The Effect of Casting Ring Liner Length and Prewetting on the Marginal Adaptation and Dimensional Accuracy of Full Crown Castings.
OBJECTIVE
To evaluate the effect of varying cellulose casting ring liner length and its prewetting on the marginal adaptation and dimensional accuracy of full veneer metal castings.


METHODS
The master die was milled in stainless steel to fabricate the wax pattern. Sixty wax patterns were fabricated with a uniform thickness of 1.5 mm at an occlusal surface and 1 mm axial surface, cervical width at 13.5 mm, and 10 mm cuspal height. The samples were divided into six groups (n= 10). Groups I and II samples had the full-length cellulose prewet and dry ring liner, respectively. The groups III and IV had 2 mm short prewet and dry cellulose ring liner, respectively, whereas groups V and VI were invested in 6 mm short ring liner. The wax patterns were immediately invested in phosphate bonded investment, and casting procedure was completed with nickel-chrome alloy. The castings were cleaned and mean score of measurements at four reference points for marginal adaption, casting height, and cervical width was calculated. The marginal adaption was calculated with Imaje J software, whereas the casting height and cervical width was determined using a digital scale. The data was subjected to one-way analysis of varaince and Tukeypost hocstatistical analysis with Statistical Package for the Social Sciences version 20 software.


RESULTS
The group II had the best marginal adaption with a gap of 63.786 μm followed by group I (65.185 μm), group IV (87.740 μm), and group III (101.455 μm). A large marginal gap was observed in group V at 188.871 μm. Cuspal height was more accurate with group V (10.428 mm), group VI (10.421 mm), and group II (10.488 mm). The cervical width was approximately similar in group I, group III, and group V. Statistically significant difference was observed in Tukeypost hocanalysis between group V and group VI with all the other groups with regards to marginal adaptation.


CONCLUSIONS
The dry cellulose ring liners provided better marginal adaptation in comparison to prewet cellulose ring liners. Accurate cuspal height was obtained with shorter ring liner in comparison to full-length cellulose ring liners.
Department of Prosthodontics, College of Dentistry, King Khalid University, Abha, Saudi Arabia.
Satheesh B
SB
Haralur
Department of Prosthodontics, College of Dentistry, King Khalid University, Abha, Saudi Arabia.
Osama A
OA
Hamdi
Department of Prosthodontics, College of Dentistry, King Khalid University, Abha, Saudi Arabia.
Abdulaziz A
AA
Al-Shahrani
Department of Prosthodontics, College of Dentistry, King Khalid University, Abha, Saudi Arabia.
Sultan
S
Alhasaniah
Casting accuracy; dental casting; investment expansion; marginal adaptation; ring liner