Course Number: 108.1 Biofilm Formation and Caries Incidence With Removable Partial Dentures Authored by Eduardo Passos Rocha, DDS, MS, PhD, Eloá Rodrigues Luvizuto, DDS, MS and Suzi Fortuna Sabotto, DDS Upon successful completion of this CE activity 1 CE credit hour may be awarded A Peer-Reviewed CE Activity by Dentistry Today is an ADA CERP Recognized Provider. Approved PACE Program Provider FAGD/MAGD Credit Approval does not imply acceptance by a state or provincial board of dentistry or AGD endorsement. June 1, 2006 to May 31, 2009 AGD Pace approval number: 309062 Opinions expressed by CE authors are their own and may not reflect those of Dentistry Today. Mention of specific product names does not infer endorsement by Dentistry Today. Information contained in CE articles and courses is not a substitute for sound clinical judgment and accepted standards of care. Participants are urged to contact their state dental boards for continuing education requirements.
Biofilm Formation and Caries Incidence With Removable Partial Dentures LEARNING OBJECTIVES: After reading this article, the individual will learn: The effect of removable partial dentures (RPD) on biofilm formation and caries index. An oral hygiene regimen for patients who wear an RPD. ABOUT THE AUTHORS INTRODUCTION Dr. Rocha is assistant professor in the Department of Dental Materials and Prosthodontics, at the São Paulo State University s Araçatuba Faculty of Dentistry of Araçatuba (UNESP). He can be reached at eduardo_rocha@foa.unesp.br. Dr. Luvizuto is a PhD student in the Department of Integrated Clinic and Surgery at the São Paulo State University s Araçatuba Faculty of Dentistry of Araçatuba (UNESP). She can be reached at eloaluvizuto@hotmail.com.br. Dr. Sabatto is a Scientific Initiation Intern, Department of Dental Materials and Prosthodontics, at the São Paulo State University s Araçatuba Faculty of Dentistry of Araçatuba (UNESP). She can be reached at suzifortuna@ig.com.br. The removable partial denture (RPD) is indicated for patients with Kennedy class I and II occlusion, clinical situations that require a conventional prosthesis supported by teeth and soft tissues. However, RPDs have been the target of severe criticism related to associated deleterious effects on the supporting structures following placement. This criticism led to technical improvements in terms of adaptation of the RPD casting to the oral structures with adequate cast alloy passivity. Nevertheless, despite technological advances, RPDs continue to be associated with biofilm accumulation and the development of caries. 1-12 Tomlin and Osborne 13 reported carious lesions in teeth supporting RPDs and other teeth in the mouths of these patients, as well as periodontal disease with gingival recession. Carlsson, et al 14 analyzed periodontal health, tooth mobility, recession, tissue in-flammation, and caries incidence in patients with RPDs (48 patients with a maxillary complete denture and a mandibular RPD class I) 15 months after placement. The authors observed a high prevalence of periodontal disease and caries, both in teeth supporting the RPD and other teeth. In a followup study, the authors 15 observed progression of disease, including tooth extraction and caries more strongly associated with RPD support teeth. Recently, Rocha, et al 16 and Mihalow and Tinanoff 17 observed an increase in Streptococcus mutans in the saliva of RPD patients after prosthesis placement. This finding suggests that chemoprophylactic strategies need to be established for patients receiving RPDs to control and reduce biofilm formation and caries development, and thereby help to maintain the patient s oral health. 16,18 Rocha, et al 16 observed alterations in the caries index in RPD users with a higher caries index even in patients with a high level of cooperation and motivation for performing proper oral hygiene. Nevertheless, there are data showing the success of RPD treatment without chemical plaque control. 19-25 The purpose of this article is to review the literature regarding the technological development of the RPD, the effect of RPDs on biofilm formation and caries index, and the use of chlorhexidine as a chemoprophylactic agent for patients with an RPD. LITERATURE REVIEW Continuing Education Recommendations for Fluoride Varnish Use in Caries Management In the dental literature, several clinical studies have evaluated RPD treatment, 1,2,13-15,19,21,22,26,27 particularly in 1
