The effects of surface machining on heat cured acrylic resin and two soft denture base materials: a scanning electron microscope and confocal microscope evaluation.
BACKGROUND
Rough surfaces promote the adhesion and colonization of denture plaque, therefore it is important to know the character of the surface left by rotary instruments on denture base materials. As a single microscopic technique can introduce artifact, complementary microscope techniques need to be used.


OBJECTIVE
This study investigated the surface characteristics of the machined surfaces of heat-cured acrylic resin, Molloplast B and Novus.


METHODS
Scanning electron microscopy and confocal microscopy were used to investigate surfaces that had been prepared with appropriate clinical rotary instruments. Thirty samples of each material were prepared with steel and tungsten carbide burs, Molloplast stones, and Arbor bands. An analysis of variance, with the Scheffe multiple comparison of means test, was used to compare average surface roughness of the individual surfaces.


RESULTS
The tungsten carbide bur produced a smoother nongrooved surface than the steel bur on acrylic resin. The roughest surfaces were produced on the soft lining materials by the Arbor band and Molloplast stone.


CONCLUSIONS
The confocal microscope is a valuable complementary instrument to scanning electron microscopy and provides surface roughness data by using a noncontact method. Each type of rotary instrument produces its own characteristic surface on denture base materials.
Radford
D R
DR
Department of Prosthetic Dentistry, UMDS, Guys Dental Hospital, University of London, United Kingdom.
Watson
T F
TF
Walter
J D
JD
Challacombe
S J
SJ
D000180:Acrylic Resins / Q000737:chemistry*; D000268:Adhesiveness; D000704:Analysis of Variance; D016477:Artifacts; D001672:Biocompatible Materials / Q000737:chemistry; D001840:Dental Bonding; D003762:Dental Instruments; D003764:Dental Materials / Q000737:chemistry*; D003773:Dental Plaque / Q000382:microbiology; D003819:Denture Bases; D003822:Denture Liners; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D008768:Methylmethacrylates / Q000737:chemistry; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D009943:Organophosphorus Compounds / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D012826:Silicone Elastomers / Q000737:chemistry; D013232:Steel / Q000737:chemistry; D013499:Surface Properties; D017973:Tungsten Compounds / Q000737:chemistry
D000180:Acrylic Resins; D001672:Biocompatible Materials; D003764:Dental Materials; D004129:Dimethylpolysiloxanes; C020964:MDX 4-4210; D008768:Methylmethacrylates; D009943:Organophosphorus Compounds; D011108:Polymers; D012826:Silicone Elastomers; D017973:Tungsten Compounds; C076789:polyphosphazene fluoroelastomer; C002802:tungsten carbide; D013232:Steel; C029883:Trevalon universal