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PubMed2006

A six-month clinical study of a self-etching and an etch-and-rinse adhesive applied as recommended and after doubling the number of adhesive coats.

PURPOSE: In an intra-individual comparison, a 6-month randomized, controlled prospective study evaluated the clinical performance of a self-etching and an etch-and-rinse adhesive in noncarious cervical lesions applied as recommended and after doubling the number of adhesive coats. MATERIALS AND METHODS: Twenty-nine patients with at least two pairs of similar sized noncarious cervical lesions participated. One hundred sixteen restorations were placed and divided into the following groups: OS2: phosphoric acid + One Step Plus applied accordingto manufacturer's recommendation (2 coats of adhesive); OS4: phosphoric acid + One Step Plus (4 coats of adhesive); TY2: Tyrian SPE + One Step Plus applied according to manufacturer's recommendation (2 coats of adhesive); TY4: Tyrian SPE + One Step Plus (4 coats of adhesive). The restorations were evaluated at baseline and after 6 months according to the modified USPHS criteria. Statistical analysis was performed with Friedman repeated measures ANOVA by rank and the Wilcoxon sign-ranked test for pairwise significance (alpha = 0.05). RESULTS: One hundred eight restorations were evaluated at 6 months. The retention rate of the group TY2 was statistically significantly lower than the other groups. Marginal discoloration occurred in all groups, being significantly worst in the group TY2. CONCLUSION: Tyrian SPE + One Step Plus applied according to manufacturer's recommendations did not meet the ADA provisional acceptance criteria for enamel-dentin bonded restorative materials. The use of four coats of the One Step Plus in the self-etching approach can improve its clinical performance.

Adhesives↗
PubMed1999

Dental implants in alveolar cleft patients: a retrospective study.

Since 1994, 15 cleft patients have received dental implants after treatment of the alveolar clefts by osteoplastic measures. Altogether 23 dental implants were undertaken. Twelve implants were inserted after tertiary osteoplasty, 7 with simultaneous repeat-osteoplasty, and another 4 implants following two-stage re-osteoplasty. In 11 patients with a total of 17 implants clinical and radiological follow-ups were performed. An individual crown was constructed on each of the implants. The radiological evaluation revealed that 70% of the implants were fully embedded in bone. All implants except one remained in situ and stable. Thus, the success rate was 96% retention. It is believed that a dental implant in the alveolar cleft may be lost because of its unfavourable location in terms of stability and function or because it was inserted too late. Scars resulting from previous surgery can also play a role in the failure of an implant. Therefore it is proposed that dental implants should not be inserted later than 6 to 8 weeks following osteoplasty of the cleft alveolus.

Adolescent↗
PubMed2002

[Techniques for immediate restoration of teeth following root canal therapy].

It is incumbent upon the dentist to restore the form and function of endodontically treated teeth. Different approaches and materials are described in the literature for restoring the missing tooth structure, either with a cast post and core or immediately with a chair-side post and core system. This article briefly reviews the available data regarding the microbiological, prosthetic, mechanical, and periodontal aspects while emphasizing the immediate approach using amalgam, composite and glass ionomer materials. The factors affecting retention of the post are presented to guide the clinician in selecting a suitable post and core system in preserving optimal root structure to prevent root fracture. Two clinical cases are presented in which tooth structure was restored using two techniques: in one, a provisional acrylic resin shell was used to house a dowel coronal-radicular amalgam core material, the other used a copper band for a composite post and core system. Both cases emphasize the ease of production and the short chair-time in the stages of crown fabrication.

Composite Resins↗
PubMedDate not supplied

All-ceramic crowns and preparation characteristics: a mathematic approach.

