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Survival of removable dental prostheses
Badenoch-Jones EK, Lincoln T: Palatal injection for removal of maxillary teeth: Is it required? A systematic review. Int J Oral Maxillofac Surg 45:1283-1293, 3026
Reprints available from EK Badenoch-Jones, School of Medicine, The Univ of Queensland, Brisbane, Queensland, Australia; e-mail: [email protected]
Removable Prosthodontics Survival of removable dental prostheses Background.—Removable dental prostheses (RDPs) are a well-established option for treating moderately reduced dentition, but the evidence supporting their use is sparse. In addition, comparisons to fixed restorations point out an increased risk of tooth loss and the need for more extensive follow-up for the removable dentures. This gives them the patina of being a second-choice therapy. However, they can be less invasive, simpler, and less expensive than implants for a population of older adults who have retained significant portions of their dentition but require restoration of some edentulous spaces. The predictability of the treatment is important information when one is considering the various options for restorations. A systematic literature review was done to identify the survival rates of RDPs for patients with moderately reduced dentition. Methods.—The MEDLINE, EMBASE, BIOSIS, SciSearch, Cochrane, and FIZ Technik Web databases were searched, along with a hand search of relevant dental journals. Nineteen publications were finally selected, including 9 multicenter randomized clinical trials (RCTs), 3 prospective trials, and 7 retrospective trials. Results.—Comparisons were limited by the heterogeneity of the studies in terms of patient selection, study design, and parameters evaluated. Definitions of what constituted a successful outcome differed greatly. Metaanalysis was not possible given the variations between studies. The results were presented in terms of the different types of RDPs. The types considered were cast-metal framework dentures, unilateral attachment prostheses, bilateral attachment prostheses, adhesively bonded attachment RPDs, and double-crown prostheses. With respect to cast-framework RDPs, not wearing them was a significant reason for failure, with failures of 15% to 20% early on. Five-year failure rates ranged from 33% to 50%. A strict follow-up schedule significantly reduced the chance of failure. Some evidence indicates that with this strict follow-up program, cast-framework RDPs may prove satisfactory for over 25 years, with a failure rate of 35% and prosthetic survival rate of 50% for this length of service.
Unilateral attachment prostheses should not be used for Kennedy class II dentitions. Bilateral attachment RDPs have failure rates ranging from 11% to 30% after 5 years. These are comparable to the rates for cast-framework RDPs. Adhesively bonded attachment RDPs are seldom used and have a narrow range of indications. Problems that make this type of RDP risky include potential loosening, although these restorations can often be repaired. Double-crown RDPs have abutment loss rates of 1% to 3% per year, but otherwise they appear to have a good prognosis. The use of complex technologies such as galvanic telescopic RDPs have a higher rate of errors and can carry a higher failure rate. Some evidence indicates that treatment success is linked to extent of pretreatment and follow-up. Prosthesis design appears to be a secondary concern in function. Removable restorations appear to be accompanied by a significantly higher risk for the remaining teeth than a fixed restoration in elderly patients irrespective of the follow-up interval. Higher failure rates and more complications are seen with shortened dental arches, fixed (hybrid) restorations to restore shortened dental arches, and the use of castframework or attachment RDPs. The trends of more tooth loss and prosthetic failure with removable prostheses needs to be substantiated by studies involving larger patient populations and/or longer observations periods. Discussion.—The available evidence on RDPs is not impressive and does not lend itself to comparative analysis. Treatment recommendations cannot be made based on this level of evidence.
Clinical Significance.—RDPs that are preceded by suitable pretreatment and followed by comprehensive care at regular intervals can
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provide patients with a suitable alternative to implant therapy. With such precautions, RDPs may function well for as long as 25 years. However, before recommendations can be made, studies need to provide a higher level of evidence.