regard to the effects on the periodontal complex. These studies are longitudinal evaluations, with periodic clinical and radiographic assessments. Studies conducted in the 1950s and 1960s usually reported severe damage to the periodontium, with varying degrees of bone loss and recession mainly in the abutment teeth. 13-15 Carlsson, et al 2 studied the periodontal status of 88 patients, divided into 5 groups: Group I mandibular RPD; Group II maxillary RPD; Group III patients without any type of denture; Group IV complete mandibular denture and maxillary RPD; and Group V patients who had replaced the old dentures with new dentures during the follow-up period. There were alterations in the periodontal status (gingivitis, tooth mobility, and bone loss) in all groups, but these were more evident in Group IV, with the teeth displaying greater mobility; 68% of RPD-supporting teeth had gingivitis and a significant number of teeth were extracted. This was not observed in Group III. The authors concluded that oral hygiene was of primary importance for maintaining oral health when an RPD was present, and was the most important factor for successful RPD treatment. Further, it has been observed that after informing patients about the importance of biological concepts associated with RPD treatment, 1,13,28, and informing patients of the importance of performing appropriate oral hygiene 21,22, it was possible to change the outcome and maintain a healthy oral cavity for long periods of time. 25 Bergman, et al 21 believe that it is possible for patients with RPDs to be cooperative and maintain oral health. In their study of patients with RPDs, no significant periodontal changes were found, and the incidence of caries was only 8% of the healthy tooth surfaces over a 10- year follow-up period. The authors credit these results to the careful conventional oral hygiene program instituted with the patients without chemical control or any additional technique. This study does not support the concept that an RPD itself will increase the incidence of caries or periodontal disease. However, it has been reported that the presence of a prosthesis in the oral cavity promotes the conditions for establishment and accumulation of microorganisms, as is seen for natural teeth. 17 Moreover, the presence of a prosthesis in the oral cavity increases the retention sites for microorganisms; this is particularly the case with an RPD, which has a design that favors food retention, biofilm accumulation, 5,9,10 and colonization of microorganisms such as S. mutans. 16,17,29 Biofilm formation has been observed on teeth in close contact with the RPD, either the artificial tooth or the resin base, or even below the clasp arms and the minor connectors. The proximal surfaces of natural teeth are at higher risk for biofilm accumulation, followed by the lingual or palatal surfaces. In the absence of an RPD, biofilm accumulation on the tooth surfaces adjacent to an edentulous space is lower. 3,5,7,9-11,23,30-33 Other studies have monitored oral hygiene by analyzing the quantity of biofilm on dental surfaces, as indicated by the plaque index or by its effects on the gingival tissues. 34-36 This can provide data for encouraging patients to maintain good oral hygiene. Since effective oral hygiene has been shown to be associated with a low incidence of periodontal disease and caries for patients with an RPD, preventive practices for these patients can be suggested. 16,37 Chlor\hexidine gel has proven to be effective and safe as a plaque control agent, since chlor\hexidine is a cationic detergent with strong antimicrobial action against Gram-positive and Gram-negative bacteria, and fungi. It can be used at a high concentration, and due to the van der Waals forces, chlorhexidine can link to anionic groups in the oral cavity and thus be continuously sustained at therapeutic levels. 38 In gel form, some of the undesirable side effects observed after using long-term chlorhexidine rinse protocols are not observed, such as staining of resin restorations and artificial teeth, and irritation of the tongue. However, burning sensation of the mucous membranes and taste disturbances were observed after using the gel form. These side effects disappear within 48 to 72 hours, as observed by Rocha, et al. 16 Further, similar to Rocha, et al 16 and contrary to the findings of Bergman, et al 22, Bassi, et al 11 showed that most patients are unable to maintain a high level of oral hygiene by mechanical means, reinforcing the need for chemoprophylaxis to achieve effective control of biofilm development and prevention of caries. Similar findings 2
