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Congenital absence of teeth is a heritably phenomenon probably most often passed to each generation by an autosomal dominant pattern with incomplete penetrance and variable expressivity. Correlation of hypodontia with systemic disease leads to the hypothesis that this frequent dental anomaly may in some cases be a microform of systemic ectodermal dysplasia.
OBJECTIVE: To study the tarnish induced by Aay4 on titanium and Ti-75 alloys. METHODS: Pure titanium and Ti-75 alloys were machined into size of 10 mm x 10 mm x 1 mm in tablets(30 of pure titanium; 60 of Ti-75 alloys). Thirty specimens sampled randomly from Ti-75 alloy together with 30 specimens of titanium were subjected to chemical passivation treatment. 30 specimens of the pure titanium, depassivation Ti-75 alloy and passivation Ti-75 alloy were randomly divided into three groups (blank control group, media control group and inoculated media group) respectively, every group contains 10 specimens. Under the anaerobic conditions, the surfaces of the modified GAM media were inoculated with Aay4. The labeled specimens surfaces were then aseptically placed on top of the media surface for 10 weeks with one generation time per week. The specimens were removed after 10 weeks of incubation, immersed in 0.05% glutaradehyde solution to eliminate Aay4, rinsed with distilled water. After 2 weeks, the specimens were removed and observed visually or examined by MINOLTA CR-100 color apparatus. RESULTS: Visual evaluation: Aay4 caused significant tarnish on specimens exposed to inoculated media, all the specimens surface changed into yellow color. Color apparatus evaluation: this result showed that comparing with the blank control, media control has no influence on all the specimens L*a*b* values (P > 0.05). Aay4 caused significant tarnish on specimens exposed to inoculated media, the result showed that there was significant difference between media control group and blank control group with inoculated media group on all the specimens L*a*b* values (P < 0.05). CONCLUSION: Aay4 caused significant tarnish on pure titanium, depassivation Ti-75 alloys and passivation Ti-75 alloys by naked eyes and color apparatus, according CIE1976L*a*b* color system reading, the color of titanium and Ti-75 alloys changed from the yellow-green ranges to red-yellow ranges.
AIM: To evaluate an apex locator in determining the working length of root canals and detecting micro-communications with the pulp chamber. METHODS: The apparatus was tested on 21 patients, aged 18 - 70, who received endodontic treatment of 34 teeth with 45 root canals. The apparatus was used in compliance with the instructions of the manufacturer. The precision of the instrument was determined by a radiograph of the tooth with a file inserted in it at a depth equal to the length determined with the Apex locator. The obtained results were divided into three groups: canals determined as longer; canals in which the outline of the instrument was close to the roentgenologic apex; and canals determined as shorter. CONCLUSION: The average deviation from the roentgenologic apex was 1.17 mm, which is, in fact, the area of the physiological apex opening - the ideal limits for treatment and obturation. The apparatus can be successfully used to make differential diagnosis is useful of deep caries with pulpitis chronica ulcerosa. It is ergonomic and easy to use.
This paper reports the development of a newly modified, noncontact spectrophotometer for clinical use. The instrument is capable of accurately measuring the color within small areas (1 x 2 mm) of a tooth. This spectrophotometer used a 45 degree/0 degree geometry, a 150W halogen lamp, and fiberoptics to focus the light, together with a lens having a focal point distance of 85 mm. A movable platform was added to the apparatus to automatically scan and measure the color of specific areas. Short-term repeatability indicated the color difference delta E to be approximately 0.15.
The complexity of the oral environment, and ethical problems associated with studies of oral diseases in humans inevitably directed the attention to development of laboratory models, that simulate the human oral microcosm. These developments and in particular the in vitro 'artificial mouth' systems have progressed from simple and basic apparatus devised by Magitot and Miller at the end of 19th century to the currently available, highly sophisticated, computer-controlled, multi-station artificial mouth systems. These advances have metamorphosed from the early studies devised primarily to investigate factors affecting the carious process to the present designs that evaluate growth, pathogenicity, metabolism and mineralization of dental plaque under highly controlled conditions. The modern 'artificial mouth systems' can evaluate microbial interactions in simulated dental plaque and similar biofilms and monitor their physical, chemical, biological and molecular features to a very high degree of accuracy. We review and trace here the historical aspects and developments leading to the currently available artificial mouth systems and discuss their contribution to the study of oral flora, especially related to many variants of dental caries.