Moldovan O, Rudolph H, Luthardt RG: Clinical performance of removable dental prostheses in the moderately reduced dentition: A systematic literature review. Clin Oral Invest 20:1435-1447, 2016 Reprints available from O Moldovan, Dept of Prosthetic Dentistry, Ctr of Dentistry, Ulm Univ, Albert-Einstein-Allee 11, 89081 Ulm, Germany; e-mail: [email protected]
Denture fabrication distortion Background.—Complete dentures are designed to achieve excellent adaptation to mucosa that produces good retention, stability, and support. The fabrication process, however, can introduce some distortion, whether it is by compression molding, pouring a fluid resin, or injection molding—three popular methods of denture processing. A new technique for denture fabrication uses computer-aided design and computer-aided manufacturing (CAD-CAM) techniques involving prepolymerized blocks of polymethyl methacrylate (PMMA), computer software, and 5-axis milling. CADCAM dentures offer the advantage of being completed in as few as 2 appointments rather than the 5 for other methods. In addition, the digitized patient records allow the manufacturing company to quickly prepare an identical replacement prosthesis without the need to make new clinical records should a denture be lost or damaged. In addition to these fabrication advances, laser and contact scanners have improved the ability to measure denture base distortion, so the degree of deformation occurring during fabrication can be determined more accurately than in the past. The denture base adaptation status of pack and press, pour, injection, and CAD-CAM techniques for fabricating dentures was compared to determine which is the most accurate and reproducible method. Methods.—Forty gypsum casts were laser scanned before fabrication, then a master denture was made using the CAD-CAM process, which was used to create a putty mold so that 30 standardized wax festooned dentures could be fabricated. These were divided into three groups of 10 each for processing using the pack and press, pour, or injection techniques. Scan files from 10 casts were sent for fabrication of CAD-CAM test specimens. All the 40 specimens were hydrated for 24 hours before the intaglio surface was scanned. The two scans were then compared using computer software, with measurements taken at 60 locations to assess the fit discrepancies at the apex of the denture border, 6 mm from the denture border, the crest
218
Dental Abstracts
of the ridge, the palate, and the posterior palatal seal area. Accuracy and reproducibility of the casts were then analyzed. Results.—Ideally, none of the casts would show processing deformation and would demonstrate perfect adaptation of the denture base to the cast. All of the methods demonstrated some degree of deformation. The CADCAM technique had the most uniform distribution of adaptation, and the pack and press technique had the least uniform distribution. At the apex of the denture border, no statistically significant difference was noted between CAD-CAM and pack and press specimens. CAD-CAM distortion and pack and press distortion were statistically lower than the distortion seen with the injection and pour methods. At 6 mm from the denture border, CAD-CAM dentures fit differed significantly from all the others. The other methods showed no statistically significant differences in distortion from one another. Pack and press distortion differed significantly from CAD-CAM and pour specimens. Pack and press and injection distortion showed no significant differences. At the palate, a significant difference was noted between the CAD-CAM specimens and the specimens prepared using the other techniques. There were also significant differences between specimens prepared with pack and press and those prepared with injection or pour. Injection specimens differed significantly from pour specimens. At the posterior palatal seal area, CAD-CAM and pack and press distortion showed no significant difference. Significant differences were noted between pack and press and injection and pour specimens and between CAD-CAM and injection and pour specimens. The injection and pour specimens had similar distortion data.
Reprints available from EK Badenoch-Jones, School of Medicine, The Univ of Queensland, Brisbane, Queensland, Australia; e-mail: [email protected]
Removable Prosthodontics Survival of removable dental prostheses Background.—Removable dental prostheses (RDPs) are a well-established option for treating moderately reduced dentition, but the evidence supporting their use is sparse. In addition, comparisons to fixed restorations point out an increased risk of tooth loss and the need for more extensive follow-up for the removable dentures. This gives them the patina of being a second-choice therapy. However, they can be less invasive, simpler, and less expensive than implants for a population of older adults who have retained significant portions of their dentition but require restoration of some edentulous spaces. The predictability of the treatment is important information when one is considering the various options for restorations. A systematic literature review was done to identify the survival rates of RDPs for patients with moderately reduced dentition. Methods.—The MEDLINE, EMBASE, BIOSIS, SciSearch, Cochrane, and FIZ Technik Web databases were searched, along with a hand search of relevant dental journals. Nineteen publications were finally selected, including 9 multicenter randomized clinical trials (RCTs), 3 prospective trials, and 7 retrospective trials. Results.—Comparisons were limited by the heterogeneity of the studies in terms of patient selection, study design, and parameters evaluated. Definitions of what constituted a successful outcome differed greatly. Metaanalysis was not possible given the variations between studies. The results were presented in terms of the different types of RDPs. The types considered were cast-metal framework dentures, unilateral attachment prostheses, bilateral attachment prostheses, adhesively bonded attachment RPDs, and double-crown prostheses. With respect to cast-framework RDPs, not wearing them was a significant reason for failure, with failures of 15% to 20% early on. Five-year failure rates ranged from 33% to 50%. A strict follow-up schedule significantly reduced the chance of failure. Some evidence indicates that with this strict follow-up program, cast-framework RDPs may prove satisfactory for over 25 years, with a failure rate of 35% and prosthetic survival rate of 50% for this length of service.