have been reported by others. 16,17,29 For example, Mihalow and Tinanoff 17 studied S. mutans in the saliva of patients with an RPD. They observed that after prosthesis placement microbial levels were higher in patients who, prior to RPD placement, had high S. mutans levels in saliva (> 105 CFU/mL of saliva). Considering the association between the use of RPDs and an increase in the plaque index, some authors 25,39,40 attribute prosthesis failure to the lack of adequate oral hygiene, and not to the specifics of treatment plan or simply the presence of the prosthesis. DISCUSSION Traditionally, treatment planning for an RPD has been based on biomechanical factors, with priority given to principles such as stability and retention. Nevertheless, RPD planning cannot be focused only on mechanical concerns, because this will not guarantee a successful outcome. The literature clearly emphasizes the need to consider basic principles of RPD design and preserve the oral structures, using bars and connectors to enchance the stability. However, the RPD design should avoid food retention and biofilm formation. When effective biomechanical principles can be established, some bars and connectors can be removed or modified in order to avoid small retentive areas close to abutment teeth. Considering the strong association between the use of RPDs, biofilm accumulation, and caries, oral hygiene concerns must be incorporated into the treatment plan. It is evident that attention to the preventive aspect of RPD treatment must include more than periodic check-ups. Prevention must be incorporated into the patient s daily routine. RPD users often have difficulty removing the biofilm, even under supervision and after being instructed in the correct use of a toothbrush and dental floss. This was demonstrated in a study 16 in which S. mutans levels in saliva increased significantly 48 days after prosthesis placement, with levels above 106 UFC/mL of saliva. Even if the importance of an effective oral hygiene regimen is stressed, certain RPD patients remain at risk for biofilm accumulation and the development of caries and periodontal disease. Included here are those who are ill or physically weakened. For those patients, the assistance of a second person (ie, home health aide) may be needed. The biofilm accumulation and caries index are influenced by the increase in hard surfaces in the mouth following placement of an RPD. As noted previously, there is an increase in microorganism-retentive areas with the presence of an oral prosthesis, specifically the acrylic resin base and metal structure of the RPD. Further, the high consumption of fermentable carbohydrates can lead to an increased caries incidence. Using a diet diary, one study observed that RPD users had high sugar consumption in addition to what was consumed in meals, making it difficult to control biofilm accumulation by conventional methods. 16 This is a particular concern in elderly patients, where the presence of gingival recession favors the development of root caries. The etiology of root caries is related to Lactobacillus spp, and indeed, one study observed that Lactobacillus was present in high numbers in patients with RPDs. 29 The situation will be aggravated if biofilm control is not effective, with reduction of the intraoral ph, placing the patient at risk for development of caries. 