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PubMedDate not supplied

Fracture resistance of premolars with bonded class II amalgams.

This study evaluated the fracture resistance of maxillary premolars with MOD cavity preparation and simulated periodontal ligament. The teeth were restored with silver amalgam (G1), Scotchbond Multi-Purpose Plus and silver amalgam (G2) and Panavia F and silver amalgam (G3). After restorations were made, the specimens were stored at 37 degrees C for 24 hours at 100% humidity and submitted to the compression test in the Universal Testing Machine (Instron). The statistical analysis of the results (ANOVA and Tukey Test) revealed that the fracture resistance of group 2 (G2=105.720 kgF) was superior to those of groups 1 (G1=72.433 kgF) and 3 (G3=80.505 kgF) that did not differ between them.

Analysis of Variance↗
PubMedDate not supplied

The use of shimstock to assess occlusal contacts: a laboratory study.

PURPOSE: This laboratory study investigated the influence of varying occlusal forces, occlusal contacts, or small gaps (0 to 8 microns) on the force required to pull 8-micron shimstock from between a tooth and a restorative material specimen. MATERIALS AND METHODS: An apparatus was developed and calibrated to (1) produce and measure very small gaps (0 to 20 microns) and apply variable occlusal forces between specimens, and (2) pull shimstock consistently from between the specimens and measure the removal force. An unworn maxillary molar cusp and polished amalgam were used as the opposing specimens. Combinations of occlusal forces from 0 to 400 g and gaps of 0 (contact), 2, 4, 6, and 8 microns were tested. RESULTS: Shimstock removal forces increased linearly with increasing occlusal force with 0-, 2-, 4-, and 6-micron gap settings. With 0-, 2-, and 4-micron gaps, there was no significant difference in removal force. With a 6-micron gap, the forces rose but at a lower gradient. With the 8-micron gap, the mean force was low (less than 12 g). CONCLUSION: The shimstock removal force increased with occlusal force and was highest with the smaller gaps. Using 8-micron shimstock, 0-, 2-, and 4-micron gaps cannot be differentiated, a gap of up to 6 microns may still be assessed as a holding contact because the shimstock is still gripped, and even an 8-micron gap may be recorded as a light contact since there is still friction on removal.

Analysis of Variance↗
PubMedDate not supplied

Marginal and internal adaptation of stratified compomer-composite Class II restorations.

Different approaches have been proposed to improve the adaptation of Class II restorations, including applying low-elasticity modulus base liners. This in vitro fatigue test (or study) evaluated the influence of the compomer base-lining configuration on restoration adaptation. Direct Class II MOD box-shaped composite restorations with or without base and lining (n=3x8) were placed on intact human third molars with proximal margins 1 mm above or under the CEJ. The compomer (Dyract) was applied as a 1 mm-thick lining or as a base, closing proximo-gingival margins. Marginal adaptation was assessed before and after each phase of mechanical loading (250,000 cycles at 50N, 250,000 cycles at 75N and 500,000 cycles at 100N); internal adaptation was evaluated after test completion. Gold-sputtered resin replicas were observed in the SEM and restoration quality evaluated in percentages of continuity (C) at the margins and within the internal interface after sample section. Mechanical loading did not influence adaptation to enamel, while it adversely affected restoration adaptation to dentin for the full composite and compomer-base restorations (C varied, respectively, from 95.2 to 75.3% and from 98.0 to 10.6%). The internal adaptation quality showed the same general trend, however, with reduced scores of continuity. In this experimental condition, application of a low elasticity modulus layer under the restorative material proved advantageous but the compomer should not contact the gingival margins.

Bisphenol A-Glycidyl Methacrylate↗
PubMedDate not supplied

The influence of a packable resin composite, conventional resin composite and amalgam on molar cuspal stiffness.

