Conclusion The current best evidence indicates that a glass ionomer cement has a significantly lower risk of loss of a NCCL restoration compared to either a three-step etch- and -rinse or a two-step etch- and -rinse adhesive system ; a three-step etch- and -rinse adhesive system has a significantly lower risk of loss of a NCCL restoration compared to a two-step etch- and -rinse adhesive system .
No significant difference could be observed in the risk of loss of a tooth-colored NCCL restoration between a three-step etch- and -rinse adhesive system and either a two-step self-etch or a one-step self-etch adhesive system
Objectives The aim of this review was to assess the effect of different adhesive systems and tooth preparation on the retention of tooth-colored restorative material s  placed in non-carious cervical lesions ( NCCLs ) .
Recommendations for conducting controlled clinical studies of dental restorative materials
About 35 years ago , Ryge provided a practical approach to evaluation of clinical performance of restorative material s. This systematic approach was soon universally accepted . While that methodology has served us well , a large number of scientific method ologies and more detailed questions have arisen that require more rigor . Current restorative material s have vastly improved clinical performance and any changes over time are not easily detected by the limited sensitivity of the Ryge criteria in short term clinical investigations . However , the clinical evaluation of restorations not only involves the restorative material per se but also different operative techniques . For instance , a composite resin may show good longevity data when applied in conventional cavities but not in modified operative approaches . Insensitivity , combined with the continually evolving and non-st and ard investigator modifications of the categories , scales , and reporting methods , has created a body of literature that is extremely difficult to meaningfully interpret . In many cases , the insensitivity of the original Ryge methods is misinterpreted as good clinical performance . While there are many good features of the original system , it is now time to move to a more contemporary one . The current review approaches this challenge in two ways : ( 1 ) a proposal for a modern clinical testing protocol for controlled clinical trials , and ( 2 ) an in-depth discussion of relevant clinical evaluation parameters , providing 84 references that are primarily related to issues or problems for clinical research trials . Together , these two parts offer a st and ard for the clinical testing of restorative material s/ procedures and provide significant guidance for research teams in the design and conduct of contemporary clinical trials . Part 1 of the review considers the recruitment of subjects , restorations per subject , clinical events , validity versus bias , legal and regulatory aspects , rationale s for clinical trial design s , guidelines for design , r and omization , number of subjects , characteristics of participants , clinical assessment , st and ards and calibration , categories for assessment , criteria for evaluation , and supplemental documentation . Part 2 of the review considers categories of assessment for esthetic evaluation , functional assessment , biological responses to restorative material s , and statistical analysis of results . The overall review represents a considerable effort to include a range of clinical research interests over the past years . As part of the recognition of the importance of these suggestions , the review is being published simultaneously in identical form in both the “ Journal of Adhesive Dentistry ” and the “ Clinical Oral Investigations . ” Additionally an extended abstract will be published in the “ International Dental Journal ” giving a link to the web full version . This should help to introduce these considerations more quickly to the scientific community
Conclusion The current best evidence indicates that a glass ionomer cement has a significantly lower risk of loss of a NCCL restoration compared to either a three-step etch- and -rinse or a two-step etch- and -rinse adhesive system ; a three-step etch- and -rinse adhesive system has a significantly lower risk of loss of a NCCL restoration compared to a two-step etch- and -rinse adhesive system .
No significant difference could be observed in the risk of loss of a tooth-colored NCCL restoration between a three-step etch- and -rinse adhesive system and either a two-step self-etch or a one-step self-etch adhesive system
Objectives The aim of this review was to assess the effect of different adhesive systems and tooth preparation on the retention of tooth-colored restorative material s  placed in non-carious cervical lesions ( NCCLs ) .