Direct composite resin restorations of the anterior single tooth: clinical implications and practical applications

Modern technology has continued to improve composite resins to the point where they are commonly used in restorative dentistry. In spite of some drawbacks, such as polymerization shrinkage, incomplete conversion and cross-linking, and undesirable water sorption, the expected time of service of these restorations is extended continuously due to physical and chemical improvements. The improved handling and excellent optical properties of the latest generation of composite resins can provide the appearance of natural dentition. Sophisticated effects can be obtained through the use of direct intraoral applications of stratification techniques. This article discusses common indications for direct restoration of anterior teeth and their treatment in order to be biocompatible with the adjacent hard and soft tissues and to meet the requirements of form, function, and phonetics.     

Microleakage of dentin bonding systems used with spherical and admixed amalgams

PURPOSE: To evaluate the effectiveness of the dentin bonding systems (DBS) Tenure, Syntac, Amalgambond and All-Bond 2 using a resin-lined amalgam technique in preventing short-term microleakage in Class V cavity preparations restored with a spherical and an admixed alloy. MATERIALS AND METHODS: Class V cavity preparations were made on the mesial and distal surfaces of non-carious human mandibular molars with the occlusal margins in enamel and gingival margins in cementum. Prepared teeth were randomly assigned to 12 treatment groups (n = 10) consisting of each DBS, no liner and Copalite for both amalgam alloys. Samples were thermocycled, stained and sectioned to evaluate microleakage. RESULTS: The DBS-lined restorations had significantly less microleakage at both occlusal and gingival margins than the Copalite and unlined restorations. Among DBS, Syntac had significantly more microleakage with both alloys than either All-Bond 2 or Amalgambond. These results do not totally correlate to a previous study which used the same experimental design but included viscous liners in addition to the same DBS, indicating a potential difference between resin-lined versus resin-bonded amalgam techniques in preventing microleakage.     

"The view" and the canine connection: an atlas of mandibular anterior tooth esthetics

Restoring splinted mandibular incisors and canines with full crown restorations has always presented a challenge in creating an esthetic illusion of reality of normal individual teeth. This treatise is designed to present the rules for mandibular anterior esthetics that have been distilled from almost 4 decades of clinical practice of restoring dentitions that have been severely compromised by the deformities of disease or accident. The resultant formula systematically creates the desired results with a high degree of predictability.     

Microleakage of new dentin bonding systems using human and bovine teeth

The objective of this study was twofold: to evaluate the microleakage behavior of three dentin bonding systems and to determine if bovine teeth are comparable substrates to human teeth when studying the microleakage of various materials. The materials evaluated were Scotchbond Multi-Purpose Adhesive, Prisma Universal Bond 3, and All-Bond 2. All three bonding systems were used in combination with Prisma APH hybrid composite for comparison of microleakage behavior. Sixty class 5 preparations were cut at the cementoenamel junction for groups containing 30 human and 30 bovine teeth. A 1 mm 45 degree bevel was placed at the enamel margin. Teeth were grouped according to the dentin bonding system used and then restored according to the manufacturer's directions. After restoration, the teeth from each group were stored in distilled water at 37 degrees C for 3 days. The teeth were then thermocycled between 4 degrees C and 58 degrees C for 100 cycles and returned to distilled water at 37 degrees C for an additional 4 days. The teeth were then sealed with nail polish up to 1 mm from the margins of the restoration and placed in 45Ca isotope for 2 hours. The teeth were then sectioned and placed on x-ray film to produce autoradiographs. Microleakage was evaluated for the enamel and dentin margins separately using the following scale: 0 = no leakage, 1 = penetration of isotope to less than 1/2 the distance to the axial wall, 2 = penetration of isotope greater than 1/2 of the distance to the axial wall but short of the axial wall, and 3 = penetration of isotope to the axial wall or beyond. The materials were compared to each other using the Mann-Whitney U and Kruskal-Wallis tests. The gingival margins were compared to the incisal margins for all materials. No statistically significant differences in microleakage were revealed between the incisal and gingival location for human substrates, but there was statistically significant greater gingival microleakage for bovine substrates. All-Bond 2 leaked significantly more than Scotchbond Multi-Purpose for human substrates at the incisal margin. All-Bond 2 had significantly more microleakage than Prisma Universal Bond 3 at both dentin and enamel margins for the bovine substrate. There were no statistically significant differences in microleakage among the bonding systems for the human substrate. No statistically significant differences between the microleakage behavior of human and bovine substrates were found. These results support the use of bovine teeth for in vitro microleakage studies.     