Unilateral attachment prostheses should not be used for Kennedy class II dentitions. Bilateral attachment RDPs have failure rates ranging from 11% to 30% after 5 years. These are comparable to the rates for cast-framework RDPs. Adhesively bonded attachment RDPs are seldom used and have a narrow range of indications. Problems that make this type of RDP risky include potential loosening, although these restorations can often be repaired. Double-crown RDPs have abutment loss rates of 1% to 3% per year, but otherwise they appear to have a good prognosis. The use of complex technologies such as galvanic telescopic RDPs have a higher rate of errors and can carry a higher failure rate. Some evidence indicates that treatment success is linked to extent of pretreatment and follow-up. Prosthesis design appears to be a secondary concern in function. Removable restorations appear to be accompanied by a significantly higher risk for the remaining teeth than a fixed restoration in elderly patients irrespective of the follow-up interval. Higher failure rates and more complications are seen with shortened dental arches, fixed (hybrid) restorations to restore shortened dental arches, and the use of castframework or attachment RDPs. The trends of more tooth loss and prosthetic failure with removable prostheses needs to be substantiated by studies involving larger patient populations and/or longer observations periods. Discussion.—The available evidence on RDPs is not impressive and does not lend itself to comparative analysis. Treatment recommendations cannot be made based on this level of evidence.
Clinical Significance.—RDPs that are preceded by suitable pretreatment and followed by comprehensive care at regular intervals can
Volume 62
Issue 4
2017
217
provide patients with a suitable alternative to implant therapy. With such precautions, RDPs may function well for as long as 25 years. However, before recommendations can be made, studies need to provide a higher level of evidence.
Moldovan O, Rudolph H, Luthardt RG: Clinical performance of removable dental prostheses in the moderately reduced dentition: A systematic literature review. Clin Oral Invest 20:1435-1447, 2016 Reprints available from O Moldovan, Dept of Prosthetic Dentistry, Ctr of Dentistry, Ulm Univ, Albert-Einstein-Allee 11, 89081 Ulm, Germany; e-mail: [email protected]
Denture fabrication distortion Background.—Complete dentures are designed to achieve excellent adaptation to mucosa that produces good retention, stability, and support. The fabrication process, however, can introduce some distortion, whether it is by compression molding, pouring a fluid resin, or injection molding—three popular methods of denture processing. A new technique for denture fabrication uses computer-aided design and computer-aided manufacturing (CAD-CAM) techniques involving prepolymerized blocks of polymethyl methacrylate (PMMA), computer software, and 5-axis milling. CADCAM dentures offer the advantage of being completed in as few as 2 appointments rather than the 5 for other methods. In addition, the digitized patient records allow the manufacturing company to quickly prepare an identical replacement prosthesis without the need to make new clinical records should a denture be lost or damaged. In addition to these fabrication advances, laser and contact scanners have improved the ability to measure denture base distortion, so the degree of deformation occurring during fabrication can be determined more accurately than in the past. The denture base adaptation status of pack and press, pour, injection, and CAD-CAM techniques for fabricating dentures was compared to determine which is the most accurate and reproducible method. Methods.—Forty gypsum casts were laser scanned before fabrication, then a master denture was made using the CAD-CAM process, which was used to create a putty mold so that 30 standardized wax festooned dentures could be fabricated. These were divided into three groups of 10 each for processing using the pack and press, pour, or injection techniques. Scan files from 10 casts were sent for fabrication of CAD-CAM test specimens. All the 40 specimens were hydrated for 24 hours before the intaglio surface was scanned. The two scans were then compared using computer software, with measurements taken at 60 locations to assess the fit discrepancies at the apex of the denture border, 6 mm from the denture border, the crest
218
Dental Abstracts
of the ridge, the palate, and the posterior palatal seal area. Accuracy and reproducibility of the casts were then analyzed. Results.—Ideally, none of the casts would show processing deformation and would demonstrate perfect adaptation of the denture base to the cast. All of the methods demonstrated some degree of deformation. The CADCAM technique had the most uniform distribution of adaptation, and the pack and press technique had the least uniform distribution. At the apex of the denture border, no statistically significant difference was noted between CAD-CAM and pack and press specimens. CAD-CAM distortion and pack and press distortion were statistically lower than the distortion seen with the injection and pour methods. At 6 mm from the denture border, CAD-CAM dentures fit differed significantly from all the others. The other methods showed no statistically significant differences in distortion from one another. Pack and press distortion differed significantly from CAD-CAM and pour specimens. Pack and press and injection distortion showed no significant differences. At the palate, a significant difference was noted between the CAD-CAM specimens and the specimens prepared using the other techniques. There were also significant differences between specimens prepared with pack and press and those prepared with injection or pour. Injection specimens differed significantly from pour specimens. At the posterior palatal seal area, CAD-CAM and pack and press distortion showed no significant difference. Significant differences were noted between pack and press and injection and pour specimens and between CAD-CAM and injection and pour specimens. The injection and pour specimens had similar distortion data.