The aim of this study is to evaluate the wear produced in the short and medium term by monolithic zirconia, metal-ceramic and lithium disilicate restorations on the antagonist natural enamel in patients with fixed prostheses, assessing the factors that may influence this wear.

The investigators will also analyse whether the wear of the tooth antagonistic to the different restorations differs significantly with respect to the wear of the natural tooth (control group). The null hypothesis is that there are no significant differences.

The study will be carried out on patients who will be candidates for treatment with full coverage restorations on teeth (single crowns). These crowns will be made of one of the following materials: monolithic zirconia, lithium disilicate or metal-ceramic, which will be cemented according to the guidelines defined in the scientific literature.

Inclusion criteria will be: patients in need of full coverage crowns on a first or second premolar or first or second molar in any arch, over 18 years of age, no contraindications for dental treatment, good oral hygiene, no periodontal disease or treated periodontal disease, absence of temporomandibular disorder and/or untreated habits or parafunctions.

The aim of this study is to evaluate the wear produced in the short and medium term by monolithic zirconia, metal-ceramic and lithium disilicate restorations on the antagonist tooth in patients with fixed prostheses, assessing the factors that may influence this wear.

The investigators will also analyse whether the wear of the tooth antagonistic to the different restorations differs significantly with respect to the wear of the natural tooth (control group). The null hypothesis is that there are no significant differences.

Once the treatment has been completed, the patient must attend routine check-ups in which a complete intraoral exploration, a scan and data collection for both arches will be carried out in order to analyse the following variables: wear of the antagonist tooth to ceramic restorations, wear of the restoration itself and physiological wear of the natural tooth. The same intervention will be carried out for the duration of the project, at the following time intervals: baseline (day of cementation of the restoration), 1 month, 6 months and annually. If an intraoral scanner is not available, silicone impressions will be made, which will be cast with plaster and scanned extraorally.

The investigators will work with a sample "n" of 75 patients, collected over the next two years. Depending on the material used to fabricate the restoration, 4 different groups will be differentiated: monolithic zirconia (group 1), metal-ceramic (group 2), lithium disilicate (group 3) and natural tooth (control group). The patients will be randomly distributed into the different groups using the online randomisation software www.alazarinfo.es.

INCLUSION CRITERIA:

• Patients in need of single tooth restorations on posterior teeth.
• Age range: between 18 years of age.
• No contraindications for dental treatment.
• Good oral hygiene.
• No periodontal disease or treated periodontal disease.
• Absence of temporomandibular disorder and/or untreated habits or parafunctions.

Inclusion criteria for abutment teeth:

1. Posterior tooth requiring placement of a single tooth restoration. Restorability: with a crown:root ratio of at least 1:1.
2. The presence of an unrestored or minimally restored natural antagonist tooth (teeth with no more than a Class II restoration), in the same quadrant as the treated tooth (G1,2,3).
3. The presence of two unrestored or minimally restored antagonist teeth (in the same quadrants or on the contralateral side) (G4 or control).
4. Minimum height of the dental stump: 3mm.

EXCLUSION CRITERIA:

Exclusion criteria for abutment teeth:

1. Antagonist tooth with a full coverage restoration.
2. Opposing arch with fixed or removable partial denture.
3. Lack of occlusal contact points in the enamel of the control teeth.