In vivo wear of enamel by a lithia disilicate-based core ceramic used for posterior fixed partial dentures: first-year results.
OBJECTIVE
This study aimed (1) to test the hypothesis that no significant relationship exists between the magnitude of occlusal clenching force and wear rates of enamel opposing a new core ceramic (e.max Press, Ivoclar Vivadent) used in posterior fixed partial dentures (FPDs); and (2) to test the hypothesis that mean annual enamel wear by an experimental core ceramic is comparable to the mean annual enamel wear by enamel of 38 microm.


METHODS
Baseline data were obtained for patients in addition to preliminary impressions of maxillary and mandibular teeth. Thirty ceramic FPDs were processed from a new core ceramic (e.max Press) that was hot pressed and glazed. Patients were recalled 1 year after cementation and evaluated using clinical criteria that included wear assessment of opposing teeth. Impressions were made of the opposing teeth with polyvinylsiloxane impression material and photographs were taken of intraoral occlusal contacts marked with articulating ribbon. Baseline casts and casts made at each recall exam of opposing dentitions were scanned using a 3-dimensional laser scanner (Laserscan 3D, Willytec) and evaluated for wear. A total of 21 occlusal surfaces were analyzed for the presence of wear.


RESULTS
Statistical analysis using a linear and quadratic model revealed no significant relationship between occlusal forces and wear rate assuming either a linear model (R2 = 0.018) or a quadratic model (R2 = 0.023). The maximum annual wear of enamel by the glazed core ceramic (e.max Press) was 88.3 microm, which is significantly greater than the annual enamel-by-enamel wear of 38 microm (P < .0001).


CONCLUSIONS
Further analysis with a larger sample size is needed to determine the relationship between occlusal clenching force and wear rate and the influence of other factors that cause increased wear of enamel by opposing ceramic restorations.
Esquivel-Upshaw
Josephine F
JF
Department of Prosthodontics, University of Florida, PO Box 100435, Gainesville, Florida 32610, USA. jesquivel@dental.ufl.edu
Young
Henry
H
Jones
Jack
J
Yang
Mark
M
Anusavice
Kenneth J
KJ
D000328:Adult; D001641:Bicuspid / Q000473:pathology; D001732:Bite Force; D002484:Cementation; D003743:Dental Enamel / Q000473:pathology*; D003760:Dental Impression Materials / Q000737:chemistry; D003776:Dental Porcelain / Q000737:chemistry*; D003779:Denture Design; D003830:Denture, Partial, Fixed; D005260:Female; D005500:Follow-Up Studies; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007834:Lasers; D008297:Male; D008875:Middle Aged; D008963:Molar / Q000473:pathology; D011145:Polyvinyls / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012833:Siloxanes / Q000737:chemistry; D013499:Surface Properties; D019217:Tooth Attrition / Q000209:etiology* / Q000473:pathology
D003760:Dental Impression Materials; D005899:Glass Ionomer Cements; D011145:Polyvinyls; D019279:Resin Cements; D012833:Siloxanes; C493120:lithia disilicate; C034183:vinyl polysiloxane; D003776:Dental Porcelain