Quintessence International, 03/1994

This study was performed to examine the 9-year success of the composite resin/sealant restoration, which uses sealing for prevention of fissure caries rather than cavity extension for prevention. Three hundred thirty-two Class I restorations were placed in the occlusal surfaces of 240 permanent molar teeth in 114 children aged 6 to 14. Cavity preparations were made in occlusal surfaces, and caries was removed with no attempt to create any additional retention or remove undermined enamel. Exposed dentin was covered with Dycal and the cavity was restored with Radipaque Adaptic, which was then covered with Delton fissure sealant. Incipient lesions confined to the enamel were restored only with Delton. After 9 years, 79 restorations in 28 subjects were examined for sealant retention, marginal staining, and the presence of dental caries. Forty-three restorations (54%) had completely retained sealants, 20 (25%) had sustained partial loss, and 16 (20%) of the restorations had lost all sealant. Dental caries occurred in 19 (25%) of the restorations that had sealant loss. An additional 16 teeth had proximal caries unrelated to the occlusal restoration. These findings demonstrated that the composite resin/sealant (preventive resin) restoration produced excellent long-term results.

This case history describes and illustrates the excellent esth etic results now clinically possible when fixed appliance orthodontic therapy is combined with porcelain veneers to treat severe tetracycline staining and crowding. Because the patient also presented with a bimaxillary protursion and a displaced maxillary midline, the treatment options also illustrate the dilemma between ideal, but prlonged, treatment options and quicker, but compromised, alternatives. The excellent final result accepted the initial protrusion but corrected the midline. A long-span bonded multistrand wire functioned as semipermanent retention.

Crown lengthening has been advocated as a treatment modality to restore teeth with a clinical crown reduced subsequent to different kinds of trauma. Multirooted teeth, however, present certain anatomic features, such as the furcation area and corresponding interradicular bone, the retromolar area, and the external oblique ridge, that may limit the possibility for soft tissue and bone reduction and minimize the effectiveness of crown-lengthening procedures. This article describes surgical modifications to overcome the anatomic difficulties that multirooted teeth present when crown lengthening is required. Furthermore, root resection is discussed as an alternative to conventional surgery when the latter is not possible.

Judicious retention of roots can alter the position of the anterior fulcrum line and so simplify removable partial denture design. Complicated tooth-tissue-supported designs are thus transformed into much simpler tooth-supported removable partial overdentures.

Occlusal requirements for implant prosthodontics, as well as the advantages and disadvantages of two occlusal schemes are discussed. Based on the requirements of fixed reconstruction, the concept of lingualized occlusion with anterior guidance is presented as an ideal occlusal scheme for many implant cases. It embodies the established requirements for fixed implant prosthesis, eases fabrication, and simplifies intraoral adjustment procedures.

Two brands of latex rubber gloves and one brand of polyvinyl chloride glove were examined for their permeability. New and used gloves were included. All of the gloves were examined visually and then subjected to an air leakage test, an electrical test, and a microbiologic test. Permeability was evaluated independently by two researchers in a blind manner. Statistical analysis showed that there were no significant differences among the three brands of gloves or with respect to the usage periods, according to visual inspection and the air leakage test. Conversely, there were significant differences among each of the three brands of gloves and with respect to usage periods, according to the electrical and microbiologic tests

Wear and marginal quality of 14 mesio-occlusodistal amalgam restorations (Dispersalloy) were quantitatively analyzed in this in vivo study. Wear rates, measured as maximu m vertical loss of substance in the occlusal contact area, were 41, 50, 57, 79, 82, 123, 165, and 215 um after 1, 2, 3, 6, 9, 24, 36, and 48 months, respetively. In the contact-free occlusal area an expansion of 2 to 9 um was recorded. The micromorphology of the tooth-amalgam interface significantly changed within the first 9 months after restoration placement. The percentage of marginal opening increased from 91% to 100%, marginal restoration fracture from 49% to 89% and underfilled margin from 50% to 78%. Amalgam restorations have clinically proved successful despite their poor marginal adaptation and their inferior wear resistance compared to enamel. Thus, the wear resistance of amalgam substitutes, preferably metal-free, tooth-colored restorative materials, would not necessarily have to exceed that of amalgam to replace it. The wear data generated may serve as guiding figures in the development of amalgam substitutes.

Endodontically treated premolars may discolor with time, impairing the esthetic appearance. Frequently combined with large defects, they are subject to an increased risk of fracture. The restoration of such teeth with a cast post and core and a separate porcelain-fused-to-metal crown results in additional loss of intact tooth structure. A case is presented in which the cavity of a discolored, pulpless maxillary premolar was restored, without further loss of tooth cavity substance, with an adhesively luted porcelain inlay after intracoronal bleaching, a technique traditionally used to lighten discolored, pulpless anterior teeth.

Eight maxillary anterior teeth with severe palatal erosion in an anorexic patient were restored with oxidized gold veneers and without tooth preparation. Because of the extensiv e exposure of dentin, a cement based on 4-methacryloxyethyl trimellitate anhydride was used as the luting agent.

Six standard mesio-occlusodistal restorations in extracted mandibular human molars and six opposing palatal cusps from maxillary human first molars were prepared per group. The occlusal contact areas of the restorations and of the opposing enamel cusps were digitized with a three-dimensional scanner. The specimens were exposed to a clinically correlated long-term in vitro wear test. Dicor MGC, Cerec Vita Mk I porcelain, Cerec Vita Mk II V7R porcelain, and Cerec Mk II Vita V7K porcelain were tested. The mean wear of these ceramic materials at the end of the long-term test ranged from 24.3 ± 10.3 um (Cerec Vita Mk II V7R) to 88.0 ± 37.3 um (Dicor MGC). The mean wear of the oppoisng human enamel cusps ranged from 93.5 ± 30.8 um (Cerec Vita Mk II V7R) to 224.3 ± 117.4 um (Cerec Vita Mk I). All ceramic materials except Dicor MGC wore less than did previously measured standards, such as natural human enamel and amalgam. However, because the wear of opposing enamel cusps was high with Dicor MGC and with Cerec Vita Mk I the total wear of these two materials-the sum of the restoration's and the opposing tooth's wear-was higher than that of the standards. Only the new fine porcelain Cerec Vita Mk II V7R showed a total wear comparable to that of enamel, because of its moderate abrasivity against opposing enamel. The wear of the two luting composite resins was measured at the end of the test. Both luting composite resins wore more than did the ceramic inlays and surrounding enamel, leaving a shallow ditch around the restorations.

Numerous investigators have reported patients' postcementation sensitivity with glass-ionomer luting agents. This information has been predominantly anecdotal and unsupported by data. This paper reports on the actual perceptions of patients who had restorations cemented with both glass-ionomer and zinc phosphate luting agents. Forty-five patients were randomly selected and received two cast restorations, one cemented with glass-ionomer cement and the other with zinc phosphate cement, also by random assignment. After 1 week, patients returned to complete a self-administered evaluation of perceived sensitivity. Neither luting agent resulted in greater sensitivity when used according to its manufacturer's instructions.

The cohesive plateau theory states that the strength at a bonded interface should equal the strength, cohesively, of the substrate with which it is bonded. A new method was developed to test cohesive strength of dentin so as to offer an opportunity to compare the data against shear bond strength values of commercially available dentinal bonding agents using the same test assembly. The method applied a shear force to a standard circular column of dentin continuous with the tooth from which it was cut with a tubular diamond drill. The mean cohesive strength of dentin in the shear mode, based on 30 specimens, was 36.18 ± 6.81 MPa.