41 Therefore, it can be suggested that the RPD design should be as simple as possible, without affecting the basic principles of retention, stability, and reciprocity, and causing problems due to mechanical inefficiency. Further, it is believed that the use of chlorhexidine gel, in accordance with the protocol proposed by Maltz, et al 42 (described below), should be incorporated into the clinical protocol during RPD treatment. This gel is inexpensive, practical, and effective for caries reduction, 16 and it can reduce biofilm accumulation. The protocol is based on the use of chlorhexidine gel at a high concentration (1%) for a short time interval (2 days). This combination results in a drastic reduction in the number of microorganisms. The application of gel is with the aid of disposable molds, according to the following schedule: first session with 4 applications of 5 minutes at 5-minute intervals (ie, 5-minute waiting period between each 5-minute application), and 24 hours later, a second session with 3 applications of 5 minutes at 5-minute intervals. Prior to each application, both the prosthesis and the dental arch must be submitted to prophylaxis. 3
Prophylaxis is necessary, as the effect of chlorhexidine is reduced in the presence of bacterial plaque. Adoption of this protocol results in a drastic reduction in S. mutans in saliva, with undetectable levels 24 hours after application of the gel. The benefits last for up to 82 days in some patients, which is within the interval of 2 to 6 months, considered to be the duration of the beneficial effects of chlorhexidine. 43 Repetition of the protocol prolongs the effects of chlorhexidine. Nevertheless, the taste of chlorhexidine is bitter, therefore flavoring is needed. Sodium saccharine should be avoided, since it can interfere with the efficacy of chlorhexidine. 44 CONCLUSION RPD users can be considered at high risk for development of caries and periodontal disease, and RPD patients may not be able to maintain proper oral hygiene due to advanced age, physical disabilities, or poor motivation. Dental professionals must educate these patients and encourage them to maintain periodic recalls. Further, prophylactic procedures including the application of a chlorhexidine gel should be adopted by RPD users to help maintain a healthy mouth. REFERENCES 1. Anderson JN, Bates JF. The cobalt-chromium partial denture. A clinical survey. Br Dent J. 1959;107:57-62. 2. Carlsson GE, Hedegard B, Koivumaa KK. Studies in partial denture prothesis. IV. Final results of a 4-year longitudinal investigation of dentogingivally supported partial dentures. Acta Odontol Scand. 1965;23:443-472. 3. Asckar EM, Vieira LF, Bonachela WC. Estudo longitudinal de pacientes portadores de próteses parciais removíveis (PPR) em relação aos dentes controles, retentores primários e retentores secundários, com acompanhamento pro-fissional. Odontologia USF. 1999;17:63-77. 4. Petridis H, Hempton TJ. Periodontal considerations in removable partial denture treatment: a review of the literature. Int J Prosthodont. 2001;14:164-172. 5. Ghamrawy EE. Quantitative changes in dental plaque formation related to removable partial dentures. J Oral Rehabil. 1976;3:115-120. 6. Mojon P, Rentsch A, Budtz-Jorgensen E. Relationship between prosthodontic status, caries, and periodontal disease in a geriatric population. Int J Prosthodont. 1995;8:564-571. 7. Yeung AL, Lo EC, Chow TW, et al. Oral health status of patients 5-6 years after placement of cobalt-chromium removable partial dentures. J Oral Rehabil. 2000;27:183-189. 8. Vanzeveren C, D Hoore W, Bercy P. Influence of removable partial denture on periodontal indices and microbiological status. J Oral Rehabil. 2002; 29:232-239. 9. Addy M, Bates JF. Plaque accumulation following the wearing of different types of removable partial dentures. J Oral Rehabil. 1979;6:111-117. 10. Brill N, Tryde G, Stoltze K, et al. Ecologic changes in the oral cavity caused by removable partial dentures. J Prosthet Dent. 1977;38:138-148. 11. Bassi F, Mantecchini G, Carossa S, et al. Oral conditions and aptitude to receive implants in patients with removable partial dentures: a cross-sectional study. Part I. Oral conditions. J Oral Rehabil. 1996;23:50-54. 12. Rantanen T, Makila E, Yli-Urpo A, et al. Investigations of the therapeutic success with dentures retained by precision attachments. I. Root-anchored complete overlay dentures. Suom Hammaslaak Toim. 1971;67:356-366. 13. Tomlin HR, Osborne J. Cobalt-chromium partial dentures. A clinical survey. Br Dent J. 1961; 111:307-310. 