Evidence-Based Dentistry Evidence on implant dentistry Background.—The success of implant dentistry has changed the focus of treatment away from avoiding tooth extraction as a method of last resort and toward providing tooth substitutes that may yield results equal or superior to retaining natural teeth. The long-term implications of implant treatment are not yet fully understood, making caution a wise choice. Several perspectives on implant dentistry were explored. Form.—Particularly in the anterior dentition, esthetic failures are far more common than mechanical failures in implant dentistry. Patient dissatisfaction with the implant can occur when the dentist does not consider the esthetic risk factors of high patient expectations, a high smile line, poor gingival quality, poor papillary morphology, and low bone height. The practitioner must also consider how to achieve esthetic soft tissue contours, which requires careful assessment of the relationship between the final restoration and surrounding bone height, a determination of whether existing bone morphology is adequate for the implant requirements, and careful development of the implant site. Function.—Natural teeth and well-osseointegrated implants differ significantly in the lack of a periodontal ligament (PDL) with the implant. As a result, there is no PDL cushioning effect or proprioceptive ability, both of which can affect the survival of the implant. Treatment protocols therefore call for restoring posterior single-unit implants slightly out of occlusion to compensate for the axial compression of the PDL in the adjacent natural teeth with loading. The lack of a PDL also means the lack of regenerative potential, limiting the ability for repair disruptions of any of the osseointegration. In itself, the lack of a PDL may put implants at greater risk for eventual loss than natural teeth, particularly in patients who are prone to periodontal disease. Survival.—The performance of endodontic treatment has been enhanced by the ability to use microscopes, titanium files, computerized apex locators, and ultrasonic instruments, yielding greater precision and efficiency, fewer errors, and better success rates than were previously achieved. A 3-year success rate for endodontic treatment in addressing pulpal or periapical disease of up to 98% has
been reported. Long-term, the survival rate for endodontically treated teeth is lower, with a reported 10-year survival of just under 90%. In comparison, few data are available to assess implant success rates over these long periods. Single-unit implant-retained restorations have the potential to have long-term success rates comparable to those for endodontically restored teeth. Implant survival is negatively affected by risk factors such as poor patient oral hygiene, poor alveolar bone quality, and smoking, but the actual extent to which these factors affect implant survival is as yet undetermined. Advances in periodontal regenerative therapy to reverse loss of supporting alveolar bone used along with conventional periodontal therapies (pocket reduction surgery, root resection, and hemisection) also offer patients potential benefits for maintaining compromised teeth for a longer time. Complications.—Mechanical complications such as failure of the prosthesis (for example, porcelain fracture) or failure of a component of the implant (for example, the abutment screw) have been noted in up to 17% of implant prostheses in the first 5 years of use. Surgical procedures are required to prepare the implant site and place the implant, carrying the same risks as for any surgical procedure, specifically, hemorrhage, neurosensory disorders, and devitalization of adjacent teeth. Complications specific to implants include failure of osseointegration, which can occur early or late in the process. Early failures reflect the unsuccessful osseointegration of the implant and most often result from impaired healing ability of the host bone site, disruption of a compromised bone-to-implant interface after the abutment connection, or infection. These implants must be removed and the site must heal before further treatment is considered. Late failures occur after successful osseointegration has been lost and usually result from occlusal overload and/or bacterial growth that produces periimplantitis. Supportive measures have been used to manage failing implants, but their effectiveness has not been rigorously studied. Conventional treatments to preserve dentition also incur risks, but most do not lead to failure or can be managed successfully with surgical or nonsurgical retreatment. Quality of Life.—The higher cost associated with implant therapy must be weighed against improved quality of
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life. The commonly held perception is that implants provide a better quality of life than conventional treatments, but little evidence supports this belief. A greater improvement in quality of life measures has been linked to the use of implants to anchor removable prostheses than when they are used as a single-tooth replacement or other form to restore a bounded edentulous space. Discussion.—Short-term data collected under optimal conditions that may not be achievable in a private practice have supplied the majority of the support for using singleunit implants to replace natural teeth. Currently, the lack of standardized outcome evaluations has hindered the ability to compare implant and tooth preservation therapies. Implant dentistry is recognized as having great potential, but more data are needed to inform practitioners making decisions about implant technology.
Clinical Significance.—With some justification, much has been written about the success of implants. Controlled studies comparing implant results with more traditional restorative concepts are lacking. Presented is a discussion of treatment impact on Form, Function, Survival, Management of Complications, and Quality of Life.
Tang CS, Naylor AE: Single-unit implants versus conventional treatments for compromised teeth: A brief review of the evidence. J Dent Educ 69:414-418, 2005 Reprints available from C Tang, Univ of North Carolina School of Dentistry, Student Mailboxes 006-065, CB #7450, Chapel Hill, NC 27599-7450; fax: 919-966-5795; e-mail: [email protected]
General Dentistry Microleakage of caries-detecting dyes Background.—Caries-detecting dyes provide an objective measure of carious dentin remaining after removal procedures have been completed. They stain infected, demineralized outer dentin but should not stain healthy inner dentin. Measuring microleakage as the criterion, an in vitro investigation looked at the effect of residual cariesdisclosing dyes on a dentinal adhesive system and accompanying resin composite. Methods.—Sixty teeth had circular preparations cut on the facial or lingual surface, then caries-disclosing dyes were applied. Treatment with 35% phosphoric acid etchant, application of a Single-Bond adhesive, and insertion of Z-100 hybrid resin composite followed. After thermocycling and sealing with nail varnish, the teeth were immersed in methylene blue dye, invested in acrylic resin, labeled, and sectioned to determine whether leakage was present based on the penetration of the dye at the occlusal and gingival surface positions (Fig 4). The 6 dye pretreatment groups into which the teeth were placed were treated with Caries Detector (group 1), Carid-tect (group 2), Seek (group 3), Snoop (group 4), To Dye For (group 5), and no pretreatment (group 6—control).
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Results.—The group exposed to To Dye For had significantly greater leakage than that exposed to Snoop at the occlusal surface (Table 2). All of the groups except that pretreated with Snoop and the control group had significantly greater leakage at the gingival surface position.
Fig 4.—Occlusal and gingival surface positions. Note that the surface area of enamel is greater at the occlusal than the gingival position. (Courtesy of Owens BM, Lim DY, Arheart KL: Effect of residual caries-disclosing solutions on microleakage of a dental adhesive system. Quintessence Int 36:169-176, 2005.)