Influence of posts and cores on light transmission through different all-ceramic crowns: spectrophotometric and clinical evaluation.
OBJECTIVE
The influence of different types of posts and cores on light transmission through all-ceramic crowns was assessed by spectrophotometric analysis and clinical evaluation.


METHODS
Three extracted natural teeth were replicated in acrylic resin, with roots prepared to receive standardized posts and cores. Using a silicone impression material as a template, various prosthodontic reconstructions were obtained by combining four types of posts and cores (polished and matte-finished gold alloy, all-ceramic, and ceramized metal alloy) and three types of all-ceramic crowns (IPS-Empress 2 surface-colored, IPS-Empress 2 stratified, and In-Ceram). The spectrophotometric analysis was performed in the dark at 25 degrees C. The teeth were backlit with an incandescent lamp at the color temperature of A illuminant and shielded to avoid spurious light entering the spectrophotometer. The transmitted light was analyzed in terms of luminance at four points of the sample surface (cervical, middle, incisal, and proximal). Twelve measurements were performed for the natural teeth, and 144 were performed for the artificial teeth.


RESULTS
Natural teeth had the highest luminance. Among all-ceramic crowns, surface-colored IPS-Empress 2 had the highest luminance, and stratified IPS-Empress 2 had the lowest. Regarding posts and cores, the luminance was highest with the all ceramic, lower with the ceramized and the polished gold alloy (which had very similar luminance), and lowest with the matte-finished gold alloy. No significant difference among prosthodontic combinations was detected under clinical observation.


CONCLUSIONS
The surface-colored glass ceramic (IPS-Empress 2) was the most translucent crown. At the standard crown thickness used, there were small, significant spectrophotometric, but not clinical, differences among the combinations tested. These findings show no esthetic contraindications for the use of polished gold alloy posts and cores with all-ceramic crowns.
Carossa
S
S
Prosthodontics Department, University of Torino Dental School, Italy.
Lombardo
S
S
Pera
P
P
Corsalini
M
M
Rastello
M L
ML
Preti
P G
PG
D000180:Acrylic Resins; D000537:Aluminum Oxide / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry*; D003116:Color; D003124:Colorimetry; D003442:Crowns; D003624:Darkness; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D004955:Esthetics, Dental; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D008027:Light; D016876:Metal Ceramic Alloys / Q000737:chemistry; D003765:Models, Dental; D010165:Palladium / Q000737:chemistry; D010783:Photometry; D011176:Post and Core Technique / Q000295:instrumentation; D017680:Potassium Compounds / Q000737:chemistry; D013053:Spectrophotometry; D013223:Statistics as Topic; D013499:Surface Properties; D013696:Temperature; D019228:Tooth Crown / Q000033:anatomy & histology; D019231:Tooth Preparation, Prosthodontic; D014172:Transillumination
D000180:Acrylic Resins; D000538:Aluminum Silicates; D006047:Gold Alloys; C075815:IPS-Empress ceramic; D016876:Metal Ceramic Alloys; D017680:Potassium Compounds; D003776:Dental Porcelain; C016447:feldspar; C070870:In-Ceram; D010165:Palladium; C058236:Vitadur N; D000537:Aluminum Oxide