14. Carlsson GE, Hedegard B, Koivumaa KK. Studies in partial dental prosthesis. II. An investigation of mandibular partial dentures with double extension saddles. Acta Odontol Scand. 1961;19:215-237. 15. Carlsson GE, Hedegard B, Koivumaa KK. Studies in partial dental prosthesis, III. A longitudinal study of mandibular partial dentures with double extension saddles. Acta Odontol Scand. 1962;20:95-119. 16. Rocha EP, Francisco SB, Del Bel Cury AA, et al. Longitudinal study of the influence of removable partial denture and chemical control on the levels of Streptococcus mutans in saliva. J Oral Rehabil. 2003;30:131-138. 17. Mihalow DM, Tinanoff N. The influence of removable partial dentures on the level of Strepto-coccus mutans in saliva. J Prosthet Dent. 1988; 59:49-51. 18. Keltjens HM, Schaeken MJ, van der Hoeven JS, et al. Effects of chlorhexidine gel on periodontal health of abutment teeth in patients with overdentures. Clin Oral Implants Res. 1991;2:71-74. 4
19. Bergman B, Hugoson A, Olsson CO. Periodontal and prosthetic conditions in patients treated with removable partial dentures and artificial crowns. A longitudinal two-year study. Acta Odontol Scand. 1971;29:621-638. 20. Bergman B, Hugoson A, Olsson CO. Caries and periodontal status in patients fitted with removable partial dentures. J Clin Periodontol. 1977; 4:134-146. 21. Bergman B, Hugoson A, Olsson CO. Caries, periodontal and prosthetic findings in patients with removable partial dentures: a ten-year longitudinal study. J Prosthet Dent. 1982;48:506-514. 22. Bergman B, Hugoson A, Olsson CO. A 25 year longitudinal study of patients treated with removable partial dentures. J Oral Rehabil. 1995; 22:595-599. 23. Schwalm CA, Smith DE, Erickson JD. A clinical study of patients 1 to 2 years after placement of removable partial dentures. J Prosthet Dent. 1977;38:380-391. 24. Bergman B, Ericson G. Cross-sectional study of patients treated with removable partial dentures with special reference to the caries situation. Scand J Dent Res. 1986;94:436-442. 25. Bergman B. Periodontal reactions related to removable partial dentures: a literature review. J Prosthet Dent. 1987;58:454-458. 26. Derry A, Bertram U. A clinical survey of removable partial dentures after 2 years usage. Acta Odontol Scand. 1970;28:581-598. 27. Kratochvil FJ, Davidson PN, Guijt J. Five-year survey of treatment with removable partial dentures. Part I. J Prosthet Dent. 1982;48:237-244. 28. Zarb GA, Mackay HF. The partially edentulous patient. I. The biologic price of prosthodontic intervention. Aust Dent J. 1980;25:63-68. 29. Narhi TO, Ainamo A, Meurman JH. Mutans streptococci and lactobacilli in the elderly. Scand J Dent Res. 1994;102:97-102. 30. Bissada NF, Ibrahim SI, Barsoum WM. Gingival response to various types of removable partial dentures. J Periodontol. 1974;45:651-659. 31. Runov J, Kroone H, Stoltze K, et al. Host response to two different designs of minor connector. J Oral Rehabil. 1980;7:147-153. 32. Chandler JA, Brudvik JS. Clinical evaluation of patients eight to nine years after placement of removable partial dentures. J Prosthet Dent. 1984;51:736-743. 33. Orr S, Linden GJ, Newman HN. The effect of partial denture connectors on gingival health. J Clin Periodontol. 1992;19:589-594. 34. Badersten A, Niveus R, Egelberg J. 4-year observations of basic periodontal therapy. J Clin Periodontol. 1987;14:438-444. 35. Greene JC, Vermillion JR. The oral hygiene index: a method for classifying oral hygiene status. J Am Dent Assoc. 1960;61:172-179. 36. Löe H. The gingival index, the plaque index and the retention index systems. J Periodontol. 1967;38:610-616. 37. Keltjens HM, Creugers TJ, Schaeken MJ, et al. Effects of chlorhexidine-containing gel and varnish on abutment teeth in patients with overdentures. J Dent Res. 1992;71:1582-1586. 38. Rolla G, Loe H, Schiott CR. The affinity of chlorhexidine for hydroxyapatite and salivary mucins. J Periodontal Res. 1970;5:90-95. 39. Berg E. Periodontal problems associated with use of distal extension removable partial dentures a matter of construction? J Oral Rehabil. 1985;12:369-379. 40. Tuominen R, Ranta K, Paunio I. Wearing of removable partial dentures in relation to periodontal pockets. J Oral Rehabil. 1989;16:119-126. 41. Davenport JC, Basker RM, Heath JR, et al. Removable partial dentures. 1. Need and demand for treatment. Br Dent J. 2000;189:364-368. 42. Maltz M, Zickert I, Krasse B. Effect of intensive treatment with chlorhexidine on number of Streptococcus mutans in saliva. Scand J Dent Res. 1981;89:445-449. 43. Emilson CG, Lindquist B, Wennerholm K. Recolonization of human tooth surfaces by Streptococcus mutans after suppression by chlorhexidine treatment. J Dent Res. 1987; 66:1503-1508. 44. Cury JA, Rocha EP, Koo H, et al. Effect of saccharin on antibacterial activity of chlorhexidine gel. Braz Dent J. 2001;11:29-34. 5
