Abrasivity of denture cleaning pastes in vitro and in situ.
Explore the source record for details and available documents.
Acrylic Resins↗
SEARCH · Search PubMed
Results for “TOOTH, ARTIFICIAL”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The effect of three commercially available saliva substitutes on enamel in vitro.
Explore the source record for details and available documents.
Carboxymethylcellulose Sodium↗
Complete denture construction in general dental practice: an update of the 1970 survey.
A survey was carried out on materials and techniques used for complete denture construction in general dental practice, by means of a postal questionnaire sent to a random sample of 1000 dentists whose names were taken from the BDA membership. There was a 71.5% response. The results obtained are compared with a similar survey undertaken in 1970. The majority of practitioners still provided dentures totally or mainly within the NHS. Whilst the demand for complete dentures was reported as having remained stable, there has been considerable reduction in the numbers of dental technicians employed by general dental practitioners. Alginate remains the impression material of choice and the majority of impressions were sent to a commercial laboratory for pouring. Although still the most popular, the use of the plane-line hinge articulator has reduced and there has also been a continued reduction in the use of porcelain teeth. The importance of a cross-infection policy is highlighted. There were conflicting opinions expressed on the role of implants in general dental practice. Many respondents took the opportunity to comment on the status of dental prosthetics under the NHS and most criticised the fee structure.
Acquired Immunodeficiency Syndrome↗
New formulation for 'Luborant' saliva substitute.
Explore the source record for details and available documents.
Humans↗
Immediate addition to acrylic partial dentures.
The conventional method of adding teeth to an existing prosthesis has the disadvantage that patients must be without their dentures while the teeth are added. Whilst a new immediate denture avoids this, it means that the patient will have to grow accustomed to the shape of a new polished surface. The method described in this paper eliminates these problems by making an immediate addition to the existing partial denture. Additionally, the technique has been found to be beneficial to those patients who are unable to tolerate conventional impression taking procedures.
Acrylic Resins↗
How well are complete dentures copied?
OBJECTIVE: To assess how accurately the same set of complete dentures could be copied by 12 different laboratories. DESIGN: A prospective study. SETTINGS: Completed by commercial laboratories used by GDPs in England (1996). Results were analysed and controlled by a university department. SUBJECTS (MATERIALS) AND METHODS: The master set was constructed to include a midline diastema and a bilateral posterior crossbite. Twelve sets of silicone moulds of the master denture were prepared. GDPs selected commercial laboratories of their choice to receive the work. MAIN OUTCOME MEASURES: All stages of the work were compared with the master dentures by returning them to a specially adapted articulator. Analysis was completed using preset criteria. RESULTS: Only five of the returned copies were considered to have both good quality acrylic resin work and clear details of the teeth in wax. Only four cases reproduced the diastema. After processing, the occlusal vertical dimension had been increased in eight of the cases and the bilateral crossbite had been eliminated in all cases. CONCLUSIONS: None of the final copy dentures were considered an accurate copy of the master dentures. There is considerable scope for further training of dental technicians in this important technique.
Acrylic Resins↗
Real-time monitoring of stain formation and removal on calcium hydroxyapatite surfaces using quartz crystal sensor technology.
Stain formation, stain inhibition and stain removal may be monitored in real-time using a novel method employing a quartz crystal resonance sensor (QCR), based upon quartz crystal microbalance (QCM) technologies. Crystalline hydroxyapatite (HA) surfaces were prepared on phosphate-terminated, polymer-modified gold surfaces of quartz crystal transducers. The resulting sensors were placed in a specially constructed flow cell, and the interaction of adsorbates from the tea stain solution monitored as a function of time. The ability of sodium tripolyphosphate (STP) to remove extrinsic stain and also to inhibit its formation was examined. The adsorption of material from the staining solution passed over the sensor was clearly observable, and once bound, the crystal based real-time data suggest that tea adsorbates were not removed in the absence of an active under conditions of continuous flow. STP was shown to rapidly remove existing stain, and exhibited a clear inhibitory action on stain formation irrespective of whether the HA had been previously exposed to tea chromogens. The continuous data generated by the QCR technique were in good agreement with the results obtained using a discontinuous spectrophotometric method. The presently described quartz crystal model for extrinsic dental stain should provide a valuable tool to aid understanding of the interactions of staining agents with a crystalline HA surface as a model tooth surface, and to evaluate the efficacy and mode of action of STP and putative stain removal agents.