PURPOSE: The purpose of this investigation was to compare two mathematically calculated preparation parameters, ie, retentive capacity and finish line type, with a visual characterization based on a 3-D projection of the same prepared teeth on a PC screen. MATERIALS AND METHODS: Data from 400 teeth prepared for all-ceramic crowns recorded and manufactured by the Procera system, ie, 100 teeth each of types 11, 13, 14, and 16, were selected. Teeth were visually characterized for retentive capacity as good, acceptable, or insufficient, and type of finish line was characterized as deep chamfer, chamfer, or knife edge. For the mathematic calculations, data points located along vertical lines every 10 degrees around the tooth from finish line to occlusal/incisal midpoint were selected to calculate retentive area, defined as the part of the axial walls with an angle of less than 10 degrees to the preparation midline, and the area at the finish line with an angle of more than 45 degrees to the midline. RESULTS: Significant differences were found between the calculated size of surface areas for all types of prepared teeth visually characterized as having good retention and the two other categories (acceptable and insufficient). The difference between the latter two categories was not significant. Significant differences were also found between calculated surface areas for teeth visually characterized as having a deep chamfer and the two other finish line categories, ie, small chamfer and knife edge, but not between the latter two categories. CONCLUSION: The mathematic program allows a characterization of preparation parameters and may be further developed for use in prospective or retrospective studies of CAD/CAM restorations.

Algorithms↗
PubMed1996

The locking taper attachment for implant abutments: use and reliability.

The locking taper abutment attachment for implants is a one and one-half-degree tapered post that relies on friction rather than a screw for retention of the abutment to the implant. A retrospective analysis of 1,757 consecutively loaded implants was made to determine the reliability of the locking taper abutment. Five hundred and four implants restored over a 7-year period from one practice and a total of 1,253 implants restored over 4 years from 2 practices were reviewed. Nine abutment posts fractured for a failure rate of 0.05 percent. Thirty one (1.7 percent) of the abutments loosened but were reinserted without further problems. The technique for use of the locking taper implant abutment attachment is described.

Dental Abutments↗
PubMedDate not supplied

The influence of fatigue loading on the quality of the cement layer and retention strength of carbon fiber post-resin composite core restorations.

Clinical studies have shown that endodontically treated teeth restored with short posts or deficient ferrules show a high failure risk. This study. evaluated the influence of fatigue loading on the quality of the cement layer between prefabricated quartz coated carbon fiber posts with restricted length and the root canal wall in maxillary pre-molars. Two adhesive resin composite cements, chemical-cured Panavia 21 (Group 1) and dual-cured RelyX-ARC (Group 2), and one resin-modified glass-ionomer cement, chemical-cured RelyX (Group 3), delta were selected for this study. Post- and-core restorations were made on single-rooted human maxillary premolars from which the coronal sections were removed at the level of the proximal cemento-enamel junction (CEJ). Following endodontic treatment, a post-and-core restoration with 6-mm post length was prepared for each tooth. The posts were directly cemented into the root canal and, after applying an adhesive (Clearfil Photo Bond), they were built up with a core build-up composite (Clearfil Photo Core). For each group (n=8), half of the specimens were exposed to fatigue loading (10(6) load cycles) almost perpendicular to the axial axis (85 degrees), while the other half were used as the control. Three parallel, transverse root sections, 1.5-mm thick, were cut from each specimen at the apical, medial and coronal location. These sections were examined by Scanning Electron Microscopy (SEM) to evaluate the integrity of the cement layer, while the retention strength of the cemented post sections was determined with the push-out test. The multivariate results of MANOVA showed that the condition main effect (fatigue or control) was not significant (p=0.059); the two other main effects, type of cement and section location, were significant (p=0.001 and p=0.008). For both the push-out strength and SEM evaluation of the cement layer integrity, the results significantly improved from RelyX to RelyX-ARC to Panavia 21 and also from apical to coronal.

Bicuspid↗
PubMed2005

Clinical evaluation of a polyacid-modified resin composite in class V carious lesions: 3-year results.

This study evaluated the three-year clinical performance of Class V restorations made of a polyacid-modified resin composite, Dyract. Ninety-two Class V carious lesions in 28 patients were restored with Dyract. Restorations were clinically evaluated at baseline, first, second, and third year recall visits, according to the modified Ryge criteria by two experienced, calibrated examiners. Retention rate after three years in Class V carious restorations was 92.4%, with only seven failed restorations. Color change and marginal discoloration in restorations were found to be statistically significant (p = 0.013 and p < 0.001, respectively) at the end of third year, but none of the affected restorations required replacement. The results of this study revealed that at the end of three years, Dyract exhibited good clinical success rate but significant color change and marginal discoloration in Class V carious lesions.

Adolescent↗
PubMed2005

Trends in indirect dentistry: 3. Luting materials.

