Track topics on Twitter Track topics that are important to you
1. To characterize the microstructure (fracture toughness, particle size of ceramic, and inter-particle spacing) of three ceramic materials
2. To test the hypothesis that lower fracture toughness of glass and/or crystal phase in ceramics reduce wear damage of enamel.
3. To test the hypothesis that smaller sized crystals reduce wear damage of enamel.
4. To test the hypothesis that larger inter-particle spacing reduces wear damage of enamel.
5. To test the hypothesis that equivalent wear patterns exist in all directions between enamel versus enamel and ceramic versus enamel.
6. To test the hypothesis that bite force does not correlate with wear rates.
7. To test the hypothesis that salivary flow does not correlate with wear rates.
8. To test the hypothesis that a greater amount of wear is not associated with a loss in vertical dimension of occlusion.
9. To test the hypothesis that a greater amount of wear does not correlate with secondary cementum deposition as part of the passive eruption process.
10. To test the hypothesis that maximum wear occurs early and wear rates level off within the first two years.
11. To test the hypothesis that in vitro wear analysis does not correlate with in vivo wear measurements
1. Subjects must be over 18 years of age with good overall health. No contraindications to dental treatment must be present.
2. Subjects must have overall good dental health with no active tooth decay (caries) present and no periodontal disease. Pocket depth on all remaining teeth must not be more than 4 mm.
3. Subjects must have no existing temporomandibular disorder, (e.g. clicking, popping, pain on opening) or parafunctional habits (e.g. bruxism, clenching)
4. Subjects must need a crown on either a second premolar, first molar or second molar on any arch. Abutment teeth must be restorable and have a crown root ratio of at least 1:1. Abutment teeth must have a complement of opposing non-restored or minimally restored natural teeth. Minimally restored means nothing beyond a Class II amalgam restoration. Opposing arch cannot be a full coverage restoration or a partial denture. Contralateral tooth must be preferably present.
5. Subjects must exhibit good oral hygiene and compliance.
6. Subjects must not have any existing condition that could limit the flow of saliva; e.g. saliva flow must be of normal quantity.
Baseline data will be collected and will consist of:
1. General medical history and physical examination
2. Primary casts taken with polyvinylsiloxane impression material
3. Bite force measurement in Newtons using a gnathodynamometer
4. Pocket depths of abutment teeth must be recorded
5. Periapical radiographs of abutment teeth. Radiographs will be taken at the exact position with the use of the longitudinal radiographic analysis (LRA) technique.
6. Vertical dimension measured from the nasion to the lowest point on the chin
7. A saliva sample will be collected to ascertain quality (viscosity) and quantity. The parameters for analysis will be salivary pH, buffer capacity, secretion (ml/min), protein (mg/ml), phosphate (mmol/l), Ca (mval/l), Na (mval/l), K (mval/l).
A total of 36 teeth will be randomly assigned to receive either a metal-ceramic (D’Sign) or an all-ceramic crown (IPS Empress2, Eris EXC). Randomization will be done through a random number table. Teeth will be prepared by two operators: Dr. Josephine Esquivel-Upshaw and Dr. William Rose both from the General Dentistry department. Provisional restorations will be made from Integrity (Dentsply, USA) and final impressions will be made with a polyvinylsiloxane material using the two-stage technique. Master casts will be mounted in centric relation.
A single unit crown will be made from either two types of an all-ceramic material or a metal-ceramic material and cemented with a dual cure resin cement. Adjustments will be made with a high-speed handpiece and a fine diamond bur. Prior to cementation, all adjusted surfaces must be polished or glazed. Occlusal surface thickness of the crowns will be measured at baseline.
Baseline examination will be performed one week after cementation to ensure that the patient is comfortable with the crown and no further adjustments are needed. A polyvinylsiloxane impression will be made of the maxillary and mandibular arches to record the cemented crown and its antagonist arch.
The post-cementation casts will be poured with a Type IV gypsum product to enable proper scanning. A 3D Laserscanner will be used to scan in the x, y and z planes of tooth/teeth casts made from natural teeth. The vertical dimension will be recorded as well as periapical radiographs taken of the abutment teeth.