Coloring Agents↗
Biostereometric quantification of clinical denture tooth wear.
In this study the wear of mandibular acrylic resin teeth opposed by porcelain maxillary teeth arranged in a lingualized occlusal scheme over a period of 3 years was measured. Six edentulous subjects received complete dentures as above and with three baseline markers of amalgam. At yearly intervals casts were made of the mandibular occlusal surfaces, including markers, and plotted by stereophotogrammetry. Volumetric loss of material was quantifiable. Ranges of 0.62-3.33 mm3/mm2 on the left side and 0.71-1.64 mm3/mm2 on the right were recorded. Friedman two-way ANOVA test indicated significant wear on teeth 35, 36, 45 and 46 but not on 34 and 44. A one-sided chewer displayed greater wear on the contralateral side, a finding difficult to explain.
Acrylic Resins↗
Studies of changes in occlusion after the insertion of complete dentures (part II).
The aim of this clinical experimental study was to investigate whether, and what, changes in occlusion occur between 3 weeks and 1 year after insertion of complete dentures. Twenty-six edentulous patients, who already had their jaw relation registered for part I of this study some 357 days before, were re-examined. The same special non-arcon measuring articulator was used for determination of any positional differences between the presently recorded central condylar position with inter-occlusal gap and the equilibrated intercuspal position, from approximately 1 year previous. Differences were recorded electronically in the condylar area in three dimensions. The position of the condylar balls of the measuring articulator in maximum intercuspation had shifted, since the previous recording, by about 0.62 +/- 0.04 mm (0.04-1.76 mm) in the sagittal and 0.89 +/- 0.72 mm (0.01-3.06 mm) in the vertical direction. Whereas the differences measured in maximum intercuspation scattered in the sagittal plane uniformly around the centric condylar position, in the vertical plane they were shifted cranially about an average of 0.77 +/- 0.85 mm (1.06 mm caudally to 3.06 mm cranially). The results indicate that in half of the patients from the present sample the occlusion did not remain stable, which is assumed to be mainly caused by resorption of alveolar bone and abrasion of the acrylic teeth. Therefore, at each check-up visit not only the health of the denture-bearing tissues and the fit of the dentures, but also the mandibular posture and the occlusion should be examined carefully.
Acrylic Resins↗
Effect of denture thickness on tooth movement during processing of complete dentures.
In this investigation the effect of denture thickness on tooth movement during processing of complete dentures was studied. A maxillary cast from a patient was duplicated to obtain 10 identical casts. Base plates were constructed on five casts using 1.25 mm thick wax. Base plates were constructed on the other five casts using 2.5 mm thick wax. Teeth were placed on the ridge of each cast and a TMS pin was placed vertically, upright, in each tooth. The dentures were invested, cured, decasted, finished and polished. Each denture was radiographed immediately before processing, after deflasking, on removal from the cast and after finishing and polishing using a standard technique. The radiographs were digitized using an Eikonix image digitizer. The results showed that there were significant variations in tooth movement between thick and thin denture bases. Also an increase in the molar-to-molar distance was found in both the thin and thick dentures but the magnitude of tooth movement was more in thick dentures.
Dental Casting Technique↗
Intercondylar width as a guide to setting up complete denture teeth.