UNLABELLED: Luting materials play a central role in indirect dentistry. Active materials which bond to tooth and restoration may aid retention of restorations, while passive materials merely fill the gap between crown and tooth. The properties of currently available luting materials are discussed, with resin-modified glass ionomer and resin materials being found to exhibit optimum properties. However, resin luting materials have been technique sensitive to use, but the advent of self-adhesive resin luting materials has overcome most of the technique problems during placement of restorations. Resin materials are indicated for luting all-ceramic restorations. CLINICAL RELEVANCE: Correct choice of a luting material with optimum physical properties is central to success in indirect dentistry.

Dental Bonding↗
PubMed2005

The two-year clinical performance of esthetic restorative materials in noncarious cervical lesions.

BACKGROUND: Materials used in restoration of cervical lesions include resin-modified glass ionomer cements, polyacid-modified resin-based composites and resin-based composites. In this study, the authors evaluated the clinical performance of these materials over a two-year period. METHODS: Thirty patients were enrolled in this study. The authors placed in these patients 130 restorations, 24 of which were Vitremer (3M Dental Products, St. Paul, Minn.), 38 were F2000 Compomer (3M Dental Products), 46 were Dyract AP (Dentsply DeTrey, Konstanz, Germany) and 22 were Valux Plus (3M Dental Products). Enamel margins were not beveled, and no mechanical retention was placed. Two independent, calibrated examiners evaluated the restorations baseline and at one and two years after placement using modified U.S. Public Health Service criteria. RESULTS: Retention rates at the end of two years were 100 percent for Vitremer, 67 percent for F2000 Compomer, 68 percent for Dyract AP and 70 percent for Valux Plus. The retention rate of Vitremer was significantly higher than that of the others (P < .05). In other categories, however, Valux Plus had the most favorable performance (P < .05). No secondary caries was detected around any restoration. CONCLUSION: Vitremer, with its high retention rate, seems to be the most appropriate material for restoration of noncarious cervical lesions, though it does not have the esthetic properties of resin-based composites. All materials used in this study were in need of improvements. CLINICAL IMPLICATIONS: Resin-modified glass ionomer cement, polyacid-modified resin-based composite and resin-based composite behaved differently in the restoration of noncarious cervical lesions. Therefore, clinicians should take factors such as esthetic needs and localization into account in selecting materials for such restorations.

Adult↗
PubMed2002

Specific orofacial problems experienced by musicians.

BACKGROUND: Patients who play musical instruments (especially wind and stringed instruments) and vocalists are prone to particular types of orofacial problems. Some problems are caused by playing and some are the result of dental treatment. This paper proposes to give an insight into these problems and practical guidance to general practice dentists. METHOD: Information in this paper is gathered from studies published in dental, music and occupational health journals, and from discussions with career musicians and music teachers. RESULTS: Orthodontic problems, soft tissue trauma, focal dystonia, denture retention, herpes labialis, dry mouth and temporomandibular joint (TMJ) disorders were identified as orofacial problems of career musicians. Options available for prevention and palliative treatment as well as instrument selection are suggested to overcome these problems. CONCLUSIONS: Career musicians express reluctance to attend dentists who are not sensitive to their specific needs. General practitioner dentists who understand how the instruments impact on the orofacial structures and are aware of potential problems faced by musicians are able to offer preventive advice and supportive treatment to these patients, especially those in the early stages of their career.

Cumulative Trauma Disorders↗
PubMedDate not supplied

The effect of die-spacing on crown retention.

Ten extracted molar teeth were prepared to a standardised complete crown preparation. Five stone dies were constructed for each tooth and coated with zero, two, four, six, and eight layers of a paint-on die-spacer. Crowns were fabricated on each die and the force required for removal from each tooth was measured prior to cementation. The crown elevation and force required for removal were measured after luting with zinc phosphate cement. The force required to remove the crowns before cementation decreased with increasing layers of die-spacer. Following cementation, the mean crown elevation decreased from 547 micrometers (zero layers) to 38 micrometers (eight layers); while the mean removal force increased from 250 N (zero layers) to 375 N (eight layers).

Analysis of Variance↗
PubMed1999

Assessment of tooth preparation designs for posterior resin-bonded porcelain restorations.

