- Email: [email protected]
Dental liners with amalgam
Research Perspectives Industry sponsorship Background.—The question was posed whether scientific articles funded in part or whole by implant companies are likely to report lower annual failure rates with implants than articles not sponsored by this industry. Data were obtained from Medline and the Cochrane Database of systematic reviews, along with hand searches of 12 dental journals. Five systematic reviews were analyzed, with 41 trials chosen for assessment. Findings.—Mean annual failure rate for implants overall was 1.09%. For non–industry-funded trials, the mean annual failure rate was 2.74%. Four trials had nonindustry funding, 26 trials had no indication of funding source, and 27 had a risk of bias. Both industry-associated and unknown funding source trials had lower annual failure rates than non–industry-associated trials. Two trials included a conflict of interest statement. Thus, the probability of annual implant failure was significantly lower in trials sponsored in part or wholly by industry compared with trials sponsored by nonindustry sources. The bias may significantly influence tooth extraction decisions, research on tooth extraction, and health care policies set by government agencies. Analysis.—Companies that promote their products or services to clinical dentists leave evidence of their influence at trade shows, in trade journals, and in continuing education courses. Industry sponsorship of research can range from total control to providing funding after an independent researcher has conceived and completed a study. Because of the potential for a conflict of interest, caution is needed when considering the results of the research in either case. Indications are that industry-sponsored research is 3 to 5 times more likely to report results favorable to industry than non–industry-funded research. With respect to dental implants, the annual failure rate was analyzed, including all the factors that may have had an effect on the outcome: publication year, journal’s impact factor, prosthetic design, periodontal status, number of dental
implants in the study, methodological quality of the study, presence of a statistical advisor, and financial sponsorship. Only implant-supported single tooth and fixed partial edentulous bridges were included. Regression analysis indicated that both prosthetic design and source of funding significantly affected the reported annual failure rates. The odds ratios of industry-associated trials or trials with unknown sponsorship reporting lower annual failure rates than non–industry-associated trials were 0.21 and 0.33, respectively. In addition, two-thirds of the primary studies were prone to bias because of other shortcomings. Yet, the important factor reported by industry-supported research— mean annual implant failure rate—was about one-third of the number reported by non–industry-sponsored research. Discussion.—The low failure rate of implants makes it unlikely that dentists will change their practices simply because many studies have bias or are industry-supported in some way. However, it makes it clear that one must consider the results reported in light of who is paying the bills.
Clinical Significance.—All research should be conducted and reported in an open and aboveboard manner, but realistically we have to deal with many influences along the way to publication. None of them should make us compromise the findings. We need to be aware of the potential influences and carefully scrutinize what we read for what is not always obvious.
Balevi B: Industry sponsored research may report more favourable outcomes. Evid Based Dent 12:5-6, 2011 Reprints not available
Restorative Dentistry Dental liners with amalgam Background.—Dental amalgams cannot bond to dental tissue, leaving a gap that can attract a buildup of waste products of the dental amalgam. Microleakage from the tooth
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Dental Abstracts
and restoration interface may contribute to symptoms experienced by patients after amalgam restorations are placed, such as postoperative sensitivity. The effectiveness
of various dental liners used under amalgam restorations was investigated.
copal varnish and with calcium hydroxide; and (5) amalgam with glass ionomer and with calcium hydroxide.
Methods.—A single systematic review was found in a search of PubMed and the Cochrane Library databases. Randomized controlled trials (RCTs) comparing the use of a lining under amalgam restorations or the use of no lining or comparisons of various materials were also sought, with eight RCTs identified.
Comparisons of amalgam restorations with liners and bases versus bonded amalgam produced limited or inconclusive data. The quality of the studies was low, with small sample sizes that made it difficult to identify consistent significant differences. No definitive recommendation can be made to favor bonded amalgam or one of the dental liners for reducing postoperative sensitivity.
Results.—The systematic review evaluated bonded amalgam restorations and nonbonded amalgam restorations in 31 patients with 113 restorations. There was no significant difference in postoperative sensitivity, and the evidence was considered inadequate to conclusively favor bonded over nonbonded restorations.
