- Email: [email protected]
Current dental implant occlusion knowledge
Methods.—Eighteen edentulous patients participated in a crossover clinical trial. All had mandibular denture problems and received 2 mandibular implants and new mandibular and maxillary dentures. Initially, no attachment system was used for the mandibular denture, but after 3 months, 1 of the 3 systems was fitted to the denture. This attachment was changed 3 months later. Patients completed a questionnaire at baseline to determine their assessment of their old denture, after 3 months with no attachment system for the new denture, and again after 3 months with each of the attachment systems. A visual analogue scale was used to gauge patients’ overall assessment of their dentures. Patient preferences were also determined after all treatment had been experienced. The maximum bite forces were obtained from a previous study of the same population, with comparisons then made between these values and the patient-derived scores.
though no marked subjective improvement was recorded for any of the attachment systems. The visual analogue scale scores indicated that patients felt there was a major improvement in overall denture satisfaction with the new denture and an attachment system, favoring the bar-clip and ball-socket attachments more than magnets. Ten patients preferred the bar-clip attachment, 7 the ball-socket attachment, and 1 the magnet attachment. No statistically significant correlation was noted between maximum bite force and any of the scale measures obtained.
Results.—Fewer complaints were expressed about the new maxillary dentures used with the mandibular denture without attachments than about the old dentures. No difference in maxillary denture function was found between the dentures with and without any attachment system. The mandibular dentures without any attachment system were rated as better than the old dentures. No statistically significant difference in patient complaints was found among the 3 types of attachments. General denture complaints were most common with the old dentures. The best scores on the general complaints scale were achieved with the bar-clip and ball-socket attachment systems. Magnet systems did not improve patient satisfaction significantly. Old dentures were noted to produce complaints in the areas of physiognomy, neutral space, and esthetics, with better scores for the new conventional dentures, al-
Clinical Significance.—Patients strongly preferred bar-clip and ball-socket retention to magnets. Surprisingly, biting force did not necessarily correlate with patient satisfaction.
Discussion.—A strong preference was noted for the bar-clip and ball-socket attachments rather than the magnet attachments for these implant-supported mandibular overdentures. Baseline factors did not predict patient preferences. Therefore, patients who had a higher maximum bite force were not always more satisfied.
Cune M, van Kampen F, van der Bilt A, et al: Patient satisfaction and preference with magnet, bar-clip, and ball-socket retained mandibular implant overdentures: A cross-over clinical trial. Int J Prosthodont 18:99-105, 2005 Reprints available from MS Cune, Univ Medical Ctr, PO Box 85.060, Utrecht 3508 AB, The Netherlands; fax: + 31-30-2535537; e-mail: [email protected]
Current dental implant occlusion knowledge Background.—Determining the appropriate occlusion and understanding its role in the biological and mechanical stability of implant therapy have been controversial issues. An assessment of what we know and what we need to know was carried out.