POST EXAMINATION INFORMATION Continuing Education To receive continuing education credit for participation in this educational activity you must complete the program post examination and receive a score of 70% or better. Traditional Completion Option: You may fax or mail your answers with payment to Dentistry Today (see Traditional Completion Information on following page). All information requested must be provided in order to process the program for credit. Be sure to complete your Payment, Personal Certification Information, Answers and Evaluation forms, Your exam will be graded within 72 hours of receipt.. Upon successful completion of the post-exam (70% or higher), a letter of completion will be mailed to the address provided. Online Completion Option: Use this page to review the questions and mark your answers. Return to dentalcetoday.com and signin. If you have not previously purchased the program select it from the Online Courses listing and complete the online purchase process. Once purchased the program will be added to your User History page where a Take Exam link will be provided directly across from the program title. Select the Take Exam link, complete all the program questions and Submit your answers. An immediate grade report will be provided. Upon receiving a passing grade complete the online evaluation form. Upon submitting the form your Letter Of Completion will be provided immediately for printing. General Program Information: Online users may login to dentalcetoday.com anytime in the future to access previously purchased programs and view or print letters of completion and results. POST EXAMINATION QUESTIONS 1. Carlsson, et al concluded that: a. oral hygiene is the most important factor for successful RPD treatment. b. oral hygiene is not the most important factor for successful RPD treatment. c. informing patients about the importance of oral hygiene can change RPD treatment outcome. d. Both a and c. 2. The following statement is TRUE: a. The presence of a prosthesis in the oral cavity decreases retention sites for microorganisms. b. The lingual surfaces of natural teeth are at the highest risk for biofilm accumulation. c. In the absence of an RPD, biofilm accumulation on tooth surfaces adjacent to an edentulous space is higher. d. The proximal surfaces of natural teeth are at highest risk for biofilm accumulation. 6 3. Chlorhexidine gel: a. is an anionic detergent. b. is a cationic detergent. c. is not effective against fungi. d. cannot be used in high concentration. 4. Side effects of chlorhexidine in gel form include: a. staining of resin restorations. b. irritation of the tongue. c. staining of artificial teeth. d. taste disturbances. 5. The following statement is TRUE: a. RPD planning must focus solely on mechanical factors to be successful. b. There is no proven association between RPDs and an increase in the plaque index. c. Side effects of chlorhexidine gel disappear within 48 to 72 hours. d. Side effects of chlorhexidine gel disappear within 12 hours. 6. The etiology of root caries is related to: a. Lactobacillus spp. b. S. Mutans. c. Pseudomonas aeroginosa. d. Yersinia enterocolitica. 7. The oral hygiene protocol suggested in this article uses a chlorhexidine gel concentration of: a. 0.02%. b. 0.1%. c. 0.5%. d. 1%. 8. The first session of the chlorhexidine gel oral hygiene protocol consists of: a. 2 applications of 5 minutes at 2-minute intervals. b. 4 applications of 2 minutes at 5-minute intervals. c. 4 applications of 5 minutes at 5-minute intervals. d. 3 applications of 2 minutes at 5-minute intervals
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