Effect of 4-acryloxyethyltrimellitic acid in a self-etching primer on bonding to ground dentin

To develop a self-etching primer for ground dentin, 4-acryloxyethyltrimellitic acid (4-AET) was newly synthesized, and the effect of concentrations varying from 0 (control) to 56.5 wt% 4-AET in the water/ HEMA primer on bonding to the dentin was investigated. Bond strength to the dentin was significantly affected by the inclusion of 4-AET in the primer which also contained N,N-di(hydroxyethyl)-p-toluidine (DEPT) when compared with the control (0% 4-AET) (p < 0.01). The optimum 4-AET-concentration and the mean bond strength (SD) were found to be 6.5 wt%: 24.2 (3.6 MPa, 37.4 wt%: 25.3 (4.4) MPa, 47.2 wt%: 26.9 (11.6) MPa and 54.4 wt%: 29.7 (12.9) MPa. The role of DEPT in the 4-AET/HEMA primer was assessed, and the optimum DEPT-concentration was found to be 0.154 and 0.307 mol%. Regarding the hypothetical bonding mechanism to dentin, it was thought that the ionized 4-AET in water/HEMA would penetrate into dentin substrates, and DEPT as an accelerator in situ would facilitate photo-polymerization at the dentin-resin interface, and result in increased bond strength to ground dentin.     

Indirect composite restorations in the anterior region: a predictable technique for complex cases

The indirect composite inlay technique demonstrates excellent aesthetic results in the posterior regions, achieved by reproducing the shape, color, and contour of the natural tooth on a cast model rather than using the free-hand composite restorative modality. The utilization of the indirect technique can be adapted for the anterior regions as well, and it offers a valid treatment alternative that is predictable with optimal restorative results. The evaluation, planning, and accuracy of implementation of the various phases of this methodology allow a more precise achievement of the result; any potential error in the restoration can be corrected prior to final cementation. This technique increases the quality of composite restorations that have always been considered unpredictable and extensively dependent upon the skills of the operator. The learning objective of this article is to familiarize the reader with the clinical and laboratory phases of this indirect treatment modality of the anterior dentition.     

Hip fusion through an anterior approach with the use of a ventral plate

A new technique to achieve a reliable fusion of the hip joint through an anterior approach with use of a ventral low contact dynamic compression plate and a lateral 6.5 mm lag screw is presented in detail. The advantages of this technique are that the approach does not jeopardize the vascularity of the femoral head, that the fixation on the pelvic side uses the strong bone stock of the sciatic buttress, and that the hip abductor muscles and greater trochanter are preserved. The authors also present the indications and the results of their experience with 12 patients. The followup period averaged 24.8 months (range, 10-42 months). Ten patients (83%) achieved a solid fusion by radiologic and clinical criteria. Although a moderately symptomatic nonunion developed in 1 patient, another patient went on to a painful nonunion to whom another attempt for fusion has been recommended. According to the hip score of Merle d'Aubigné and Postel, the average figures for pain and ambulation increased from 3.2 points to 5.0 points and from 2.7 points to 4.5 points, respectively, after surgery. Six of the 12 patients regained the ability to work in their former jobs or in new occupations. Eight patients felt no or minor restrictions in doing their former sports activities. Patient satisfaction was high with a majority reporting minor discomfort mainly around the fused hip.     

