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Fit of clasp assemblies for removable partial dentures
ECC over the 6 to 24 months just after comprehensive treatment was determined, as well as the impact of attending an immediate postoperative follow-up appointment on the likelihood of relapse. Methods.—One hundred ninety-three children younger than 61 months at the time of treatment were evaluated. One hundred sixty-seven attended at least one 6-month recall appointment or came for an emergency visit within 6 to 24 months of treatment. Results.—The children ranged in age from 19 to 60 months (mean, 41 months). Thirty-nine percent had returned for their immediate 2-week follow-up appointment, and 87% were seen for at least one 6-month recall appointment. New lesions developed within 2 years in 103 children (53.4% of the entire sample). Of these, 46.6% had lesions limited to the primary dentition, 12% had lesions limited to the permanent teeth, and 5% had new lesions in both. Children who had attended their 2-week follow-up appointment were less likely to have new caries lesions than those who had not attended, but the relationship was not statistically significant. A trend was detected with regard to new caries in primary dentition, with children who attended their follow-up appointment less likely to have new carious lesions in their primary teeth. This trend did not reach statistical significance.
Discussion.—Over half the children did not attend their immediate postoperative appointment after aggressive treatment for ECC. Eighty-seven percent did attend at least 1 recall appointment in the first 2 years after treatment. New caries lesions developed in 53% of the children within 2 years. Those who attended their follow-up appointment were less likely to develop new lesions than those who did not keep the follow-up appointment, but the difference was not statistically significant.
Clinical Significance.—While general anesthesia may be the only route possible to manage urgent problems in the very young, the results of this study underscore the need for follow-up and education of both patient and parent, without which the same behavior responsible for the initial problem will recur.
Foster T, Perinpanayagam H, Pfaffenbach A, et al: Recurrence of early childhood caries after comprehensive treatment with general anesthesia and follow-up. J Dent Child 73:25-30, 2006 Reprints available from H Perinpanayagam; e-mail: [email protected]
Prosthodontics Fit of clasp assemblies for removable partial dentures Background.—Clasp assemblies are a key component of removable partial dental prostheses (RDPs) and usually include the use of a rest. Rest seats are designed to accept the cast rest portion of the RDP framework so that masticatory forces are directed in a particular way. If the rest does not contact the right area, it is believed that the correct outcome will be compromised. The components of
62 Dental Abstracts
the RDP clasp assembly that actually contact the abutment tooth clinically were evaluated. Methods.—The fit of new and existing frameworks with a minimum of 1 conventional prepared occlusal rest was assessed. Vinyl polysiloxane was applied to record the spacing between the bottom of each rest in 50 clasp as-
Fig 4.—Left, Diagram of variation of fit of bevel versus butt joint relationships. Right, Diagram demonstrating potential clinical relationship between rest and rest seat. (Reprinted from Stern et al5 with permission from Elsevier, Inc.) (Reprinted from Dunham D, Brudvik JS, Morris WJ, et al: A clinical investigation of the fit of removable partial dental prosthesis clasp assemblies. J Prosthet Dent 95:323-326, 2006. Copyright 2006, with permission from The Editorial Council of the Journal of Prosthetic Dentistry.)
semblies and the corresponding rest seat. A dial caliper measured the fit of each rest, recording the thickness between the rest and the bottom of the rest seat. Differences in fit between tooth-tissue supported and tooth-supported designs were also analyzed statistically. Results.—The range for the space between the rest and the prepared rest seat was 0 to 828 µm and the average was 193 µm. The average space was 136 µm for the 20 tooth-tissue frameworks and 230 µm for the 30 toothsupported frameworks. Fit did not differ significantly between the 2 types of frameworks. In 24% of the rests, the rest was in contact with the rest seat. In 7%, the occlusal rests contacted only on the periphery, with notable space under their central portions (Fig 4). Discussion.—No clinical evidence supports the practice of having the rest direct occlusal forces in a particular manner, with its effectiveness unproved. The results of this study indicate that it may be time to modify the way we achieve support and resistance with RDP frameworks. Specifically, a more conservative approach to rest design and preparation of the abutment teeth may be in order. If 2 broad contacts or 3 points of suprabulge contact are achieved, the framework may be adequately supported (Fig 5). The use of the suprabulge tooth surface can effec-
Fig 5.—Diagram illustrating concept of suing suprabulge “rest projections” to achieve support. (Reprinted from Brudvik6 with permission from Quintessence Publishing Co, Inc). (Reprinted from Dunham D, Brudvik JS, Morris WJ, et al: A clinical investigation of the fit of removable partial dental prosthesis clasp assemblies. J Prosthet Dent 95:323-326, 2006. Copyright 2006, with permission from The Editorial Council of the Journal of Prosthetic Dentistry.)
tively provide the accepted over-180–degree encirclement. The most effective areas to target for support appear to be the suprabulge areas near the occlusal surface, for example, the marginal ridge.