To investigate the hypothesis of a functional coupling between the stomatognathic motor apparatus and the muscles of other body districts, as well as between occlusal conditions and neuromuscular performance, two groups of men (age range 20-26 years), with either normal occlusion (14 men) or malocclusion (15 men), sustained with their dominant arm a dumbbell weighing 80% of their maximum while maintaining different jaw positions: mouth open, without dental contact; mouth close, with light dental contact; maximum voluntary clench; maximum voluntary clench on two cotton rolls positioned on the posterior mandibular teeth; maximum voluntary clench on one cotton roll positioned on the right/left-side posterior mandibular teeth. Surface electromyography (EMG) of the biceps brachii muscle was performed, and the endurance time, mean root mean square (rms) potential, and mean median power frequency were computed. The mean potential and median power frequency were also computed for 2-s windows, and values as a function of time were interpolated by a linear regression analysis. Data were compared between groups and trials by using a factorial analysis of variance. The malocclusion group subjects could perform the exercise for a longer time span than the normal occlusion individuals (P < 0.005). During this endurance time their biceps brachii muscles contracted with different patterns: on average, in the malocclusion group they had a larger EMG amplitude (P < 0.005), and a shift of the power spectrum toward lower frequencies (P < 0.005). The factor 'jaw position' was significant only for the endurance time (P < 0.005). In both groups, the longest endurance time was found in the 'clench' trial, while the shortest in the 'right-side bite' trial. In conclusion, a morphologically altered occlusion does not always worsen the muscular performance of other body districts, and the use of occlusal supports (cotton rolls) is not always beneficial.
Fifty-four homozygous beta-thalassemic patients (26 men and 28 women) aged 7 to 24 years, who had been treated with high transfusion regimen (Hb levels = 9-10 g/dl) and chelation therapy (desferrioxamine, 35-50 mg/kg), underwent clinical and radiographic investigations. This study was aimed at assessing the clinical and radiographic changes in the stomatognathic system (teeth, mandible and maxilla, occlusion relationship and dental bases). All patients underwent orthopantomography and teleradiography of the skull, in the lateral view. Twenty thalassemic patients (13 men and 7 women) of the same age but treated with low transfusion regimes (Hb levels = 5-6 g/dl) were examined as a control group. Our results indicate that: 1) in the control group, osteopenia is the specific lesion of anemia, in both the alveolar process and the mandible, following marrow expansion. Consequently, diastema of incisors and several types of malocclusion follow--i.e., overjet, anterior open-bite and crossbite, nearly all of them associated with II dental and skeletal patterns of Angle's classification. 2) In adequately transfused patients, no lesions are observed in 55% of cases, in both the teeth and the facial skeleton. This means that current treatment methods can prevent bone abnormalities, especially if transfusions begin at birth. Nevertheless, osteopenia of the mandible (31.4%) and dental and/or skeletal malocclusions (40.7%) remain in many cases, because of persistent marrow expansion, which usually follows incorrect treatment. 3) General dental diseases--e.g., caries, paradentosis, gingivitis, etc.--affect both populations with the same incidence.
