-TZP zirconia copings were manufactured on brass dies of a maxillary central incisor. Forty copings, with 2 layer thicknesses (0.5 and 0.3 mm), and 2 finish line preparations (knife edge and chamfer; n=10) were cemented using a conventional glass ionomer cement and stored in distilled water at 37 degrees C for 24 hours. The copings were vertically loaded until fracture using a universal testing machine. Data were analyzed by 2-way ANOVA (alpha=.05). Fractographic examination was performed using scanning electron microscopy and confocal laser scanning microscopy. RESULTS: A significantly higher mean failure load was measured for knife-edge (0.5 mm, 1110 +/-175 N; 0.3 mm, 730 +/-160 N) versus chamfer (0.5 mm, 697 +/-126 N; 0.3 mm, 455 +/-79 N) preparations (P<.001), and for 0.5-mm versus 0.3-mm thickness layers (P<.001). CONCLUSIONS: Knife-edge preparations present a promising alternative to chamfer finish lines; the fracture load required for knife-edge preparations was 38% greater than that required for chamfer preparations, regardless of coping thickness. Reducing the thickness of a single crown coping from 0.5 to 0.3 mm resulted in a 35% reduction in fracture load required for either preparation type.     

Tooth avulsion and replantation — A review

Abstract The major causes of post-replantation tooth loss are inflammatory root resorption and root resorption associated with ankylosis. Recent studies have concentrated on delineating the cellular interactions in the pulp and periodontium in order to more fully understand the various factors affecting the prognoses of such teeth. The aim of this report is to discuss the nature of the pathology responsible for tooth loss following avulsion and to review recent replantation and attachment studies.     

Cementum hypoplasia in teeth affected by juvenile periodontitis

The cemental surface of teeth affected by juvenile periodontitis was examined using scanning electron microscopy. Molars affected by chronic marginal periodontitis and healthy molars were included as controls. The entire mesial root of teeth affected by juvenile periodontitis showed extensive areas of cementum hypoplasia with exposed dentinal tubules. The hypoplasias were found also on the infracrestal part of the root indicating that they had not been caused by exposure to the oral environment or by any treatment. Cementum hypoplasias were not found in any teeth from the control material. The impaired periodontal attachment in the hypoplasia may facilitate penetration by the special motile bacteria which have been found in plaque from teeth with juvenile periodontitis. Based on the findings in the present study and the hereditary background of juvenile periodontitis it was suggested that development of the disease is initiated by a hereditary developmental disturbance of the cementum.     

One-year prospective three-center study comparing the outcome of a "soft bone implant" (prototype Mk IV) and the standard Brånemark implant

Background: Oral implant treatment ad modum Brånemark has been used for decades in the rehabilitation of edentate and partially dentate patients. Posterior jaw regions frequently exhibit bone of poor texture, and it is often difficult to obtain primary stability. Thus, it may prove beneficial to deviate from the original protocol and to use implants with a modified design, for example, with a slightly tapered geometry. Purpose: The purpose of the investigation was to compare the early behavior of a modified (prototype Mk IV, Branemark System, Nobel Biocare AB, Gothenburg, Sweden; test) implant with that of the standard Brånemark implant (control) in regions of mainly type 4 bone. Materials and Methods: Three Swedish centers participated, and a total of 44 patients were treated with oral implants for 39 maxillas and 5 mandibles. The study focused on the most distal right and left implant sites (88 implants), which were randomized to receive either a test or a control implant. Various parameters were recorded, such as registered insertion torque (OsseoCare, Nobel Biocare AB), wobbling during insertion, primary and secondary stability (as measured with resonance frequency), and marginal bone loss. The implants were followed up for 1 year. Results.: The test implant more frequently required a higher insertion torque and showed a significantly higher primary stability than the control implant. This difference in stability leveled out over time, and test and control implants exhibited similar secondary stability at abutment operation and at the 1‐year visit. Wobbling during insertion was rarely recorded for either of the implant designs. The 1‐year cumulative success rate was 93.1% for test implants and 88.4% for control implants. Conclusions: The modified implant design resulted in an increased primary stability, which may be important when placing implants in jaw regions of type 4 bone. However, independent of the achieved primary stability, successful implants tended to approach similar secondary stability in the two designs tested.     

