In this issue of JCDA Express, the topics covered are therapy for obstructive sleep apnea, the cost of premature restorative failures, pregnancy and oral health, and the impact of crowns on periodontal tissues. JCDA gratefully acknowledges the generosity of the publishers of the selected articles, who have granted free access to the full-text papers until July 8, 2010. To find out more about the publications featured in JCDA Express, follow the links in the Notes and News sidebar.

Previous issues of JCDA Express can be found on our newly redesigned website at JCDA.ca. I invite you to take a tour of the site to see the improvements we have made: an updated look, easier navigation and more clinical content tailored to the needs of Canadian dental professionals. I hope you find the new JCDA.ca interesting and useful. Please contact me with your comments, suggestions and criticisms.

Yours sincerely,

Dr. John P. O'Keefe
Editor-in-chief
jokeefe@cda-adc.ca

Dr. Peter Cooney is Chief Dental Officer, Health Canada. Dr. Cooney recommends:

Oral appliances for treatment of snoring and obstructive sleep apnea: a review of clinical-effectiveness. Canadian Agency for Drugs and Technologies in Health. Health Technology Inquiry Service Report. Edmonton, Alberta.
20 April 2009.

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Key points:

• The literature showed that, when compared with inactive devices or pretreatment, mandibular advancement device (MAD) therapy is effective in improving sleep disordered breathing and quality of life in snoring and obstructive sleep apnea (OSA) patients. Custom MAD were significantly more effective than prefabricated MAD (60% vs. 31%). There was no evidence that inactive (non-advancement) devices were effective.
• Compliance for MAD therapy was high in the included studies, and patients who were compliant tended to be long-term users.
• No serious adverse events associated with MAD therapy were reported in the literature, but occlusal changes were noted over a long period of use.
• Both MAD and continuous positive airway pressure (CPAP) treatments improved sleep outcomes, but CPAP was found to be more effective.
• Compared with upper airway surgery, MAD therapy appeared to be more effective over long-term use; thus MAD may be a simpler alternative to CPAP and surgery.
• Recent systematic reviews and meta-analyses recommend the prescription of MAD therapy to patients with mild to moderate OSA, and those patients who are unwilling or unable to tolerate CPAP therapy.

Reasons for recommending this article:

The report provides an objective systematic review of the literature and gives valuable insights to the dentist interested in providing treatment for OSA and snoring patients.

The report was prepared for the Federal Dental Care Advisory Committee, a committee of oral health professionals who provide advice to the Office of the Chief Dental Officer and to the 6 federal departments that directly provide dental services to clients.

Dr. Terry Donovan is chair of biomaterials in the department of operative dentistry, University of North Carolina at Chapel Hill School of Dentistry.
Dr. Donovan, a JCDA editorial consultant, recommends:

Spear FM. The risk of the metal-free practice!
J Esthet Restor Dent. 2009;21(2):71-4.

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Key points:

Dr. Frank Spear is recognized as one of the premier postdoctoral educators in reconstructive and interdisciplinary dentistry in the world. In this article, Dr. Spear documents his experiences using an unproven ceramic material (Willi’s Glass), which was exceptionally esthetic but failed to withstand the functional occlusal forces in the mouth. Dr. Spear’s knowledge of esthetic restorative materials is extensive, and dentists reading about his experience will gain valuable insight into the selection of ceramic systems.

• The author quantifies the financial costs of the premature failure of restorations. He also discusses the emotional and other subjective consequences of failed restorations.
• The author’s experience graphically illustrates the risks of following a “guru’s” philosophy in the absence of scientific validation.
• The article underscores the critical importance of waiting for evidence from clinical trials before using new materials.
• Finally, the article highlights the responsibility of speakers who might endorse or condemn products to have adequate evidence before sharing their opinions.

Reasons for recommending this article:

I believe dentists should read this article because it clearly delineates the fiscal and emotional costs of replacing restorations that fail prematurely because of deficiencies in the material. The article also highlights the necessity of waiting for data from independent clinical trials 3 to 5 years in length before using any new ceramic material. If clinicians are mindful of these points, they will avoid many costly disappointments.

Clinicians should follow the late Dr. Peter Schärer’s guidelines regarding all-ceramic crowns: data from clinical trials of 5 years should reveal success rates of 95% or better before using any new all-ceramic system. In vitro trials comparing physical properties are not predictive of clinical performance.

Clinicians must not underestimate the fact that objective and subjective costs of premature restorative failures are real and profound.

Dr. Clive Schneider-Friedman is an adjunct professor in the division of orthodontics and pediatric dentistry at the Schulich School of Medicine and Dentistry, University of Western Ontario. Dr. Schneider-Friedman, a member of CDA’s Committee on Clinical and Scientific Affairs, recommends:

Oral health during pregnancy and early childhood: evidence-based guidelines for health professionals. California Dental Association Foundation. Sacramento, California. February 2010.

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Key points:

Representatives from the California Dental Association and the American College of Obstetricians and Gynecologists worked together to produce these guidelines after a thorough review of the scientific literature and recent research.