Discussion.—The studies currently available concerning the efficacy of various dental liners for use with amalgam restorations to reduce postoperative sensitivity are insufficient to permit the formation of recommendations.
The RCTs compared a range of liners with each other or with a control group or bonded amalgam. Amalgam restorations with copal varnish produced less postoperative sensitivity than amalgam restorations without liners. Amalgam restorations with no liners were also compared with restorations with calcium hydroxide, modified glass ionomer liner, and fluoridated desensitizing agent. No consistent significant findings were uncovered. The data were judged inadequate to provide a definitive conclusion.
Clinical Significance.—More well-conducted RCTs are needed to address the question of which approach is best with amalgam restorations. A systematic review would be an appropriate way to synthesize the findings of these studies.
Comparisons of amalgam restorations with various liners and bases yielded limited or inconclusive data. There were no significant differences that occurred consistently. The combinations addressed were (1) amalgam with glass ionomer liner and amalgam with copal varnish; (2) amalgam with copal varnish and with a fluoridated desensitizing agent; (3) amalgam with glass ionomer and calcium hydroxide and with zinc phosphate and calcium hydroxide, with the latter only used for deep cavities; (4) amalgam with
Nasser M, Nield H: Evidence summary: Which dental liners under amalgam restorations are more effective in reducing postoperative sensitivity? Br Dent J 210:533-537, 2011 Reprints available from Z Powell, Shirley Glasstone Hughes Trust Fund Administrator, British Dental Assoc, 64 Wimpole St, London, W1G 8YS; e-mail: [email protected]
Ceramic veneers Background.—Patients are demanding improved esthetics in tooth restorations, which has led to the use of ceramic laminate veneers to enhance their smile. Clinical survival rates for ceramic veneers are about 93% after 15 years, a reflection of conservation of tooth structure, reliable bonding to enamel, good esthetics, and color stability. Factors that affect long-term survival include tooth surface, ceramic thickness, type of cement used, tooth morphology, aberrant function, and geometry of the preparation. Preparation designs fall into four types: window preparations, which are limited to the labial surface; feathered incisal edge preparations that are extended to
the incisal margin but lack a definite finish line; incisal shoulder finish line preparations; and overlapped incisal edge preparations, which include a palatal chamfer. A shoulder finish line may be needed to prevent the occurrence of a ceramic laminate veneer and enamel margin with a thin edge. This shoulder finish line reduces stress concentration in the ceramic veneer. The addition of the palatal chamfer is controversial, with no consistent evidence to support its usefulness. Tooth preparation with ceramic laminate veneers can be challenging, necessitating the removal of healthy tooth structure to allow an esthetic match to adjacent teeth. Worn dentition restorations can
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Issue 3
2012
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implants in the study, methodological quality of the study, presence of a statistical advisor, and financial sponsorship. Only implant-supported single tooth and fixed partial edentulous bridges were included. Regression analysis indicated that both prosthetic design and source of funding significantly affected the reported annual failure rates. The odds ratios of industry-associated trials or trials with unknown sponsorship reporting lower annual failure rates than non–industry-associated trials were 0.21 and 0.33, respectively. In addition, two-thirds of the primary studies were prone to bias because of other shortcomings. Yet, the important factor reported by industry-supported research— mean annual implant failure rate—was about one-third of the number reported by non–industry-sponsored research. Discussion.—The low failure rate of implants makes it unlikely that dentists will change their practices simply because many studies have bias or are industry-supported in some way. However, it makes it clear that one must consider the results reported in light of who is paying the bills.
Clinical Significance.—All research should be conducted and reported in an open and aboveboard manner, but realistically we have to deal with many influences along the way to publication. None of them should make us compromise the findings. We need to be aware of the potential influences and carefully scrutinize what we read for what is not always obvious.