Effect of application technique and dentin bonding agent interaction on shear bond strength

This study evaluated the interaction of five clinical application techniques and the shear bond strength of four DBAs (OptiBond FL, Clearfil SE Bond, PQ1 and Prime & Bond NT). A hybrid resin composite (Herculite XRV restorative resin) was attached to human dentin surfaces using five application techniques: Group A--adhesive spread with a 3M brush for 30 seconds, followed by compressed air 0.5 cm from the surface for one second to remove the excess adhesive. Group B--adhesive spread with a 3M brush for 30 seconds, followed by compressed air 0.5 cm from the surface for three seconds to remove the excess adhesive. Group C--adhesive spread with 3M brush for 30 seconds, excess adhesive removed with a clean brush, two strokes side by side, no compressed air. Group D--adhesive spread with a Micro-applicator brush for 30 seconds followed by compressed air 0.5 cm from the surface for one second to remove the excess adhesive. Group E--adhesive spread with a Micro-applicator brush for 30 seconds, the excess adhesive removed with a clean brush, two strokes side by side and no compressed air. The specimens were stored in distilled water at 37 degrees C for 24 hours, followed by thermocycling between 5 degrees C and 55 degrees C for 1,000 cycles. The shear bond strengths were determined on a universal testing machine operating with a crosshead speed of 5 mm/minute. The fracture sites were examined by 20x stereo microscope to determine the type of failure that occurred during the debonding procedure. Bond strength data were compared with analysis of variance at a significance level of p<0.05. Post hoc comparisons of means were performed with t-tests with p-values adjusted for multiple comparisons. This in vitro study concluded that there was an interaction between the application technique and bonding agent tested. All DBAs utilized the one-second compressed air technique, which yielded the highest bond strengths.     

Optimizing multiple individual anterior implant restorations with a new generation implant-abutment system; IMZTwinPlus: a case report and treatment rationale

A 53-year-old male with a history of initial oral facial trauma causing the loss of three maxillary incisors, multiple failures of tooth-borne fixed prosthetic reconstructions, and a resultant condition of structural failure of abutment cuspids and lateral incisor was to be retreated. The case contained numerous anatomic and dimensional constraints. The patient's desire to achieve a long-term, dependable prosthetic reconstruction prompted professional consideration of incorporating implants to lend structural support in the edentulous area. An extensive review of current implant-abutment options and their single-tooth implant replacement design and treatment rationales was conducted. The IMZ Generation III (IMZTwinPlus) implant system, a nonhex system, was chosen for treatment of the case of report to optimize mechanics, biomechanics, and esthetics for multiple individual-tooth implant replacement.     

Steering without representation with the use of active fixation

This paper demonstrates the use of active fixation on both fixed and moving fixation points to guide a robot vehicle by means of a steering rule which, at large distances, sets the steering angle directly proportional to the deviation of gaze direction from translation direction. Steering a motor vehicle around a winding but otherwise uncluttered road has been observed by Land and Lee to involve repeated periods of visual fixation upon the tangent point of the inside of each bend. We suggest that proportional rule devised for steering in the robotic example appears applicable to the observed human performance data, providing an alternative explanation to the quadratic rule proposed by Land and Lee.     

Effects of aminobenzoic acid derivatives with 4-AET/HEMA in self-etching primer on bonding to ground dentin

The effect of the inclusion of aminobenzoic acid derivatives (ABAD) in a self-etching primer comprising 4-acryloxyethyltrimellitic acid (4-AET), HEMA and water on shear bond strength to ground dentin was investigated. The mean bond strengths to dentin were significantly increased by the inclusion of 0.307 mol% ABAD in the 4-AET/HEMA primer, when compared with the control (0 wt% ABAD) (p < 0.01). A particularly high value (38.0 MPa) of shear bond strength was obtained in the use of the primer containing p-nitroanthranilic acid (p-NAA). It seemed to assume that the effect of p-NAA could be caused by the strong electron-withdrawing group of -NO2. From SEM observation, it was found that bonding resin appeared to adhere strongly to the ground dentin without formation of any resin-tags in the dentinal tubules. It was thought that the ABAD with 4-AET/HEMA could perform facilitating photo-polymerization at the bonding interface, and resulted in increased bond strength to ground dentin, and that the bond strength could be affected by the electronegativities of substitutional groups of ABAD.