364 Dental Abstracts
Occlusion.—Occlusion and the loading that occurs as a result play a role in the longevity of a restoration but have minimal influence on the loss of an implant. An axial load seldom occurs relative to the implant long axis during occlusal function. Function occurs in various areas of the
prosthesis and involves complex bending moments within the components of the implant and the surrounding bone. The design of a prosthesis must consider the contribution of the load induced by a food bolus and the areas that receive the load relative to the implant connection’s central axis. The bending moment developed within the prosthesis and implant assembly can far exceed the measured bite forces on the prosthesis when no food is present. Food as a bolus changes the magnitude and direction of the masticatory load and must be considered in making decisions concerning occlusion. Biological Factors.—The 1 study addressing the role of implant loss in supra-occlusion was performed in a primate model and must be interpreted cautiously. Few implants were lost and significant lateral forces on the implants were not measured. The conclusion was that failure resulted from the combination of excessive inflammation and overload. Further studies have indicated that significant loads are transferred to bone in implant situations. The implant interface is maintained by a continuous process of remodeling at the interface that permits bone to withstand a number of errors occurring in clinical procedures while creating a biological interface that supports clinical loads for long periods. As implant surface technology has advanced, the survival of implants in high-risk sites also has improved, yielding a reasonable predictability of more than 90% survival. Surface roughness is a significant factor in the interfacial strength of an implant after healing. Both optimal surface topography and macroscopic architecture are important and relevant in determinations of occlusion. With natural dentition, occlusal loading produces an inherent feedback loop wherein proprioceptive fibers of the periodontal ligament protect the radicular dentin, cementum, periodontal ligament and alveolar bone from excessive trauma while chewing. This protective function does not exist with the implant interface. The presence of an adaptive response, termed osseoperception, has developed in the region surrounding an implant prosthesis, involving a relative increase in sensation and neural capacity. This development suggests that bone can compensate for the loss of the periodontal ligament. Shear strains on the interface are controlled by the surface mechanical “bonding” of bone to the implant surface through macroscopic and microscopic architecture, such as roughness. Thus, the im-
plant interface can increase its local external stiffness during load transfer, providing 1 method of measuring implant integration. Mechanical Factors.—Screw loosening is no longer a major complication of implant therapy, but the durability and lifespan of the prosthesis are of concern. Maintenance is linked to occlusal loading for implantsupported prostheses. The patient should be informed that mechanical complications can occur with implants and include wear and veneer fractures. Patients must also realize that the prosthesis will need to be replaced or repaired periodically. With this in mind, the clinician must assess any implant system to determine the maintenance outcomes of the implants, the abutments, and the prosthesis. Discussion.—With a better understanding of occlusal loading and its influence on outcome for implant restorations will come optimal patient care. Knowing that there are multiple mechanical and biological factors that influence the longevity of implant-supported restorations is helpful in making good treatment decisions. Failures that occur can be instructive. Ongoing investigations of various occlusal concepts will aid in treatment planning and restorative designs.
Clinical Significance.—Most of what we know about implant occlusion we know from our experience with dentate occlusion. Implants are not teeth. Much study is still needed to determine how these principles apply to implants and what, if any, changes are needed.
Stanford CM: Issues and considerations in dental implant occlusion: What do we know, and what do we need to find out? Calif Dent Assoc J 33:329-336, 2005 Reprints available from CM Stanford, Dows Inst for Dental Research and Dept of Prosthodontics, 447 Dental Science Bldg North, Univ of Iowa, Iowa City, Iowa 52242
Volume 50 • Issue 6 • 2005 365
though no marked subjective improvement was recorded for any of the attachment systems. The visual analogue scale scores indicated that patients felt there was a major improvement in overall denture satisfaction with the new denture and an attachment system, favoring the bar-clip and ball-socket attachments more than magnets. Ten patients preferred the bar-clip attachment, 7 the ball-socket attachment, and 1 the magnet attachment. No statistically significant correlation was noted between maximum bite force and any of the scale measures obtained.
Results.—Fewer complaints were expressed about the new maxillary dentures used with the mandibular denture without attachments than about the old dentures. No difference in maxillary denture function was found between the dentures with and without any attachment system. The mandibular dentures without any attachment system were rated as better than the old dentures. No statistically significant difference in patient complaints was found among the 3 types of attachments. General denture complaints were most common with the old dentures. The best scores on the general complaints scale were achieved with the bar-clip and ball-socket attachment systems. Magnet systems did not improve patient satisfaction significantly. Old dentures were noted to produce complaints in the areas of physiognomy, neutral space, and esthetics, with better scores for the new conventional dentures, al-
Clinical Significance.—Patients strongly preferred bar-clip and ball-socket retention to magnets. Surprisingly, biting force did not necessarily correlate with patient satisfaction.
Discussion.—A strong preference was noted for the bar-clip and ball-socket attachments rather than the magnet attachments for these implant-supported mandibular overdentures. Baseline factors did not predict patient preferences. Therefore, patients who had a higher maximum bite force were not always more satisfied.
