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PubMed2003

Enamel matrix derivative (Emdogain) for periodontal tissue regeneration in intrabony defects.

BACKGROUND: Periodontitis is a chronic infective disease of the gums caused by bacteria present in dental plaque. This condition induces the breakdown of the tooth supporting apparatus until teeth are lost. Surgery may be indicated to arrest disease progression and regenerate lost tissues. Several surgical techniques have been developed to regenerate periodontal tissues including guided tissue regeneration (GTR), bone grafting (BG) and the use of enamel matrix derivative (EMD). EMD is an extract of enamel matrix and contains amelogenins of various molecular weights. There is evidence to show that amelogenins are involved not only in enamel formation, but also in the formation of the periodontal attachment during tooth formation. OBJECTIVES: To test the efficacy of EMD in comparison with open flap debridement, GTR and various BG procedures for the treatment of intrabony defects. SEARCH STRATEGY: We searched the Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. Several journals were handsearched. No language restrictions were applied. Authors of randomised controlled trials (RCTs) identified, personal contacts and the manufacturer were contacted to identify unpublished trials. Most recent search: January 2003. SELECTION CRITERIA: RCTs on patients affected by periodontitis having intrabony defects treated with EMD compared with open flap debridement, GTR and various BG procedures with at least one year follow up. The outcome measures considered were: tooth loss, changes in probing attachment levels (PAL), pocket depths (PPD), gingival recessions (REC), marginal bone levels on intraoral radiographs and postoperative infections. DATA COLLECTION AND ANALYSIS: Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in duplicate and independently by two reviewers. Results were expressed as random effect models using weighted mean differences for continuous outcomes and relative risk for dichotomous outcomes with 95% confidence interval (CI). Heterogeneity was investigated including both clinical and methodological factors. MAIN RESULTS: No difference in tooth loss was observed. A meta-analysis including eight trials showed that Emdogain treated sites displayed statistically significant PAL improvements (mean difference 1.3 mm, 95%CI: 0.8 to 1.8) and PPD reduction (1 mm, 95%CI: 0.5 to 1.4) when compared to flap surgery. Comparing Emdogain with GTR (six trials), GTR showed a statistically significant reduction of PPD (0.6 mm) and increase of REC (0.5 mm). No difference in postoperative infections was observed. REVIEWER'S CONCLUSIONS: Emdogain is able to significantly improve PAL levels (1.3mm) and PPD reduction (1mm) when compared to flap surgery, however these results may not have a great clinical impact, since it has not been shown that more periodontally compromised teeth could be saved. There was no evidence of clinically important differences between GTR and Emdogain.

Alveolar Bone Loss↗
PubMed2005

Enamel matrix derivative (Emdogain) for periodontal tissue regeneration in intrabony defects.

