Influence of CAD/CAM fabrication on denture surface properties.

Three main properties are responsible for the microbial attractiveness of denture surfaces: roughness, hydrophilicity and free surface energy. This study investigated whether CAD/CAM-fabricated dentures are more favourable for these surface properties than conventionally fabricated dentures. The mucosal surface roughness of 54 standardised study dentures was measured using contact profilometry. The surface hydrophilicity and free surface energy of 70 standardised denture resin specimens were determined by contact angle measurements. Both experimental settings compared AvaDent (AD), Baltic Denture System (BDS), Vita VIONIC (VV), Whole You Nexteeth (WN) and Wieland Digital Dentures (WDD) surfaces with conventionally manufactured denture surfaces (control group). These data were analysed using ANOVA together with Tukey's test or the Games-Howell post hoc test. All CAD/CAM dentures had lower mean surface roughness values than conventional dentures. For AD, VV, WN and WDD, the differences were statistically significant. Vita VIONIC (P < .001), coated WN (P < .001), AD (P = .023) and BDS specimens (P = .027) were significantly more hydrophilic than the control group. All measured surface energies were of similar magnitude (mean values between 31.82 and 33.68 mJ/m2 ), and only coated WN specimens had a significantly increased mean value (66.62 mJ/m2 , P < .001). Although most CAD/CAM dentures have smoother and more hydrophilic surfaces than conventional dentures, there is no difference in their free surface energy, except for coated dentures.

Shortcomings of prosthodontic rehabilitation of patients living in long-term care facilities.

Removable dentures are a non-invasive, cost-effective prosthodontic solution for the reduced dentition. Their intended purpose is the rehabilitation of harmonious oral function and aesthetics on a long-term basis. The prevalence of removable dentures among patients of advanced age is high and the quality of the dentures is often poor. The aim of this study was to find the most important shortcomings of removable dentures and address the main targets for improving the quality of prosthodontic rehabilitation. The records from dental check-ups in Austrian residential homes were analysed retrospectively. Dental anamnesis questionnaires and data from the clinical examinations of 105 denture wearers were analysed. The functional condition and retention of 192 dentures had been assessed, as well as the impact of the dentures on the intra-oral tissues. Insufficient denture retention was very common, particularly in the lower jaw (56·0%). Problems with the masticatory function were reported by 26.7% of the denture wearers, 11·4% were dissatisfied with the denture aesthetics, and 4·8% had difficulties with phonetics. Traumatic ulcers were found in 18·1%. Cracks, broken pieces (6·3%) or missing denture teeth (2·1%) were rare. It may be assumed that the findings of the present study also apply to a great percentage of community-dwelling seniors. The most important issues in prosthodontic rehabilitation with removable dentures are denture retention and masticatory function. Regular dental check-ups, denture adjustment and, when necessary, relining can maintain the primary denture quality and prevent damages of the oral tissues caused by ill-fitting dentures.

Porcelain laminate veneers. A retrospective evaluation after 1 to 10 years of service: Part II--Clinical results.

PURPOSE: The objective of this study was to evaluate the clinical quality of 191 porcelain laminate veneers and to explore the gingival response in a long-term survey. MATERIALS AND METHODS: The clinical examination was made by two calibrated examiners following modified California Dental Association/Ryge criteria. In addition, margin index, papillary bleeding index, sulcus probing depth, and increase in gingival recession were recorded. Two age groups were formed to evaluate the influence of wearing time upon the clinical results. The results were statistically evaluated using the Kaplan-Meier survival estimation method, Chi-squared test, and Kruskal-Wallis test. RESULTS: A failure rate of 4% was found. Six of the total of seven failures were seen when veneers were partially bonded to dentin. Marginal integrity was acceptable in 99% and was rated as excellent in 63%. Superficial marginal discoloration was present in 17%. Slight marginal recession was detected in 31%, and bleeding on probing was found in 25%. CONCLUSION: Porcelain laminate veneers offer a predictable and successful treatment modality that preserves a maximum of sound tooth structure. An increased risk of failure is present only when veneers are partially bonded to dentin. The estimated survival probability over a period of 10 years is 91%.

Bonding porcelain laminate veneer provisional restorations: An experimental study.