Tooth preparation designs advocated for posterior resin-bonded porcelain restorations were evaluated for clinical application. This study examined the design of tooth preparations from stone dies for individual posterior resin-bonded porcelain onlays and complete porcelain crowns placed in a specialist practice, and compared features that provided retentive and porcelain fracture-resistance with those in the dental literature. Stone dies of tooth preparations for 57 onlay and 46 crown preparations were provided. Measurements were recorded for the tooth preparations with the aid of interocclusal silicone impressions. Proximal boxes, grooves and occlusal steps resulting from removal of amalgam restorations were common. These retentive features were more evident with onlays, and appeared larger on the distal than the mesial surfaces. Internal tooth preparation tapers or convergence angles were frequently greater than 20 degrees, leading to relatively-wide occlusal isthmus widths, especially for onlays. There were wide variations in occlusal surface reductions for the central fossae and supporting cusps. Tapers for tooth preparations were frequently more extensive, and occlusal surface reductions were often less than recommended. The implications of these differences for long-term clinical success should be resolved.

Adult↗
PubMed1998

Retention and marginal adaptation of a compomer placed in non-stress-bearing areas used with the total-etch technique: a 3-year retrospective study.

The aim of this clinical study was to evaluate class V and class III cavities restored with a polyacid-modified resin composite (compomer) restorative material in association with two different dentin-enamel bonding systems: Dyract-PSA (Primer Sealer Adhesive-DentSply, Germany) and Prime & Bond 2.0 (DentSply, Germany). The control group was a hybrid composite used with ProBond bonding system (DentSply, Germany). A total of 116 restorations (79 class V, 37 class III) were made and reevaluated after 1, 2 and 3 years in 55 patients in two private practices and in a university department. Class V nonretentive cavities were located at the CEJ level and class III at interproximal level close to CEJ. Each cavity was prepared using a water-cooled, high-speed handpiece with a fine diamond burr. A small bevel was prepared along enamel margin. Cavity dimensions were no more than 3.5 x 3.5 mm (using burr as reference point). Each restoration was finished immediately with fine diamond burrs and Sof-Lex disks (3 M, USA). The criteria that were evaluated by the USPHS method included: retention, color match, marginal integrity, marginal discoloration, and secondary caries. Results indicated that all compomer restorations were fully retained at 3 years, and that no secondary caries detected. Seven composite restorations were lost during the 3-year study. No statistical differences were observed between class III and class V or among other conditions (e.g., upper-lower arc, sex, age). This study demonstrates that compomers are suitable restorative materials for class III-V restorations. They may represent a clinical alternative to composites in class V and III restorations.

Adult↗
PubMedDate not supplied

Retention and shear bond strength of two post systems.

The purpose of this study was to compare the retention and shear strength of teeth restored with the Para Plus post (P) and the C post (C1 and C2) systems. Twenty-four P, C1, and C2 posts each were placed 7 mm into recently extracted and endodontically treated maxillary anterior roots and luted with Ketac-Cem and Bis-Core respectively. In addition, 13 samples of each post type had a Bis-Core composite core placed. The tensile retention strength of the post and the shear strength of the post and core restorations when the core was loaded buccolingually at 45 degrees to the roots' long axis were determined at a strain rate of 1.3 mm/min. The C2 posts required significantly more tensile force (P < 0.0001) to remove them than the P or C1 posts. The shear strength of the post/core restorations was not significantly different (P < 0.04). The C1 restorations had 12 root fractures, the C2 restorations had 11 root fractures, and the P samples had six root fractures. It was concluded that the lack of stiffness of the C posts adversely affected the success of these restorations.

Dental Bonding↗
PubMed2001

Posts and cores: when to use them.

The two overriding factors for successful post restoration are: 1. Retention, i.e., resistance to torsional forces. Published research is clear that threaded posts are the method of choice for the restoration of endodontically treated teeth in order to achieve optimal success. Prethreaded and self-threaded are the two systems from which to choose. The words active and passive should be applied to the method of producing threads, not the posts. The most gentle way to produce a thread is with a thread cutter. 2. Stress distribution of some cylindrical threaded posts has been shown to be far superior to nonthreaded cylindrical and nonthreaded tapered posts. With the acceptance of threaded, cylindrical prefabricated posts, new terminology has evolved, and the use and meaning of these words has been made more precise.