BACKGROUND: Dental caries is a bacterially mediated disease characterised by demineralisation of the tooth surface, which may lead to cavitation, discomfort, pain and eventual tooth loss. Ozone is toxic to certain bacteria in vitro and it has been suggested that delivering ozone into a carious lesion might reduce the number of cariogenic bacteria. This possibly could arrest the progress of the lesion and may, in the presence of fluoride, perhaps allow remineralisation to occur. This may in turn delay or prevent the need for traditional dental conservation by 'drilling and filling'. OBJECTIVES: To assess whether ozone is effective in arresting or reversing the progression of dental caries. SEARCH STRATEGY: We searched the Cochrane Oral Health Group's Trials Register (to 7 November 2003); Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2003); MEDLINE and PREMEDLINE (OVID, 1966 to November 2003); EMBASE (OVID, 1980 to November 2003); CINAHL (OVID, 1982 to November 2003); AMED (OVID, 1985 to November 2003). Quintessence was handsearched through 2002 and KaVo were contacted as manufacturers of the HealOzone apparatus for any additional published or unpublished trials. SELECTION CRITERIA: Inclusion was assessed independently by at least two reviewers. Trials were only included if they met the following criteria: randomisation in a controlled trial; single surface in vivo carious lesion accessible to ozone application; clear allocation concealment; ozone application to the lesions in the intervention group; no such application of ozone in the control group; outcomes measured after at least 6 months. DATA COLLECTION AND ANALYSIS: Reviewers independently extracted information in duplicate. A paucity of comparable data did not allow meta-analytic pooling of the included studies. MAIN RESULTS: Three trials were included, with a combined total of 432 randomised lesions (137 participants). Forty-two conference papers, abstracts and posters were excluded (from an unknown number of studies). The risk of bias in all studies appeared high. The analyses of all three studies were conducted at the level of the lesion, which is not independent of the person, for this reason pooling of data was not appropriate or attempted. Individual studies showed inconsistent effects of ozone on caries, across different measures of caries progression or regression. Few secondary outcomes were reported, but one trial reported an absence of adverse events. REVIEWERS' CONCLUSIONS: Given the high risk of bias in the available studies and lack of consistency between different outcome measures, there is no reliable evidence that application of ozone gas to the surface of decayed teeth stops or reverses the decay process. There is a fundamental need for more evidence of appropriate rigour and quality before the use of ozone can be accepted into mainstream primary dental care or can be considered a viable alternative to current methods for the management and treatment of dental caries.
The purpose of the present case report is to clinically and histologically evaluate the healing of one advanced intrabony defect following treatment with an enamel matrix protein derivative (EMD) combined with a bovine-derived xenograft (BDX) and guided tissue regeneration (GTR). One patient with generalized chronic periodontitis and one advanced intrabony defect was treated with EMD + BDX + GTR. Notches were placed in the root at the level of the calculus and alveolar crest to aid histologic identification of new periodontal tissues. Postoperative healing was uneventful. At the 7-month histologic examination, healing in the intrabony component of the defect was characterized by formation of new connective tissue attachment (new cellular cementum with inserting collagen fibers) and new bone in the intrabony component. The BDX particles were surrounded by bone-like tissue. No direct contact between the graft particles and root surface (cementum or dentin) was observed. Healing in the suprabony defect component occurred through epithelial downgrowth that stopped at the level of the coronal notch. The BDX particles were entirely encapsulated in dense connective tissue, without any signs of bone formation. The present case report shows formation of new attachment apparatus consisting of new bone, cementum, and periodontal ligament in the intrabony component of one human defect treated with EMD + BDX + GTR.
The role of periodontics in dentistry is changing subtly from primarily resective procedures to regenerative techniques that are becoming increasingly more predictable. The periodontal focus is shifting to regeneration of the attachment apparatus, guided bone regeneration and more desirable implant placement. However, certain techniques and materials may not be as predictable as others and therein lies the predicament for the practicing clinician.
This report is on the care of a temporary denture with gaps in the front area of the upper jaw with fixed and removable artificial dentures (children's prosthesis), covering aspects of gnathoorthopaedic necessity (support zone, tongue habit), aesthetic and speech functions.