STATEMENT OF PROBLEM: Minimal tooth preparation is required for porcelain laminate veneers, but an interim restoration is anticipated by patients to protect their teeth against thermal insult, chemical irritation, and to provide esthetics. Cement remaining after the removal of the provisional restoration can impair the etching quality of the tooth surface and the fit and final bonding of the porcelain laminate veneer. PURPOSE: This in vitro study inspected the tooth surface for remaining debris from cement after removal of a provisional restoration. MATERIAL AND METHODS: Seventy-two extracted natural anterior teeth were prepared for porcelain laminate veneers. For half of the teeth, the smear layer was removed before luting provisional restorations. Veneer provisional restorations were fabricated and luted to teeth with 3 bonding methods: temporary eugenol-free cement, spot etching combined with dual-curing luting cement, and polyurethane adhesive combined with dual-curing luting cement. After removal of provisional restorations 1 week later, the tooth surface was examined for residual luting material with an SEM. RESULTS: Traces of cement debris were found on provisionally prepared teeth for all 3 material methods. CONCLUSION: The use of polyurethane adhesive combined with the dual-curing cement revealed significantly less teeth with debris than the other methods. This difference was less distinct when the smear layer was removed.

Porcelain laminate veneers. A retrospective evaluation after 1 to 10 years of service: Part I--Clinical procedure.

PURPOSE: Currently available clinical studies on porcelain laminate veneers seem to support their use as a standard treatment method in modern restorative dentistry. The purpose of this study, which comprises 3 parts, was to evaluate the clinical applicability and the survival probability of porcelain laminate veneers for an observation period of up to 10 years. This first part of the study describes the step-by-step clinical procedure. MATERIALS AND METHODS: The reasons for provision of porcelain laminate veneers were mainly for the treatment of worn anterior teeth, surface enamel defects, intrinsic discolorations, and hypoplasia. As the treatment time for try-in, cementation, and finishing of veneers differs significantly from that needed for conventional restorations, the total time required for veneer treatment was evaluated. RESULTS: A total of 205 porcelain laminate veneers, 117 in the maxilla and 88 in the mandible, was placed in 72 patients (43 females and 29 males). Mean cementation time was 38.7 minutes, which increased significantly to 43.9 minutes if single discolored teeth were being restored. Clinical experience and a familiarity with the strict step-by-step procedure followed throughout the study reduced the mean treatment time from 40.8 minutes during the first 5 years to 36.7 minutes in the following years. CONCLUSION: The porcelain laminate veneer concept provides excellent esthetic and conservative restorations, but it should be stated that the cementation and finishing procedure is highly time consuming.

A new approach in restorative treatment of external root resorption. A case report.

This case report describes the treatment of an external root resorption with extensive loss of tooth structure and bone at the labial surface of an upper left central incisor. The area of bone loss and root resorption was surgically exposed and an impression was taken using curing silicone. An individual ceramic insert was fabricated, allowing endodontic retreatment through an artificial root canal. The insert was incorporated using a dentin bonding system and a dual curing luting composite. Following endodontic retreatment and internal bleaching, a ceramic veneer was bonded to the tooth to obtain good esthetics and to improve stability. Twenty months after surgical treatment no further root resorption could be detected radiographically. A shallow residual pocket but no bleeding on probing was found.

[The biomechanics of space closure and its dependence on the periodontal attachment]. / Die Biomechanik des Lückenschlusses und ihre Abhängigkeit vom parodontalen Attachment.

The biomechanics of space closure in adult patients with loss of periodontal attachment is described. In order to achieve an even force distribution in the periodontium, force was reduced and the moment to force relationship was increased. beta-TMA-T Loops of 0.016 inch x 0.022 inch and 0.017 inch x 0.025 inch cross sections were investigated. With an automatic testing device force and moment values were determined.

[Shear strength measurements for the clinical evaluation of bonded ceramic systems]. / Scherfestigkeitsmessung zur klinischen Bewertung von Keramik-verbundsystemen.

The shear bond strength of dental ceramic (Dicor, Optec) and luting composite (Dicor, Optec, Dual-cement) bonded to dentin and to etched enamel was evaluated. The mean bond strength was 23.8 N/mm2 to enamel and 0.60 N/mm2 to dentin. Using the Optec dentinal bonding agents increased these values to 2.00 N/mm2.

[Material testing for the use of titanium in bonded prosthodontic restorations]. / Werkstoffkundliche Untersuchung zur Anwendung von Titan in der Adhäsivprothetik.

The effects of chemically etching cast pure titanium to achieve a microretentive surface morphology were studied by SEM. Etching failed to produce an effective improvement of the retentive structures compared to air brushing with Al2 O3 of 50 microns grain size. The bond strength values of the Silicoater-treated retentive surfaces of titanium and Wiron 88 (bonding agent Comspan) determined by shear tests were considerably higher than those of the air-brushed or chemically etched surfaces (bonding agents Comspan, ABC-Zement, Superbond). The clinical use of the Silicoater procedure in bonded restorations seems to provide a suitable retentive mechanism for titanium frameworks.