Dental Abutments↗
PubMed2000

Effect of die relief on the seating, fit and retention of cast gold crowns cemented on human teeth.

Die relief, by means of a paint-on die spacing material, is the most common method of achieving sufficient space between metal castings and tooth surfaces for cement to flow during seating. Several studies have determined the influence of cementing variables on crowns made for metal and plastic test dies. This study assessed the influence of die relief upon the seating and retention of cast gold crowns constructed for natural human teeth. Standard full crown preparations were made for 10 matched pairs of extracted human third molars, one each of which had been relieved with die spacer of approximately 40 microns thickness. Crowns were made by the indirect technique and were cemented with zinc phosphate cement in a static/dynamic jig. Seating behaviour and vertical discrepancies were measured electronically. Tensile bond strengths were determined in a universal testing machine. Results showed that die relief reduced vertical seating discrepancy associated with cementation by up to 79 microns. Differences between paired relieved and unrelieved samples were significant (p < 0.05). There were no statistically significant differences in tensile bond between paired relieved and unrelieved crowns.

Cementation↗
PubMed2006

Five-year clinical evaluation of Dyract in small Class I cavities.

PURPOSE: To evaluate the 5-year clinical performance of Dyract in small Class I cavities in non stress-bearing areas. METHODS: On 36 patients, 87 restorations needing small cavity preparations were performed. The lesions were diagnosed macroscopically with a probe. They involved shallow fissures, and had reached dentin but the lateral spread was limited and localized in dentin. Cavities were designed to be on non stress bearing areas. Cavities' average facio-lingual width were prepared to be 1/3 or less than the intercuspal width. At baseline, 1-, 2-, 3-, 4- and 5-year recalls, the restorations were evaluated according to the modified Ryge criteria by two calibrated, experienced examiners. RESULTS: None of the restorations was lost and retention rate was 100% at the end of 1 year. After 2 years, one restoration (1.2%) had to be replaced due to caries lesion adjacent to its margin and the rate of retention was 98.8%. At the 3-year recall, four restorations, at the 4-year, one restoration and at the 5-year, one restoration had caries lesions adjacent to their margins and the cumulative retention rates were 94.2%, 92.9% and 91.5% respectively. Significant differences were detected between all of the evaluation periods in regard to color match rate (P = 0.00001), with the exception of rate between the baseline and 1 year evaluations. In regard to the marginal discoloration rates, there were statistically significant differences (P = 0.00001) between all of the evaluation periods with the exception of rates between the baseline and 1-year, 3- and 4-year, and 4- and 5-year results. Except for the failed restoration, no other restoration was clinically unacceptable in regard to color match, wear or loss of anatomic form, marginal discoloration, caries, marginal adaptation and surface texture.

Adolescent↗
PubMed1994

The relationship between preparation convergence and retention of extracoronal retainers.

PURPOSE: Although traditional ideal convergence (the sum of taper of the opposite sides) for crown preparation has been arbitrarily set at 4 degrees to 10 degrees, some believe absolute parallelism yields the highest retention. This study examined the relationship between the degree of convergence of a machined metal die and the retention of its casting. MATERIALS AND METHODS: The method used was that of cementing cast metal crowns onto full crown preparations on brass dies with varying convergence angles, and then recording the force required to remove the crowns from the dies in a vertical direction using a Tate-Emery Testing Machine and Load Indicator. RESULTS: It was found that retention (i.e., the force needed to remove the cemented castings from the die in their common long axis) increases from 0 degree convergence to peak between 6 degrees to 12 degrees convergence. It also seems that a critical film thickness does exist for optimum retention, and that film thicknesses smaller than the critical thickness may be responsible for the phenomenon that we have observed and directly related to the convergence angle itself. CONCLUSIONS: There seems to be experimental data supporting the use of traditionally taught convergence. Our study found that convergence angles between 6 degrees and 12 degrees seem to be optimum for tooth crown preparation when one plans to use zinc phosphate cement. Convergence angles of less than 6 degrees may not be desirable even if they can be clinically achieved. The results of our study indicate that a relationship exists between the convergence angle and the critical cement thickness that is necessary to realize the maximum strength properties of zinc phosphate cement.

Analysis of Variance↗