Clinical Significance.—Echoing the mantra that things are not always as they obviously seem to be, many of the claims about requirements for occlusal rest design in removable partial denture prostheses and the mechanical results anticipated are disputed here. More conservative mouth preparation and simpler design are the result.
Dunham D, Brudvik JS, Morris WJ, et al: A clinical investigation of the fit of removable partial dental prosthesis clasp assemblies. J Prosthet Dent 95:323-326, 2006 Reprints available from SM Cameron, 1533 Clary Cut Rd, Appling, GA 30802; fax: 706-787-7528; e-mail: [email protected]
Volume 52 • Issue 1 • 2007 63
Discussion.—Over half the children did not attend their immediate postoperative appointment after aggressive treatment for ECC. Eighty-seven percent did attend at least 1 recall appointment in the first 2 years after treatment. New caries lesions developed in 53% of the children within 2 years. Those who attended their follow-up appointment were less likely to develop new lesions than those who did not keep the follow-up appointment, but the difference was not statistically significant.
Clinical Significance.—While general anesthesia may be the only route possible to manage urgent problems in the very young, the results of this study underscore the need for follow-up and education of both patient and parent, without which the same behavior responsible for the initial problem will recur.
Foster T, Perinpanayagam H, Pfaffenbach A, et al: Recurrence of early childhood caries after comprehensive treatment with general anesthesia and follow-up. J Dent Child 73:25-30, 2006 Reprints available from H Perinpanayagam; e-mail: [email protected]
Prosthodontics Fit of clasp assemblies for removable partial dentures Background.—Clasp assemblies are a key component of removable partial dental prostheses (RDPs) and usually include the use of a rest. Rest seats are designed to accept the cast rest portion of the RDP framework so that masticatory forces are directed in a particular way. If the rest does not contact the right area, it is believed that the correct outcome will be compromised. The components of
62 Dental Abstracts
the RDP clasp assembly that actually contact the abutment tooth clinically were evaluated. Methods.—The fit of new and existing frameworks with a minimum of 1 conventional prepared occlusal rest was assessed. Vinyl polysiloxane was applied to record the spacing between the bottom of each rest in 50 clasp as-
Fig 4.—Left, Diagram of variation of fit of bevel versus butt joint relationships. Right, Diagram demonstrating potential clinical relationship between rest and rest seat. (Reprinted from Stern et al5 with permission from Elsevier, Inc.) (Reprinted from Dunham D, Brudvik JS, Morris WJ, et al: A clinical investigation of the fit of removable partial dental prosthesis clasp assemblies. J Prosthet Dent 95:323-326, 2006. Copyright 2006, with permission from The Editorial Council of the Journal of Prosthetic Dentistry.)
semblies and the corresponding rest seat. A dial caliper measured the fit of each rest, recording the thickness between the rest and the bottom of the rest seat. Differences in fit between tooth-tissue supported and tooth-supported designs were also analyzed statistically. Results.—The range for the space between the rest and the prepared rest seat was 0 to 828 µm and the average was 193 µm. The average space was 136 µm for the 20 tooth-tissue frameworks and 230 µm for the 30 toothsupported frameworks. Fit did not differ significantly between the 2 types of frameworks. In 24% of the rests, the rest was in contact with the rest seat. In 7%, the occlusal rests contacted only on the periphery, with notable space under their central portions (Fig 4). Discussion.—No clinical evidence supports the practice of having the rest direct occlusal forces in a particular manner, with its effectiveness unproved. The results of this study indicate that it may be time to modify the way we achieve support and resistance with RDP frameworks. Specifically, a more conservative approach to rest design and preparation of the abutment teeth may be in order. If 2 broad contacts or 3 points of suprabulge contact are achieved, the framework may be adequately supported (Fig 5). The use of the suprabulge tooth surface can effec-
Fig 5.—Diagram illustrating concept of suing suprabulge “rest projections” to achieve support. (Reprinted from Brudvik6 with permission from Quintessence Publishing Co, Inc). (Reprinted from Dunham D, Brudvik JS, Morris WJ, et al: A clinical investigation of the fit of removable partial dental prosthesis clasp assemblies. J Prosthet Dent 95:323-326, 2006. Copyright 2006, with permission from The Editorial Council of the Journal of Prosthetic Dentistry.)
tively provide the accepted over-180–degree encirclement. The most effective areas to target for support appear to be the suprabulge areas near the occlusal surface, for example, the marginal ridge.
Clinical Significance.—Echoing the mantra that things are not always as they obviously seem to be, many of the claims about requirements for occlusal rest design in removable partial denture prostheses and the mechanical results anticipated are disputed here. More conservative mouth preparation and simpler design are the result.
Dunham D, Brudvik JS, Morris WJ, et al: A clinical investigation of the fit of removable partial dental prosthesis clasp assemblies. J Prosthet Dent 95:323-326, 2006 Reprints available from SM Cameron, 1533 Clary Cut Rd, Appling, GA 30802; fax: 706-787-7528; e-mail: [email protected]
Volume 52 • Issue 1 • 2007 63