[Transverse dimensional stability of whole jaw models of different materials]. / Transversales Dimensionsverhalten von Gazkiefermodellen aus verschiedenen Modellmaterialien.

Whole jaw models of 6 different materials were examined for their transverse dimensional stability. Under standardized conditions impressions were made of a mandibular phantom with 4 stylized crown stumps using the double mix-spray technique with additively cross-linking silicon. Of these, test models were prepared and measured using the original model as reference. The high-strength dental stones Die Keen and Fuji Rock showed the highest dimensional stability. On account of their shrinkage during polymerization, the epoxy resins Blue Star E and Metapox as well as Blue Star P, a polyurethane, were found to have smaller transverse stump interspaces. Data for electroplated silver models were between those for dental stones and plastic materials.

[Long-lasting treatment technic in the periodontally reduced dentition]. / Die festsitzende Behandlungstechnik im parodontal reduzierten Gebiss.

A precondition for satisfactory (long-lasting) prosthetic results is a good occlusion. This can sometimes only be achieved with the aid of orthodontics. This article concludes that orthodontics can be carried out in patients with reduced periodontal support provided thorough periodontal treatment is carried out initially and treatment goals and biomechanics are carefully considered.

[The use of modern ceramics for inlays and onlays]. / Die Anwendung moderner keramischer Materialien in der Inlay-Onlay-Technik.

If ceramic inlays and onlays are considered in restorative work, some operations which, more than in other areas of dental engineering, decide upon the success or failure should be given special attention. During the preparation of ceramic inlays care should be taken to produce well rounded rather than rectangular edges approximally. In the case of onlays there should ideally be a smooth circular step rounded axially with a sharp-edged near-rectangular interface with the non-ground tooth. Ceramic inlays and onlays are best inserted with the adhesive technique, which provides for an improved strength of the ceramic material, an adequate marginal adaptation and a satisfactory cosmetic appearance. As long-term results are not yet available, the use of ceramic inlays and onlays is still experimental.

Distance alterations of dies in sagittal direction in dependence of the die material.

The distance alterations between the first premolar and second molar in the sagittal direction were measured on complete arch models in two planes. Two dental stones, three resins, and silver-plating were used to make reproductions of a master cast under standardized conditions. Special emphasis was directed to the distinction between the right half of the model with teeth between the dies and the left side edentulous between the dies. The stones Die Keen and Fuji Rock showed the least distortion, identical bilaterally. The epoxy resins Blue Star E and Metapox exhibited a significant distinction between the right and the left sides. In addition to the pronounced distance reduction caused by polymerization shrinkage, a divergence between the dies and the model base on the side with teeth was measured. This phenomenon was also observed with polyurethane Blue Star P resin, but was less substantial. Silver-plating recorded a slightly greater reduction in distance between the dies than Fuji Rock. However, no significant differences were found between both sides.

[Free mucosal grafting--clinical experiences]. / Klinische Erfahrungen mit dem freien Schleimhauttransplantat.

Free mucosal grafting is a simple, safe and predictable procedure. It is indicated in the treatment of progressive recessions in patients with reduced attached gingiva, in recurrent traumatic marginal lesions inspite of correct tooth brushing, in refractory dental neck hypersensitivity and for cosmetic reasons in patients with recessions. In these situations advancement grafting is done as a secondary procedure. To prevent the potential occurrence of recessions free mucosal grafting may also be indicated prophylactically before orthodontic or prosthetic management. The management concept in patients with recessions as well as the indications of the procedure, the technique used at our department and aspects of planning surgery are discussed.

[Surface structures and substance loss during the etching of ceramic materials]. / Oberflächenstruktur und Substanzverlust beim Atzen keramischer Materialien.

The progressive development of all-ceramic systems used in prosthetic dentistry gives material-specific aspects a new significance. It was the purpose of this study to examine the surface morphology of various ceramics (Mirage, Dicor, Optec, Vitadur N, Ceramco II) etched with various solutions (Super-Etch, Stripit, hydrofluoric acid 40%, Dicor retention gel) and etching times (1, 2, 3, and 4 min), using a SEM. With the exception of Dicor, the etched surface of ceramics showed similar structures within each material group, regardless of the etching time and the etching solution used. Dicor showed a different pattern depending on the etching time. An additional measurement of the surface roughness revealed an advisable etching time of 1 min with an average loss of ceramic material of 1.6 microns for those ceramics treated with the etching solutions Super-Etch, Stripit and Dicor retention gel. Hydrofluoric acid 40% caused a significant loss of substance and should not be used. A qualitative evaluation of the surface structure of composite cements (Chameleon, Dicor, Optec and Dual cement) in etched ceramics and in etched enamel showed completely filled microretentions.