BACKGROUND: Periodontitis is a chronic infective disease of the gums caused by bacteria present in dental plaque. This condition induces the breakdown of the tooth supporting apparatus until teeth are lost. Surgery may be indicated to arrest disease progression and regenerate lost tissues. Several surgical techniques have been developed to regenerate periodontal tissues including guided tissue regeneration (GTR), bone grafting (BG) and the use of enamel matrix derivative (EMD). EMD is an extract of enamel matrix and contains amelogenins of various molecular weights. Amelogenins are involved in the formation of enamel and periodontal attachment formation during tooth development. OBJECTIVES: To test whether EMD is effective, and to compare EMD versus GTR, and various BG procedures for the treatment of intrabony defects. SEARCH STRATEGY: We searched the Cochrane OHG Trials Register, Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE. Several journals were handsearched. No language restrictions were applied. Authors of RCTs identified, personal contacts and the manufacturer were contacted to identify unpublished trials. Most recent search: May 2005. SELECTION CRITERIA: RCTs on patients affected by periodontitis having intrabony defects of at least 3 mm treated with EMD compared with open flap debridement, GTR and various BG procedures with at least 1 year follow up. The outcome measures considered were: tooth loss, changes in probing attachment levels (PAL), pocket depths (PPD), gingival recessions (REC), bone levels from the bottom of the defects on intraoral radiographs, aesthetics and adverse events. The following time-points were to be evaluated: 1, 5 and 10 years. DATA COLLECTION AND ANALYSIS: Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in duplicate and independently by two authors. Results were expressed as random-effects models using mean differences for continuous outcomes and risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CI). It was decided not to investigate heterogeneity, but a sensitivity analysis for the risk of bias of the trials was performed. MAIN RESULTS: Ten trials were included out of 29 potentially eligible trials. No included trial presented data after 5 years of follow up, therefore all data refer to the 1-year time point. A meta-analysis including eight trials showed that EMD treated sites displayed statistically significant PAL improvements (mean difference 1.2 mm, 95% CI 0.7 to 1.7) and PPD reduction (0.8 mm, 95% CI 0.5 to 1.0) when compared to placebo or control treated sites, though a high degree of heterogeneity was found. Significantly more sites had < 2 mm PAL gain in the control group, with RR 0.48 (95% CI 0.29 to 0.80). Approximately six patients needed to be treated (NNT) to have one patient gaining 2 mm or more PAL over the control group, based on a prevalence in the control group of 35%. No differences in tooth loss or aesthetic appearance as judged by the patients were observed. When evaluating the only two trials at a low risk of bias in a sensitivity analysis, the effect size for PAL was 0.6 mm, which was less than 1.2 mm for the overall result. Comparing EMD with GTR (five trials), GTR showed a statistically significant increase of REC (0.4 mm) and significantly more postoperative complications. No trials were found comparing EMD with BG. AUTHORS' CONCLUSIONS: One year after its application, EMD significantly improved PAL levels (1.2 mm) and PPD reduction (0.8 mm) when compared to a placebo or control, however, the high degree of heterogeneity observed among trials suggests that results have to be interpreted with great caution. In addition a sensitivity analyses indicated that the overall treatment effect might be overestimated. The actual clinical advantages of using EMD are unknown. With the exception of significantly more postoperative complications in the GTR group, there was no evidence of clinically important differences between GTR and EMD.

Alveolar Bone Loss↗
PubMed1998

Food-holding and -biting behavior in human subjects lacking periodontal receptors.

Previous studies have suggested that information provided by periodontal mechanoreceptors is particularly important for the fine motor control of the mandible, i.e., when humans hold and carefully manipulate food particles between the teeth with low biting forces. In the present study, we further evaluated this hypothesis by comparing the performance of three age- and gender-matched groups of subjects for which the integrity of the periodontal sensory apparatus differed. Specifically, the subjects had either natural teeth (natural group), dental prostheses supported by oral mucosa (denture group), or dental prostheses supported by osseointegrated implants (implant group). Each subject was instructed to hold half a peanut between the upper and lower central incisors for ca. 3 sec, and then to split it. The force applied by the anterior teeth was continuously monitored by a transducer-equipped bar on which the morsel rested. While the peanut was held, the force generated by subjects in the denture and implant groups was more variable and averaged four times that generated by subjects in the natural group. The peanut was split by a distinct, rapid ramp-increase in force that was similar for all three groups. In subjects lacking periodontal receptors, the morsel frequently escaped from the incisal edges during both phases of the task. The results demonstrate a marked disturbance in the control of precisely directed, low biting forces in subjects lacking periodontal receptors and suggest that the receptors play a significant role in the specification of the level, direction, and point of attack of forces used to hold and manipulate food between the anterior teeth. Moreover, other types of mechanoreceptors can not fully compensate for the loss of periodontal receptors.

Aged↗
PubMed2003

Artifacts from dental casting alloys in magnetic resonance imaging.

The potential advantage of magnetic resonance imaging (MRI) has been limited by artifacts due to the presence of metallic materials. For quantitative evaluation of the magnitude of artifacts from dental casting alloys and implant materials in MR imaging, 11 dental casting or implant materials were imaged by means of 1.5 T MRI apparatus with three different sequences. Mean and standard deviation of water signal intensity (SI) around the sample in the region of interest (1200 mm(2)) were determined, and the coefficient of variation was compared for evaluation of the homogeneity of the SI. A variety of artifacts with different magnitudes was observed. Only one of the samples, composed mainly of Pd, In, and Sb, showed no artifacts in all imaging sequences. We concluded that selection of specific dental casting alloys according to their elemental compositions could minimize the metal artifacts in MRI; however, titanium alloys currently pose a problem with respect to causing MRI artifacts.

Alloys↗
PubMed1977

[The morphologic relation between the temporomandibular joint and other components of the masticatory apparatus in catarrhine simians and humans].

