Wear of Enamel Against Polished Zirconia Crowns

A randomized, controlled clinical trial is designed to analyze the wear of enamel by opposing polished monolithic zirconia crowns and by the polished veneer surfaces of metal-ceramic crowns. This single-blind pilot study will involve a total of 30 teeth that require full coverage crowns that oppose natural antagonist teeth.

The objectives of this research are to test the following hypotheses: (1) differences between mean wear of antagonist enamel by polished monolithic zirconia crowns and by the polished veneer surface of metal-ceramic crowns are statistically significant; (2) differences between mean wear of antagonist enamel by opposing polished monolithic zirconia crowns and enamel by opposing enamel are statistically significant; and (3) differences between mean antagonist wear of enamel by opposing polished veneer surfaces of metal-ceramic crowns and enamel by opposing enamel are statistically significant.

To participate in this study a crown will need to be place on one of the back teeth. This generally occurs when the back tooth has a big filling and there is a risk for fracture of the tooth or a root canal has been performed on the tooth. An initial x-ray of the tooth and the surrounding teeth will be done to make sure that there is enough bone supporting the tooth that will be crowned.

A receive local anesthesia will be used in the area where the crown will be made. The tooth area may need to be build-up with a filling material if there is not enough tooth structure remaining. Once this happens, then a high-speed drill will be used to a grind down of the tooth material using to a make smaller size of the original tooth. A small thread will be used to make space between the gums and tooth so an accurate replica of the tooth can be made. A temporary crown will be made to go over the prepared tooth and will cement until the final crown is ready to be cemented.

The extra procedures will be done to measure bite force to see how much force is exerted with the teeth. Other extra procedures include the six month and yearly impressions as well as scanning of your teeth to aid in the measurement of wear.

Participants will be randomly assigned (much like the flip of a coin) to receive either a crown that has metal in it or a crown that is all-ceramic. Both of these materials are considered standard of care in dental practice.

Eligibility Criteria:
Inclusion Criteria:

* Subjects must be over 21 years of age and in good overall health. No contraindications to dental treatment are present
* Subjects must be in good overall good dental health and are at a low caries risk, with no active tooth decay (caries), and no periodontal disease. Periodontal pocket depths on all remaining teeth are not greater than 4 mm
* Subjects must have no existing temporomandibular disorder, (e.g. clicking, popping, pain on opening) or parafunctional habits (e.g. bruxism, clenching)
* Subjects must need a crown on either a first or second premolar or first or second molar in any arch. Abutment teeth must be restorable and have a crown:root ratio of at least 1:1. Abutment teeth must have a full complement of opposing non-restored or minimally restored natural teeth. Minimally restored means the teeth contain no restoration greater than a Class II amalgam restoration. The opposing arch must not have a full coverage restoration or a partial denture. The contralateral tooth and its antagonist are present
* Subjects must exhibit good oral hygiene and compliance with oral hygiene instructions as determined by the amount of plaque present on tooth surfaces
* Subjects must exhibit a normal flow of saliva. Subjects with any medical pathologies that limit salivary flow volume or who require a chronic intake of medications that minimize flow of saliva will be excluded from the study
* Subjects must be willing to pay $500 for the clinic incidentals and they must be compliant with yearly appointments

Exclusion Criteria:

* anything that does not meet inclusion criteria