Packable resin composites may offer improved properties and clinical performance over conventional resin composites or dental amalgam. This in vitro study examined the cuspal stiffness of molars restored with a packable resin composite, a conventional posterior microfilled resin composite and amalgam. Forty-eight intact caries-free human third molars were distributed into four treatment groups (n=12) so that the mean cross-sectional areas of all groups were equal. Standardized MOD cavity preparations were made and specimens restored using one of four restorative materials: (1) a spherical particle amalgam (Tytin); (2) Tytin amalgam with a dentin adhesive liner (OptiBond Solo); (3) a conventional microfilled posterior resin composite (Heliomolar); (4) a packable posterior resin composite (Prodigy Posterior). Cuspal stiffness was measured using a Bionix 200 biomaterials testing machine (MTS). Specimens were loaded vertically to 300 N at a crosshead speed of 1.0 mm/minute. Stiffness was measured at 10 intervals: (1) prior to cavity preparation (intact); (2) following cavity preparation, but before restoration; (3) seven days after restoration; then (4) 1, 2, 3, 4, 5, 6 and 12 months after restoration. All specimens were stored at 37 degrees C in deionized water throughout the study and thermocycled (5 degrees/55 degrees C; 2000 cycles) monthly for 12 months. Repeated Measures ANOVA revealed significant differences among treatment groups over time (p<0.0001). Cavity preparation reduced cuspal stiffness by more than 60%. At 12 months, the cuspal stiffness of restored teeth was, on average, 58% that of intact specimens. Neither the packable nor the conventional resin composite increased cuspal stiffness over that of amalgam.

Acrylic Resins↗
PubMed2002

Ingot selection for aesthetic restorations using contemporary pressed ceramics.

Accurate communication among the patient, clinician, and laboratory technician is critical to the development of a functional, aesthetic restoration. The use of pressed ceramic restorations has provided a durable, consistent alternative for full-coverage crowns, veneers, onlays, and short-span fixed partial dentures. This article discusses the importance of proper ingot selection in the fabrication of aesthetic restorations and in the realization of patients' expectations for smile design. Ceramic ingots are available in a variety of colors and opacities that provide the clinician and laboratory technician with the latitude to select an ingot that will ultimately ensure patient satisfaction.

Aluminum Silicates↗
PubMed2002

Beyond cosmetics--the esthetic rehabilitative patient.

The evolution of the esthetic movement has been sustained over time because it touches a base psychological need for most people to feel they are attractive, youthful, and a vital part of society. Through well-organized team diagnosis and treatment planning, patients can benefit from a solid diagnostic and prerestorative foundation that can more predictably produce consistent optimal treatment results. As the chief diagnostician and treatment supervisor, the restorative dentist must continue to advance his or her knowledge and training to provide the other team members with a concise treatment vision for the patient. With a newly developed synergy among the disciplines of dentistry for team treatment and tremendous advancement in dental markets and equipment, it is possible to create natural-looking, esthetic rehabilitative treatments.

Adult↗
PubMed2000

Cosmetic dentistry for patients who can't afford it.

As I noted earlier, all things being equal, patients prefer tooth-colored restorations. This technique has removed virtually all the barriers to treatment and makes things a lot more equal. There's the cost factor (Dramatically reduced!) There's the fear-of-needle factor (Gone!) There's the time factor (Minimized!). In fact, prepping and placing these occlusal veneers is so fast I can now do 8 to 10 amalgam rehabs in one appointment. Doing so many in a short time is extremely profitable, even at the reduced fee. This technique certainly does not qualify as "great dentistry," but it brings "desire-motivated" cosmetic dentistry to an entirely new universe and those patients are appreciative. They're even referring their friends! In my practice, veneering amalgam has brought cosmetic dentistry to many patients who would never agree to have their restorations replaced with traditional composite resin. And it has brought me several additional thousand dollars in collections each month. So this is a classic "win-win" situation. Patients are getting cosmetic restorations they didn't think they could afford, and I'm making a great profit doing it.