The articular temporo-mandibular structures and their osseous and dental environment were studied in some catarhinians Simians (Cynomorphs and Anthropomorphs) and some representatives of the human lineage. The study of measurable and descriptive characters showed a relative stability of the temporo-mandibular joint compared to the dynamism of the other components of the masticatory system. The functional specificity of the actual human temporo-mandibular joint seemed to be tightly associated to the main processes leading toward human evolution (facial regression, increase of the cranial capacity). On the other hand, this study casts some doubts regarding the utilization of Primates for experiments in this field.

Animals↗
PubMed1976

The biosynthesis and secretion of precursor enamel protein by ameloblasts as visualized by autoradiography after tryptophan administration.

The incorporation of 3H-tryptophan into the inner enamel epithelium of newborn mouse incisor tooth organs has been studied in situ by light and electron microscopic autoradiography to determine the sites and kinetics of biosynthesis, migration, and secretion of precursor enamel protein during newborn mouse incisor tooth formation maxillary and mandibular incisor tooth amelogenesis was studied 5, 30, 60, 120, 240 minutes and 24 hours following the intraperitoneal injection of 3H-tryptophan. By 5 minutes, 40% of the total silver grains associated with the secretory ameloblasts were localized over the rough endoplasmic reticulum and 50% of the silver grains were localized over the Golgi apparatus. By 30 minutes, silver grains were observed predominately over condensing vacuoles and secretory granules within the forming Tomes' processes, and were also localized over the extracellular "granular" pre-enamel matrix. The enamel proteins were synthesized on membrane-bound polysomes, transferred within the cisternae of the rough endoplasmic reticulum and then accumulated in the inner saccules of the Golgi apparatus. The enamel proteins were than packaged in condensing vacuoles which subsequently became secretory granules which migrated to the lateral and apical secretory regions of the forming Tomes' processes. It was concluded from these in vivo studies that enamel protein were synthesized and subsequently secreted within 30 minutes. The initially secreted precursor enamel protein was localized over a material which demonstrated a granular or stippled ultrastructure. The labeled protein then was localized over the amorphous enamel matrix per se which contained the forming calcium hydroxyapatite crystals. We assumed, therefore, that there are two different ultrastructural forms of 3H-tryptophan containing extracellular enamel proteins and suggest that the granular or "stippled" form represents newly secreted precursor enamel protein.

Ameloblasts↗
PubMed1978

[Some studies on the ability appreciation of dental handpieces (author's transl)].

Dental handpieces are usually used for cutting teeth instruments of dental treatments. But as ability appreciation of cutting instruments are widely influenced with cutting tools and then these studies have scarcely been reported until now. This paper shows the one method of the ability appreciation of handpieces which are used for test bur as the cutting tools. Test apparatus used for ability appreciation are manufactured for trial as the same way as the dental treatments and experiments of handpiece are carried out. Handpiece test specimens are standard type (air bearing type) made by own country as basic characteristics and then compering with the ability of the type differences, standard, miniature, supertorque and air bearing type made by foreign country are experimented. These results of tests are examined the influence of service air pressure and load speed to be bases on the relation between push load revolution of test burs. And then equivalent efficiency of the works of handpieces are discussed for the experimental results of these characteristics.

Air↗
PubMed1997

Mandibular distraction osteogenesis. Preliminary results of an animal study with a dentally fixed distraction device.

Lengthening of the human mandible by distraction osteogenesis has become an accepted treatment for correction of severe mandibular disto-basal discrepancies in recent years. This usually entails the deployment of extra-orally located distraction devices. This type of device often causes conspicuous scarring. To avoid this scarring, an intra-oral device is to be developed. In the present animal study, 2 "Troll" mini-pigs and 2 "Yucatan" micro-pigs were fitted with a new solely dentally fixed orthodontic device for mandibular distraction osteogenesis. Following bilateral osteotomy in the dentigerous area of the mandibular body and a latent period of 2 to 7 days, the apparatus was activated 1 mm per day. Within a period of 9 days, a mandibular lengthening of 9 mm was reached. This situation was retained using the distraction device for 6 weeks. After removal of the apparatus, there followed another 6-week period of consolidation. During the experiment, the callus and bone formation and potential dental and periodontal reactions were radiologically examined and underwent histological examination at the end of the experiment. Twelve weeks after the mandibular lengthening, the osteogenesis in the distraction areas was complete. No destructive processes were recognizable, either at the roots or at the periodontium of the teeth near the osteotomy gap. Lengthening of the mandibular body using distraction osteogenesis with the help of a solely dentally fixed distraction device is thus feasible and can, in the future, become the appropriate treatment in the correction of severe mandibular deficiency.