Mercury inductions in persons with subjective symptoms alleged to dental amalgam fillings

This study was carried out to determine whether health disturbances alleged to mercury release from dental amalgam fillings, i.e. "amalgam disease", may be caused by an increased sensitivity to mercury (Hg). In the form of a double-blind test, 39 volunteers who themselves suspected "amalgam disease" inhaled small doses of mercury vapour (0.6-10 microg) or pure air in a random sequence. After the induction procedure, the test persons assessed whether they reacted or not, i.e. experienced increased illness or not. The test persons also registered the daily intensity of their various symptoms. Calculated on the whole population, there was no statistically significant difference between the number of reactions after inhalation of mercury vapour compared with after inhalation of air. Two subjects, however, reacted significantly more often to mercury vapour than to air. The results do not support that short-term exposure to low doses of Hg vapour in general promotes clinical illness in subjects who themselves suspect "amalgam disease". The deviating reactions presented by two test persons, however, may support the theory that occasional individuals can be sensitive to very low doses of Hg.     

Psychosocial and dental factors in the maintenance of severe dental fear

The aim was to study the relationship between psychosocial factors and dental status in adult subjects with severe dental fear (DF). A consecutive sample of 148 adults (mean age 36.1 yrs, range 21-69 yrs) referred for dental fear treatment was investigated using an intake questionnaire on dental attendance and history, psychometric questionnaires on dental fear, general anxiety and depression and a radiographic examination. The subjects had a mean DFMT (Decayed, Filled, Missed Teeth) score of 18.6 (SD = 5.6). A deterioration in dental status defined as the presence of root remnants was present in 57% of the subjects and was related to the negative consequences of dental fear, general anxiety and depression. Most subjects (84%) reported clinical levels of general anxiety and 46% reported clinical levels of depression. In conclusion, subjects with severe DF often suffer from psychosocial consequences and distress.This is even more marked if their dental status has deteriorated.The findings support a biopsychosocial vicious circle understanding of the maintenance of DF.     

Anomalies of tooth formation in hypohidrotic ectodermal dysplasia

OBJECTIVE: The X-linked hypohidrotic ectodermal dysplasia (HED) is the most common type of ectodermal dysplasia. The clinical identification of possible heterozygous females can be difficult because of the varying degrees of clinical signs caused by X-chromosome inactivation. This study is the first to elaborate on anomalies of tooth formation found in a group of hemizygous males and heterozygous females with known ED1 mutations. These tooth anomalies may be used as dental biomarkers for heterozygous females, enabling an earlier diagnosis, and therefore, better treatment and genetic counselling. METHODS: Anomalies of tooth formation were examined using panoramic radiographs, dental casts and oral photographs in hemizygous males and heterozygous females who were identified by molecular genetic analysis. The results were compared to existing controls and normative data. RESULTS: All affected males had multiple missing permanent teeth and tooth malformations. The heterozygous females had a significantly higher frequency of agenesis of permanent teeth compared to normative data. The heterozygous females had an increased prevalence of tooth malformations and reduced tooth size, especially in the mesiodistal dimension. CONCLUSIONS: We conclude that observed anomalies of tooth formation may be used as dental biomarkers in the clinical identification of potentially heterozygous females.     

Repair of periodontal tissues In vivo and in vitro

Repair of experimental cavities in dental roots and of periodontal wounds was studied in vivo and in vitro. Incisors from monkeys were extracted and experimental cavities were made in the roots. The teeth were either replanted immediately or cultured for 1-12 weeks in tissue culture medium. After 8 weeks the tissue reaction around the replanted teeth was evaluated on demineralized histological sections and undecalcified freeze-sections incubated for histochemical demonstration of certain enzymes. The cultured teeth were evaluated on decalcified histological sections. In the experimental cavities of the replanted teeth reparative cementum was found. It was frequently separated from the denuded dentin while a firm attachment was always established to the intermediate cementum and dental cementum at the periphery of the cavities. The reparative cementum was also firmly attached to some small areas on the exposed dentin surface where resorption had taken place. The activity of alkaline and acid phosphatase was lower in the connective tissue in the experimental cavities than in the surrounding PDM, suggesting an incomplete regeneration of the periodontal membrane in these areas. A loose connective tissue devoid of demonstrable collagen fibers was found in the cavities in vitro. The reparative cementum did not fill the experimental cavities in the replanted teeth. The alveolar bone extended into the experimental cavities and made the width of the PDM normal also in the experimental cavities. Epithelial and endothelial cells were numerous in the connective tissue separating the reparative cementum from the alveolar bone in the experimental cavities. It is possible that they contribute to the integrity of the PDM and prevent resorption of the dental root.