A clinical study was designed to investigate the relationship between intercondylar width (ICW) and inter-dental widths of the upper and lower canines and first molars to aid in denture teeth positioning. The study was divided into two parts so that the results of the first part could be verified in the second part. In the first part, 27 adult subjects were selected according to the exclusion criteria of the study. A kinematic hinge axis locator was used to locate the true point of condylar rotation. The distance between these points was considered to be the ICW. A strong correlation was found between ICW and interdental measurements, with ICW and upper first molars being the strongest (r=0.612, P= 0.004). A set of indices developed from the results was recommended for the positioning of complete denture teeth. In the second part of the study, inter-dental measurements were estimated using the indices obtained in the first part. The estimated inter-dental widths showed no significant differences compared with the real widths (P= 0.109, P=0.849, P=0.353, P=0.41). Based on the results of this study, ICW measurements can be used for setting up canines and first molars in complete dentures.
Adolescent↗
An in vitro wear study of posterior denture tooth materials on human enamel.
This in vitro study evaluated the wear effects of five posterior denture tooth materials on human enamel. The tooth specimen was cusp shaped and enamel specimen was formed as a 10 C 10 C 5 mm plate. All material-enamel combinations were tested using a machine designed to produce sliding contact 20 C 104 times at 60 cycles min-1 and a 4-mm sliding distance per stroke in the bucco-lingual direction under a load of 1 kg. Wear analysis was measured as the total height loss of each combination. In addition, the surface roughness (Ra) of each worn specimen was also evaluated. The least total height loss occurred with poly (methyl methacrylate) (PMMA) enamel pair, and the greatest did with porcelain (Po)-enamel pair. The lowest compound Ra value was measured in high-strength resin (HR)-enamel pair, and the highest in Po-enamel pair. These findings suggest that the best combination is PMMA-enamel, and the poorest combination is Po-enamel.
Acrylates↗
Fracture strength of four different types of anterior 3-unit bridges after thermo-mechanical fatigue in the dual-axis chewing simulator.
The purpose of this study was to evaluate the fracture strength of four different types of anterior 3-unit bridges after thermo-mechanical fatigue in a dual-axis chewing simulator. Sixty-four human maxillary incisors were prepared and 32 bridges fabricated. The four groups of eight bridges each were - (GC): AGC(R) galvano-ceramic bridges (CA): Celay(R) In-Ceram(R) Alumina bridges (E2): heat-pressed lithium disilicate glass-ceramic bridges and (CM) ceramo-metal (control). Fracture loads were recorded after a dual-axis chewing simulator and in a universal testing machine. The survival rate after 5 years for the CM and the GC groups was 100%, for the E2 group 75% and for the CA group 37.5% (Kaplan-Mayer analysis). The mean fracture strengths (N) were 681.52 +/- 151.90 (CM); 397.71 +/- 59.02 (GC); 292.92 +/- 46.45 (E2) and 239.95 +/- 33.39 (CA), respectively. The log-rank test showed a significant difference between the CA and the GC or the CA and the CM groups. No significant differences between the E2 and the CA or the E2 and the GC groups were found. The study indicates that heat-pressed lithium disilicate glass-ceramic and AGC(R) galvano-ceramic bridges are alternatives to ceramo-metal 3-unit anterior bridges.
Aluminum Oxide↗
The dynamic behaviour of a lower complete denture during unilateral loads: analysis using the finite element method.
The purpose of this study was to analyse the correlation between the location and/or direction of unilateral load and the dynamic behaviour of a mandibular complete denture using the three-dimensional finite element method (FEM). The FE model consisted of the body of mandible, alveolar mucosa, and a complete denture, and it could simulate the condition of contact between the surface of the mucosa and mucosal surface of a denture. Load vectors, which simulated premature contacts, were calculated on the supposition that a premature contact on an occlusal facet causes a vertical load on it. Load-A, a load vertical to the anterior occlusal facet, caused the least displacement of the denture and less concentrated stress distribution. Load-P, a load vertical to the posterior occlusal facet, was characterized by the stress distributed in the lingual area of the pre-molar lesion on the contra-lateral side of the load. Load-B, a load vertical to the balancing occlusal facet, caused the largest displacement of the denture. The relationship between loads and stress distribution was agreed approximately with the observations previously reported, and lead to some suggestions about occlusion for complete dentures.