Animals↗
PubMed1982

The creep compliance of dental amalgam in the stress range of 20-80 MPa.

The continuous compressive creep curves of four distinct types of one-week-old dental amalgam were monitored for one day on a specially designed mini-specimen creep apparatus. Creep conditions included three different applied constant stress levels (20, 40, and 80 MPa), and temperatures ranging from 0 degrees C to 60 degrees C. To compensate for changing dimensions at high creep strains, the data was converted to terms of compressive creep compliance. For all types of dental amalgam, compressive creep increased both with increased applied stress and with increased test temperature. The two high copper systems evaluated appear to approach a steady-state creep condition up to the highest temperatures tested, but the two conventional amalgams appear to change their creep exponent precipitously at temperatures above 45 degrees C.

Dental Amalgam↗
PubMed1986

Studies of individuals with orofacial discomfort complaints. An investigation of a group of patients who related their sufferings to effects of dental materials and constructions.

This thesis is based on seven studies. The aims of these studies were to investigate a series of consecutive patients with orofacial and general sensations and complaints of discomfort, which the patients assumed to be caused by galvanic currents created by metallic dental fillings and restorations, as well as contact allergy to both metallic and non-metallic substances in dental materials. Studies I and II described the patients' symptoms and complaints, as well as the clinical findings of many odontological and medical examinations. A widely varying symptom panorama and numerous clinical findings, both oral and general, have been found which could not be explained by a single etiological factor. A combination of many factors, such as general health problems, side effects of medication, psychosocial problems, including stressful life events and complications due to the chronicity of the pain formed the background to the oral and general complaints of these patients. The salivary and microbiological conditions and patch test results were presented in studies III and IV. The saliva flow rate, pH and cariogenic bacteria level as well as contact allergy to metallic and non-metallic substances known as allergens, were not significantly different, but buffer capacity and saliva conductance did differ. A laboratory investigation of the corrosion behaviour of dental amalgams and gold alloys in natural saliva and saline solutions was performed (Study V) and the corrosion state of dental amalgam fillings and constructions was examined (Study VI). Special laboratory and clinical methods and apparatus were constructed and used. No differences between electrode potentials of the amalgam fillings and constructions in patients with and without orofacial discomfort complaints were measured. Study VII presented an analysis of the outcome of the treatments applied. The treatment was based on each patient's symptoms and signs and probable diagnosis. Besides conventional dental, stomatognathic and medical treatment, metallic constructions were removed in 54% of the patients. The initial treatment result was favourable in 80% but recurrences were frequent. It was concluded that these patients need a careful oral examination and dental treatment of observed local pathosis and defects of dental constructions, but removal of metallic fillings and constructions should be avoided when not indicated. Many of these patients require medical consultation and treatment, and collaboration between dentist and the physician is recommended.

Adult↗
PubMed1994

In vitro quantitative assessment of generalized wear of dental composites.

The purpose of this paper was to compare generalized wear resistance of eleven proprietary posterior dental composites and one amalgam using a recently developed in vitro wear testing apparatus. Upon completion of the in vitro wear testing process the wear area of occlusal surface was replicated and the depth of enamel exposed at the cavity margin was measured by a traveling microscope. Based upon the results of this study it was demonstrated that there were significant differences amongst materials included in this study. Also this wear test not only reproduced the microstructure of worn oclusal surface, but also predicted wear rates which correlated somewhat well with clinical performances.

Analysis of Variance↗
PubMed1980

The central odontogenic fibroma: an attempt at clarification.

Three different but probably related central lesions of the jaws have been referred to previously as odontogenic fibromas. They are (1) hyperplastic dental follicles, (2) a fibrous neoplasm having a histologic appearance similar to that of a dental follicle, and (3) a more complicated lesion, illustrated in a WHO publication, consisting of fibrous connective tissue with varying amounts of odontogenic epithelium, dentin, and/or material resembling cementum. The terms simple odontogenic fibroma and odontogenic fibroma (WHO type) are proposed, respectively, for lesions 2 and 3 above. Some examples of lesion 3 may be confused histologically with the calcifying epithelial odontogenic tumor. More information is required on the biologic behavior of both 1 and 2. A central fibroma of the jaws should be considered a desmoplastic fibroma if it does not appear to have arisen from the odontogenic apparatus and is not a neurofibroma.

Dental Sac↗