Acid Etching, Dental↗
PubMed2002

[Long-term results of front teeth restoration using light-curing composite materials].

200 patients (500 restorations of front teeth) were examined. All the restorations were made of light-curing composite materials (microfills, hybrids, compomers, and combination of microfills and hybrids) from 5 do 9 years ago. Clinical and esthetical parameters were evaluated. We had to replace 96 restorations of 500 (19.2%), only 50 (10%) restorations were marked as "excellent". Direct veneers made of microfilled composite materials showed the best results (30%--"excellent" restorations). The restorations of devital teeth and V-class restorations of compomer material show the worse result (20% restorations replaced).

Compomers↗
PubMed2002

The influence of cervical lesion on the stress state and strength of tooth with occlusal restoration: a numerical model study.

This paper is concerned with bio-engineering problems in dentistry. The analysis of stress in a lower premolar with a deep non-carious cervical lesion and restored occlusal Class I cavity under occlusal load of 100 N was shown. Finite element method was used for the analysis of a two-dimensional model of a human tooth. In order to facilitate the evaluation of the loads, four cross-sections in characteristical points of the model were made. The model was generated and the calculations were done on IBM Pentium III personal computer. The principal and equivalent stresses were calculated and used in qualitative and quantative evaluation of tooth tissue and tooth restoration strength. The results are shown in figures and charts. The analysis of the cross-sections distant to the cervical area has proved that the presence or absence of cervical lesion has no significant influence on the values and stress distribution. Only in the region of sharp-shaped notch in the bottom of defect (4-4) high stresses in the tooth tissues occur. The values of stress did not exceed the compressive and tensile strength in any case under investigation. The study has shown that the presence of cervical angular lesion does not affect the mechanical strength of a tooth with a properly restored occlusal cavity. Clinically, the situation is safe from the biomechanical point of view.

Biomechanical Phenomena↗
PubMed2001

[Research on the high strength all ceramic crown by the combination of CAD/CAM and glass infiltrated alumina blocks].

OBJECTIVE: To search for a method that fabricates the high strength all ceramic crown by the combination of CAD/CAM and glass-infiltrated alumina. METHODS: Alumina coping was milled by the Cerec II CAD/CAM and glass was infiltrated into alumina by the capillary effect. Vita alpha ceramic was used to veneer the surface of substructure for all ceramic crown. RESULTS: This technology need not duplicate die and sinter alumina substructure for 10 h, compared with the conventional In-ceram technology. The time of glass infiltration has been decreased from 4 h to 40 minutes by the high capillary effects of prefabricated alumina blocks. CONCLUSION: This is a new method for all ceramic crown by using Cerec II CAD/CAM to mill a simple ceramic block so as to fabricate prosthetics in clinic.

Aluminum Oxide↗
PubMed2002

Proximal contact formation with different restorative materials and techniques.

PURPOSE: To determine, whether different tooth colored materials and application techniques influence the proximal contact strengths (PCS) in vitro. MATERIALS AND METHODS: Standardized MO-cavities for direct restorations were prepared into 360 artificial lower first molars. Eight groups were formed (n = 45) and restored with amalgam (1), low (2, 3), medium (4, 5) and high (6, 7) viscosity hybrid composites and compared to the original contact strengths of the unprepared teeth (8). The restored teeth were mounted into a socket simulating physiological tooth mobility. PCS were quantified by measuring the forces necessary for passing the proximal contact with floss under standardized conditions using a universal testing machine. RESULTS: PCS ranged from 1.32 +/- 0.56 N for the low viscosity composite to 9.90 +/- 1.98 N for the Amalgam restoration. Medium (5.65 +/- 1.08 N) and high viscosity hybrid composites (5.90 +/- 1.45 N) inserted in a multi-layer technique showed no statistically significant differences to the original PCS of the unprepared teeth (5.76 +/- 0.53 N).

Analysis of Variance↗