The guidelines:

• provide an evidence-based resource on the treatment of oral disease in expectant mothers
• address many of the misconceptions about women undergoing dental treatment during the perinatal period (for example, the guidelines found no link between performing dental procedures in the first trimester of pregnancy and spontaneous abortion)
• discuss the importance of controlling oral disease before and during pregnancy and the impact of reducing pathogenic bacteria for the newborn (the guidelines found that providing optimal oral care for pregnant women can reduce the bacterial load in the mother and therefore reduce the severity of bacterial transmission to the newborn)
• include studies that demonstrate the impact of poor oral care during the perinatal period and the effect on the mother’s overall health
• provide information on the importance of timely oral care for pregnant women and describe how the benefits of care outweigh the risks of not providing care

Reasons for recommending this article:

Pregnancy can be a “teaching moment,” according to the guideline authors. The main messages presented in this document can be used to encourage expectant mothers to consider dental hygiene or treatment as part of their oral health routine prior to the birth of their baby.

As gatekeepers of the long-term oral health of their patients, dentists can use these guidelines to dispel some of the myths that persist about women undergoing dental treatment during pregnancy (e.g., avoiding dental radiographs or the use of local anesthesia). The guidelines provide valuable insight into current evidence-based literature on appropriate care and interventions that can dramatically improve the oral health of both mothers and babies.

Dr. Asbjørn Jokstad is head of prosthodontics at the University of Toronto faculty of dentistry. Dr. Jokstad, a JCDA editorial consultant, recommends:

Kosyfaki P, Pinilla Martin Mdel P, Strub JR. Relationship between crowns and the periodontium: a literature update.Quintessence Int. 2010;41(2):109-22.

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Key points:

• 18 clinical studies with observation times up to 10 years report on the impact of location of the crown margin on periodontal tissues. Supragingival margins remain the most advantageous from the periodontal point of view.
• 12 studies with observation times up to 5 years report on the impact of marginal fit on periodontal tissues. Even with a highly precise crown fitting, an intensive oral hygiene regimen must be undertaken if crown margins are placed subgingivally, to control gingival inflammation.
• 17 studies with observation times up to 6 years report on the impact of crown material on periodontal tissues. Polished gold and ceramic had the lowest microbial plaque accumulation, but correlation of these results with long-term outcomes is unclear. It should be noted that this review concentrates on conventional crown preparations and not on partial and complete ceramic veneers, where retaining an enamel bond for the polymer cement is the absolute prerequisite for minimizing marginal discoloration and secondary caries.
• No studies on crowns manufactured with CAD-CAM technology or using digital impression techniques were included. Given the promising data from in vitro studies showing consistently excellent marginal fit with these systems, we can hope for a new generation of prostheses where operator and fabrication factors will be minimized.
• No studies have focused on the margin placement on enamel vs. cement, irrespective of crown lengthening. Given the differences between the 2 tissues with regard to caries resistance and cement mechanism, crown margins should preferably be placed in enamel and not in cement. This should be a future avenue for clinical research considering the current trend of patients wanting bigger, longer and whiter ceramic teeth.
• Determining where to place the crown margins is sometimes a trade-off between creating an adequate ferrule, allowing an inspection of the marginal fit and maintaining adequate control during the cementation process. This review does not provide any guidance on which factor is the most crucial, although it does mention crown lengthening and forced eruption as possible interventions.

Reasons for recommending this article:

This paper provides a good summary of the studies that have attempted to relate crown therapy to periodontal health. The text is easy to read and presents human data supplemented by data from animal studies. One of the stated objectives of the review was to examine whether established knowledge had changed over the past 30 years. The authors conclude that this is not the case.

Commentary:

I was involved in a longitudinal study of 15- and 25-year outcomes for patients with crowns and dental bridges.^1,2 The latter report focused mainly on periapical outcomes because, by then, the margins were mostly located supragingivally. An added consideration in the debate about the relationship between crown margins and the periodontium is that, with time, a combination of tooth wear, passive eruption and apical migration of the gingiva in a more or less aggressive environment will bring the crown margins further away from the periodontium.³ The event rates of these 3 physiological phenomena are difficult to predict on an individual basis.

References

1. Valderhaug J, Ellingsen JE, Jokstad A. Oral hygiene, periodontal conditions and carious lesions in patients treated with dental bridges.
   A 15-year clinical and radiographic follow-up study. J Clin Periodontol. 1993;20(7):482-9.
2. Valderhaug J, Jokstad A, Ambjørnsen E, Norheim PW. Assessment of the periapical and clinical status of crowned teeth over 25 years. J Dent. 1997;25(2):97-105.
3. Newman HN. Attrition, eruption, and the periodontium. J Dent Res. 1999;78(3):730-4.

JCDA is the authoritative written voice of the Canadian Dental Association providing dialogue between the national association and the dental community. It is dedicated to publishing worthy scientific and clinical articles and informing dentists of issues significant to the profession.

NOTES AND NEWS

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CHECK OUT THE PUBLICATIONS FEATURED IN THIS ISSUE

Journal of Esthetic and Restorative Dentistry (publisher: Wiley-Blackwell)

Quintessence International (publisher: Quintessence Publishing)

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Dr. John P. O'Keefe
Editor-in-chief, JCDA
jokeefe@cda-adc.ca