Cune M, van Kampen F, van der Bilt A, et al: Patient satisfaction and preference with magnet, bar-clip, and ball-socket retained mandibular implant overdentures: A cross-over clinical trial. Int J Prosthodont 18:99-105, 2005 Reprints available from MS Cune, Univ Medical Ctr, PO Box 85.060, Utrecht 3508 AB, The Netherlands; fax: + 31-30-2535537; e-mail: [email protected]
Current dental implant occlusion knowledge Background.—Determining the appropriate occlusion and understanding its role in the biological and mechanical stability of implant therapy have been controversial issues. An assessment of what we know and what we need to know was carried out.
364 Dental Abstracts
Occlusion.—Occlusion and the loading that occurs as a result play a role in the longevity of a restoration but have minimal influence on the loss of an implant. An axial load seldom occurs relative to the implant long axis during occlusal function. Function occurs in various areas of the
prosthesis and involves complex bending moments within the components of the implant and the surrounding bone. The design of a prosthesis must consider the contribution of the load induced by a food bolus and the areas that receive the load relative to the implant connection’s central axis. The bending moment developed within the prosthesis and implant assembly can far exceed the measured bite forces on the prosthesis when no food is present. Food as a bolus changes the magnitude and direction of the masticatory load and must be considered in making decisions concerning occlusion. Biological Factors.—The 1 study addressing the role of implant loss in supra-occlusion was performed in a primate model and must be interpreted cautiously. Few implants were lost and significant lateral forces on the implants were not measured. The conclusion was that failure resulted from the combination of excessive inflammation and overload. Further studies have indicated that significant loads are transferred to bone in implant situations. The implant interface is maintained by a continuous process of remodeling at the interface that permits bone to withstand a number of errors occurring in clinical procedures while creating a biological interface that supports clinical loads for long periods. As implant surface technology has advanced, the survival of implants in high-risk sites also has improved, yielding a reasonable predictability of more than 90% survival. Surface roughness is a significant factor in the interfacial strength of an implant after healing. Both optimal surface topography and macroscopic architecture are important and relevant in determinations of occlusion. With natural dentition, occlusal loading produces an inherent feedback loop wherein proprioceptive fibers of the periodontal ligament protect the radicular dentin, cementum, periodontal ligament and alveolar bone from excessive trauma while chewing. This protective function does not exist with the implant interface. The presence of an adaptive response, termed osseoperception, has developed in the region surrounding an implant prosthesis, involving a relative increase in sensation and neural capacity. This development suggests that bone can compensate for the loss of the periodontal ligament. Shear strains on the interface are controlled by the surface mechanical “bonding” of bone to the implant surface through macroscopic and microscopic architecture, such as roughness. Thus, the im-
plant interface can increase its local external stiffness during load transfer, providing 1 method of measuring implant integration. Mechanical Factors.—Screw loosening is no longer a major complication of implant therapy, but the durability and lifespan of the prosthesis are of concern. Maintenance is linked to occlusal loading for implantsupported prostheses. The patient should be informed that mechanical complications can occur with implants and include wear and veneer fractures. Patients must also realize that the prosthesis will need to be replaced or repaired periodically. With this in mind, the clinician must assess any implant system to determine the maintenance outcomes of the implants, the abutments, and the prosthesis. Discussion.—With a better understanding of occlusal loading and its influence on outcome for implant restorations will come optimal patient care. Knowing that there are multiple mechanical and biological factors that influence the longevity of implant-supported restorations is helpful in making good treatment decisions. Failures that occur can be instructive. Ongoing investigations of various occlusal concepts will aid in treatment planning and restorative designs.
Clinical Significance.—Most of what we know about implant occlusion we know from our experience with dentate occlusion. Implants are not teeth. Much study is still needed to determine how these principles apply to implants and what, if any, changes are needed.
Stanford CM: Issues and considerations in dental implant occlusion: What do we know, and what do we need to find out? Calif Dent Assoc J 33:329-336, 2005 Reprints available from CM Stanford, Dows Inst for Dental Research and Dept of Prosthodontics, 447 Dental Science Bldg North, Univ of Iowa, Iowa City, Iowa 52242
Volume 50 • Issue 6 • 2005 365