Balevi B: Industry sponsored research may report more favourable outcomes. Evid Based Dent 12:5-6, 2011 Reprints not available
Restorative Dentistry Dental liners with amalgam Background.—Dental amalgams cannot bond to dental tissue, leaving a gap that can attract a buildup of waste products of the dental amalgam. Microleakage from the tooth
162
Dental Abstracts
and restoration interface may contribute to symptoms experienced by patients after amalgam restorations are placed, such as postoperative sensitivity. The effectiveness
of various dental liners used under amalgam restorations was investigated.
copal varnish and with calcium hydroxide; and (5) amalgam with glass ionomer and with calcium hydroxide.
Methods.—A single systematic review was found in a search of PubMed and the Cochrane Library databases. Randomized controlled trials (RCTs) comparing the use of a lining under amalgam restorations or the use of no lining or comparisons of various materials were also sought, with eight RCTs identified.
Comparisons of amalgam restorations with liners and bases versus bonded amalgam produced limited or inconclusive data. The quality of the studies was low, with small sample sizes that made it difficult to identify consistent significant differences. No definitive recommendation can be made to favor bonded amalgam or one of the dental liners for reducing postoperative sensitivity.
Results.—The systematic review evaluated bonded amalgam restorations and nonbonded amalgam restorations in 31 patients with 113 restorations. There was no significant difference in postoperative sensitivity, and the evidence was considered inadequate to conclusively favor bonded over nonbonded restorations.
Discussion.—The studies currently available concerning the efficacy of various dental liners for use with amalgam restorations to reduce postoperative sensitivity are insufficient to permit the formation of recommendations.
The RCTs compared a range of liners with each other or with a control group or bonded amalgam. Amalgam restorations with copal varnish produced less postoperative sensitivity than amalgam restorations without liners. Amalgam restorations with no liners were also compared with restorations with calcium hydroxide, modified glass ionomer liner, and fluoridated desensitizing agent. No consistent significant findings were uncovered. The data were judged inadequate to provide a definitive conclusion.
Clinical Significance.—More well-conducted RCTs are needed to address the question of which approach is best with amalgam restorations. A systematic review would be an appropriate way to synthesize the findings of these studies.
Comparisons of amalgam restorations with various liners and bases yielded limited or inconclusive data. There were no significant differences that occurred consistently. The combinations addressed were (1) amalgam with glass ionomer liner and amalgam with copal varnish; (2) amalgam with copal varnish and with a fluoridated desensitizing agent; (3) amalgam with glass ionomer and calcium hydroxide and with zinc phosphate and calcium hydroxide, with the latter only used for deep cavities; (4) amalgam with
Nasser M, Nield H: Evidence summary: Which dental liners under amalgam restorations are more effective in reducing postoperative sensitivity? Br Dent J 210:533-537, 2011 Reprints available from Z Powell, Shirley Glasstone Hughes Trust Fund Administrator, British Dental Assoc, 64 Wimpole St, London, W1G 8YS; e-mail: [email protected]
Ceramic veneers Background.—Patients are demanding improved esthetics in tooth restorations, which has led to the use of ceramic laminate veneers to enhance their smile. Clinical survival rates for ceramic veneers are about 93% after 15 years, a reflection of conservation of tooth structure, reliable bonding to enamel, good esthetics, and color stability. Factors that affect long-term survival include tooth surface, ceramic thickness, type of cement used, tooth morphology, aberrant function, and geometry of the preparation. Preparation designs fall into four types: window preparations, which are limited to the labial surface; feathered incisal edge preparations that are extended to
the incisal margin but lack a definite finish line; incisal shoulder finish line preparations; and overlapped incisal edge preparations, which include a palatal chamfer. A shoulder finish line may be needed to prevent the occurrence of a ceramic laminate veneer and enamel margin with a thin edge. This shoulder finish line reduces stress concentration in the ceramic veneer. The addition of the palatal chamfer is controversial, with no consistent evidence to support its usefulness. Tooth preparation with ceramic laminate veneers can be challenging, necessitating the removal of healthy tooth structure to allow an esthetic match to adjacent teeth. Worn dentition restorations can
Volume 57
Issue 3
2012
163