The iatrogenic transmission of hepatitis B virus by inadequately sterilized acupuncture needles recently has been reported. Because some licensed chiropractors use acupuncture as a therapeutic modality, we have evaluated sterilization methods for these needles, which would be adaptable for use in a chiropractic office. Dry heat, boiling water, pressurized steam, sodium hypochlorite, and 70% alcohol were compared with a glass bead dry heat sterilizer originally developed for dental instruments. Presterilized acupuncture needles were contaminated with Bacillus stearothermophilus, Escherichia coli or Staphylococcus epidermidis and sterilized for intervals ranging from 5 sec to 30 min. The needles were then cultured to determine the efficacy of the sterilization regimen. Seventy percent alcohol was ineffective as a sterilization method. In terms of both time and convenience, the glass bead apparatus was the most efficient of the remaining methods tested. B. stearothermophilus-contaminated acupuncture needles were sterilized within 10 sec of exposure to preheated glass beads. Less than 10 sec exposure killed E. coli and S. epidermidis. A significant advantage of the glass bead sterilizer over the other methods was the absence of physical damage to the needles.
Branchial cysts and fistulae in the lateral part of the neck are believed to arise from the same remnant of the branchial arches. The two lesions, however, are distinct and separate. Clinical findings of the fistulae could be related to the branchial apparatus. In contradistinction the age of manifestation, the localisation, the history, th symptoms and the histological features of the lateral cervical cysts disagree in regard to the branchial origin. That is why various congenital hypotheses are discussed and rejected, partly because the existence of stratified squamous cells in cervical lymph nodes present recent suggestions. The lateral lesions and dental cysts, especially radicular cysts, are compared. Both kinds of cystic structures are often associated with an initial infection.
A method has been described to measure the retention of luting cements to ground dentin in vitro. Using a specially designed apparatus, a circular disc of cement was produced on a ground dentin surface of equal diameter. In a universal testing machine a tensile stress was applied to the cement disc pulling it parallel with the dentin surface at right angles to the diamond grooves until separation. The effect of two different cleansing procedures on the retentive ability of two dental cements was investigated. The cleansing procedures were: rubbing ground dentin with Tubulicid or polishing with wet pumice. The cements studied were a polycarboxylate cement (Durelon) and a zinc phosphate cement (De Trey's Zink Zement Improved). The retentive ability of the polycarboxylate cement showed values from six to seventeen times those of the zinc phosphate cement. The retentive ability of zinc phosphate cement was only slightly affected by the two cleansing procedures, while for polycarboxylate cement it was somewhat reduced following rubbing with Tubulicid and greatly improved after polishing with pumice and water.
After using cast titanium prostheses in clinical dental practice, severe wear of titanium teeth has been observed. This in vitro study evaluated the wear behavior of teeth made with several cast titanium alloys containing copper (CP Ti+3.0 wt% Cu; CP Ti+5.0 wt% Cu; Ti-6Al-4V +1.0 wt% Cu; Ti-6Al-4V+4.0 wt% Cu) and compared the results with those for commercially pure (CP) titanium, Ti-6Al-4V, and gold alloy. Wear testing was performed by repeatedly grinding upper and lower teeth under flowing water in an experimental testing apparatus. Wear resistance was assessed as volume loss (mm(3)) at 5kgf (grinding force) after 50,000 strokes. Greater wear was found for the six types of titanium than for the gold alloy. The wear resistance of the experimental CP Ti+Cu and Ti-6Al-4V+Cu alloys was better than that of CP titanium and Ti-6Al-4V, respectively. Although the gold alloy had the best wear property, the 4% Cu in Ti-6Al-4V alloy exhibited the best results among the titanium metals. Alloying with copper, which introduced the alpha Ti/Ti(2)Cu eutectoid, seemed to improve the wear resistance.
The purpose of this study was to compare the machining efficiency of a flexible stainless steel K-type hand file recently introduced by Brasseler USA ("F-Style files"), with that of a well-studied Endodontic instrument ("Flex-o-files," Maillefer Dentsply), that has been on the market for more than 20 years. The comparison of machining efficiencies of these two brands of files was conducted on both dentin and plexiglas substrates, using an apparatus that allowed a constant force to be applied from each file being tested. The results indicated that the Brasseler instruments had poorer machining efficiency than those of the Maillefer files.