Alveolar Process↗
Handling characteristics of a palladium-free gallium-based alloy compared with a high copper dental amalgam in a simulated clinical trial.
The aim of the current study was to compare the handling characteristics of a palladium-free gallium-based alloys (Galloy) with those of a high-copper amalgam (Permite C). The study had a particular interest in the evaluation of the direct placement delivery system used with both alloys. Ten dentists participated in the current study. Each placed two amalgam and two gallium-based alloy restorations in conventional class II cavities prepared in acrylic typodont teeth. None of the participating dentists had used the direct placement delivery system or had any previous experience with gallium-based alloy and no practice was allowed beforehand. The restorations were evaluated according to the following criteria: ease of loading the cavity (delivery system), ease of condensation, capacity to produce and sustain contact area, ease of carving, resistance to damage during removal of the matrix band, overall quality of the restoration and the available working time. Each criterion was given a score on a scale of 1-5 (1: very poor, 2: poor, 3: fair, 4: good, 5: very good). The results showed no statistically significant difference in the evaluated criteria between the two alloys (P > 0.05) except for criterion number 2 (ease of condensation, P=0.0005).
Acrylic Resins↗
In vitro wear assessment of titanium alloy teeth.
PURPOSE: Wear of commercially pure (CP) titanium prosthetic teeth has frequently been observed. The greatest wear has been found when the same grades of CP titanium are used for both maxillary and mandibular teeth. This study examined the wear behavior of teeth made with cast titanium alloy and compared these results with those for CP titanium and gold alloy teeth. MATERIALS AND METHODS: All tooth specimens were cast with grade 3 alpha titanium, 3 metastable beta alloys [Ti-15Mo-2.8Nb-0.2Si (Timetal 21 SRx), Ti-13Nb-13Zr, and Ti-15V-3Cr-3Sn-3Al], and 2 alpha+beta alloys (Ti-6Al-7Nb and Ti-6Al-4V). As a control, Type IV gold alloy was also cast conventionally. All teeth (both maxillary and mandibular) were secured in an in vitro 2-body wear testing apparatus that simulated chewing function (60 strokes/min; grinding distance, 2 mm under flowing water). Wear resistance was assessed as volume loss (mm(3)) at 5 kgf (grinding force) after 50,000 strokes. The results (n = 5) were analyzed using analysis of variance or Fisher's exact test (alpha = 0.05). RESULTS: Of the titanium teeth, the wear of 2 of the metastable beta alloys (Timetal 21 SRx and Ti-15V-3Cr-3Sn-3Al) was found to be significantly (p <0.05) higher than that of CP titanium and the 2 alpha+beta alloys. The Type IV gold alloy exhibited better wear resistance than all of the titanium teeth tested. No correlation was found between wear loss and hardness among all the metals tested. CONCLUSIONS: Among the titanium teeth examined, the alpha+beta alloys exhibited significantly less wear than the other types of titanium. The dental casting gold alloy tested exhibited the best wear resistance among all of the metals tested.
Alloys↗
Laboratory fabrication of gold occlusal surfaces for removable and implant-supported prostheses.
This article describes a technique for fabricating prosthetic teeth with gold occlusal surfaces for removable or implant-supported prostheses. Following a successful wax try-in appointment, the denture teeth used in the prosthesis are invested in a denture flask. After deflasking, the gingival 2/3 of the denture teeth are trimmed away. The remaining occlusal portions of the teeth are invested in a gypsum-bonded investment and cast in a type III gold alloy. After polishing, the castings are repositioned back into their respective sites in the flask. An acrylic resin of an appropriate shade is mixed and packed in the flask. Once the acrylic resin is processed to the metal occlusal surfaces, the individual teeth are removed from the flask and polished. Then the finished teeth are reinserted in the wax trial denture, the occlusion is refined, the final wax-up is completed, and the prosthesis is processed.
Acrylic Resins↗