A qualitative analysis to compare the effects of surface machining of conventional denture base resin and two soft liners: a scanning electron microscopic study.
BACKGROUND
The denture base acrylic resins require adjustments for various reasons. During this process there is an alteration in the surface characteristics of the denture base. Rough surfaces promote the bacterial adhesion and plaque accumulation; therefore it is important to know the character of the surface left by instrumentation on denture base materials. This study evaluated the surface characteristics of the machined surfaces of heat-cured acrylic denture base resin, GC supersoft and Permasoft softliners.


METHODS
Thirty 15×15×1.5mm acrylic resin specimens were fabricated with each of three acrylic resins: Lucitone 199 denture base resin (Group I), GC supersoft (Group II) and Permasoft (Group III) softliners. They were further divided into three sub Groups A, B and C, in which Sub Group A was control group that is smooth produced against the glass. Sub Group B was produced by machining with the tungsten carbide bur and Sub group C is machined with the stone bur. Each surface was evaluated by a Scanning electron microscope and data were analyzed by analysis of variance followed by Tukey's HSD test.


RESULTS
Stone bur produced smoother surface (Ra 3.6681μm± 0.254) on Lucitone199 than the tungsten carbide bur (Ra 5.3881μm ± 0.3373). Carbide bur produced a smoother surface on the GC super soft (Ra 1.617097μm ± 0.191767) and Permasoft softliners (Ra 2.237419μm ± 0.354259). Whereas stone bur produced rougher surface on GC supersoft(Ra 2.6μm) and Permasoft (Ra 4.184839μm ± 0.409869) softliners.


CONCLUSIONS
The present study shows each type of rotary instrument produces its own characteristic surface on each type of denture base materials and that care is needed when selecting the most appropriate instrument to adjust denture base materials. These results can have a significant clinical implication. While using Lucitone 199 stone bur can be used for chair side adjustments. Tungsten carbide bur can be used for GC supersoft and Permasoft softliners to achieve smoother surface.
Senior Lecturer, Department of Prosthodontics, MNR Dental College and Hospital , Sangareddy, Telangana, India .
Santoshi V
SV
Kumari
Professor, Department of Prosthodontics, Kamineni Institute of Dental Sciences , Narketpally, Telangana, India .
M
M
Taruna
Professor & Head, Department of Prosthodontics, Kamineni Institute of Dental Sciences , Narketpally, Telangana,India .
B
B
Chittaranjan
Senior Lecturer, Department of Prosthodontics, SVS Dental College and Hospital , Mahabubnagar, Telangana, India .
Sushendhar M
SM
Reddy
Reader, Department of Oral Pathology & Microbiology, MNR Dental College and Hospital , Sangareddy, Telangana, India .
Kranti Kiran E
KK
Reddy
Senior Lecturer, Department of Oral Pathology, Malla Reddy Dental College and Hospital , Jeedimetla, Suraram, Telangana, India .
Ganesh
G
Kulkarni
Acrylic denture base resin; Machining; Soft-liners; Surface roughness