The subjects will be asked to return after six months of cementation. Polyvinylsiloxane impressions will once again be made of maxillary and mandibular arches and poured with Type IV stone. The antagonist teeth and the crown will be scanned using the 3D Laserscanner. Superimposition of baseline image and the six-month image will be performed and the amount of wear in three dimensions calculated mathematically. Vertical dimension of occlusion will also be determined by measurement of nasion to the lowest point on the chin and periapical radiographs taken of the restored teeth using the LRA technique. This procedure will be repeated every year for the next four years.
The amount of wear in microns will be determined for the x, y and z axes. Data will be subjected to a one-way ANOVA (α = 0.05 ) to determine any significant difference in wear of natural antagonist teeth and the ceramic crowns between baseline and yearly 3D images and also differences in wear between the yearly 3D images. Occlusal thickness of restorations will be determined based on the amount of wear calculated. Any presence of cracks or fractures will be recorded. Correlation of the amount of wear and any changes in vertical dimension and root cementum length will also be determined by comparison of nasion-chin height at different intervals.
Allocation: Randomized, Control: Active Control, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Treatment
ceramic and PFM crowns
University of Texas Health Science Center at San Antonio
Active, not recruiting
The University of Texas Health Science Center at San Antonio
Published on BioPortfolio: 2014-07-23T21:47:45-0400
The objectives of this study are to characterize the clinical performance and wear mechanisms of all-ceramic posterior crowns. The wear rate of all-ceramic crowns and opposing enamel in s...
This investigation will be a clinical trial to study the performance of a newly developed high strength ceramic material for crowns. The ceramic has been approved by the FDA for patient tr...
This study aims determine the wear rates of enamel versus enamel and enamel versus ceramic in human beings in relation to the microstructure of the ceramic material. Specific aims of the ...
The aim of the study is to evaluate the complication rate of 2 types of all-ceramic crowns in patients with or without bruxism.
The purpose of this study is to investigate the use of an all-ceramic dental crown material to restore the abutment teeth of partially-edentulous patients who need removable partial dentur...
This manuscript summarises the reasons behind choosing indirect restorations in the treatment of tooth wear. The purpose of this article is to discuss the use of crowns as a restorative treatment opti...
The aim of this study was to assess the clinical outcomes and patient satisfaction with monolithic zirconia crowns in patients with severe tooth wear (≥1/3 of the tooth crown) in the aesthetic zone.
Marginal gap (MG) was the most important factor to evaluate the success of crowns. The study was to assess the MG of lithium disilicate glass ceramic crowns with spectral domain optical coherence tomo...
To evaluate in vitro the influence of firing on marginal and internal fit of all-ceramic milled and pressed lithium-disilicate crowns.
To evaluate the fracture resistance and failure mode of three different all-ceramic crowns; CEREC Bloc, IPS e.Max Press and Cercon in a simulated clinical situation.
A type of porcelain used in dental restorations, either jacket crowns or inlays, artificial teeth, or metal-ceramic crowns. It is essentially a mixture of particles of feldspar and quartz, the feldspar melting first and providing a glass matrix for the quartz. Dental porcelain is produced by mixing ceramic powder (a mixture of quartz, kaolin, pigments, opacifiers, a suitable flux, and other substances) with distilled water. (From Jablonski's Dictionary of Dentistry, 1992)
Loss of the tooth substance by chemical or mechanical processes
Occlusal wear of the surfaces of restorations and surface wear of dentures.
A prosthetic restoration that reproduces the entire surface anatomy of the visible natural crown of a tooth. It may be partial (covering three or more surfaces of a tooth) or complete (covering all surfaces). It is made of gold or other metal, porcelain, or resin.
An appliance used as an artificial or prosthetic replacement for missing teeth and adjacent tissues. It does not include CROWNS; DENTAL ABUTMENTS; nor TOOTH, ARTIFICIAL.
Osteoporosis is a disease in which the bones become extremely porous, are subject to fracture, and heal slowly, occurring especially in women following menopause and often leading to curvature of the spine from vertebral collapse. Follow and track&n...
Dentistry is the study, management and treatment of diseases and conditions affecting the mouth, jaw, teeth and their supporting tissues (Oxford Medical Dictionary) The work of a dentist ranges from regular patient check-up to orthodontics and surgery....