Microleakage studies were undertaken for Class II composite resin restorations that had been lined with glass-ionomer cement using the 'sandwich' technique. Thirty freshly extracted permanent molars and premolars were mounted in polymethylmethacrylate blocks. Class II cavities were prepared using carbide burs No. 245 in a water cooled dental handpiece, (cavity box 5 x 3 x 2 mm). Specimens were divided into three groups of 10 each. Group A was restored with hybrid composite resin only, Group B with hybrid composite using a light-cured glass-ionomer liner applied to dentin only, and Group C with hybrid composite using light-cured glass-ionomer liner carried out to the cavosurface margin, (beyond the DEJ). All the specimens were thermocycled between 5 degrees C and 55 degrees C for 250 cycles for 3 hours, followed by placement in 0.5% aqueous basic fuchsin dye for 24 hours at 37 degrees C. Specimens were sectioned mesio-distally through the restorations using an Isomet apparatus. The extent of dye penetration was scored under a stereomicroscope with reference to the DEJ, (0 = no penetration, 1 = penetration to the enamel, 2 = penetration beyond the DEJ). Statistical analysis of the data showed significant differences among the means of the groups at p < 0.001. The results of this study indicate that the application of a light-cured glass-ionomer up to the cavosurface margin inhibits the microleakage of Class II restorations in vitro.
STATEMENT OF PROBLEM: Many studies on the strengthening effects of grinding and polishing, as well as heat treatment on ceramics, are not well standardized or use commercially available industrial polishing systems. The reported effectiveness of these strengthening mechanisms on ceramics may not be applicable to clinical dentistry. PURPOSE: The purpose of this study was to evaluate the effects of controlled polishing on the flexural strength of dental ceramics by using a custom-made machine that applied standardized loads and speeds that coincided with the mean loads and speeds used by experienced prosthodontists. MATERIAL AND METHODS: A total of 140 aluminous dental ceramic bar-shaped specimens (Vitadur Alpha Enamel) measuring 1.5 x 2.0 x 25 mm were fabricated and divided into 12 groups (for most groups, n=10). Specimens were untreated, polished with different polishing systems, polished at different speeds, ground and autoglazed, polished and autoglazed, autoglazed and polished, polished with loose (paste) and bonded abrasives, or overglazed. Simulated clinical polishing was performed on the ceramic specimens by using a customized polishing apparatus that allowed independent control over the relevant polishing parameters (abrasive hardness, applied load, linear speed, rotational velocity, and wheel stiffness). Flexural strength (MPa) was measured with a 4-point bending test, and subjective surface roughness was assessed with scanning electron microscopy. Autoglazing was performed at various stages of the polishing sequence to determine the effects of polishing on surface stresses. Mean values, standard deviations, independent-sample t tests, 1-way and 2-way analyses of variance, Dunnett t tests and Kruskal-Wallis tests were applied to the data (alpha=.05). RESULTS: Under a clinical load of 0.6 N for a coarse polishing wheel, 1.0 N for a medium polishing wheel, and 1.3 N for a fine polishing wheel, a linear speed of 499 mm/min, and a rotational velocity of 10,000 rpm, the use of clinical polishing instruments did not affect the flexural strength of the aluminous ceramics studied (P=.274). At higher rotational velocity (20,000 rpm), specimens polished with the diamond polishing system produced statistically weaker specimens compared with those that had been polished at 10,000 rpm (P=.019). Autoglazing treatment of the diamond-polished specimens did not reverse the strength degradation (P=.125). Conversely, diamond polishing of the autoglazed specimens resulted in significant flexural strength reduction (P=.029). Fine-diamond-bonded abrasive significantly reduced flexural strength (P=.025). CONCLUSIONS: Simulated clinical polishing at 10,000 rpm did not appear to substantially strengthen or weaken the ceramic specimens. Polishing at 20,000 rpm reduced flexural strength of the ceramic bars.