Clinical Evaluation of Teeth Prepared With Vertical Preparation Versus Deep Chamfer

Study Overview
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Brief Summary
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It has been demonstrated that a great amount of tooth structure is lost during the prosthetic preparations of abutments for full-coverage FDPs with tooth substance removal of 63% of 73%, this aggressive loss of tooth structure usually accompanied with pain and post-operative sensitivity. In comparison with the vertical preparation technique, there is less amount of tooth substance loss. this clinical study will provide benefits for practitioners and clinicians by guiding them to choose a more conservative treatment plan with the better marginal fit, clinical performance and satisfaction for the patients on the long term. rather than other benefits like less chair time, less risk for pulp injury, less time and cost

Detailed Description
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A healthy relationship between dental restorations and the periodontium is of prime importance for the clinical longevity and esthetic harmony of full coverage restorations . One of the Most Common complications, derived from fixed prostheses is gingival recession, which constitutes an important clinical concern. This problem is largely associated with iatrogenic effects produced during dental preparation or as a result of poor prosthetic fit which can cause chronic inflammation leading to gingival margin recession around the restoration .

Official Title
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Clinical Evaluation of Teeth Prepared With Vertical Preparation Technique Versus Deep Chamfer for Monolithic Zirconia Crowns

Conditions
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Single Posterior Crowns, Endodontically Treated Teeth, Decayed Teeth

Intervention / Treatment
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* Other: monolithic zirconia single posterior crowns with deep chamfer finish line
* Other: monolithic zirconia single posterior crowns with vertical finish line


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: The patients in this study will be in the range of 18-50 years Have no active periodontal or pulpal diseases, have teeth with good restorations Psychologically and physically able to withstand conventional dental procedures Able to return for follow-up examinations and evaluation No tooth mobility or grade 1 can be accepted Patients with teeth problems indicated for single posterior crowns: Badly decayed teeth Teeth restored with large filling restorations Endodontically treated teeth Malformed teeth Malposed teeth (Tilted, over-erupted, rotated, etc.) Spacing between posterior teeth Exclusion Criteria: Patients under the age of 18 or being incapable of taking out a contract Patient with active resistant periodontal diseases Patients with any medical condition that impaired correct oral hygiene a conspicuous medical or psychological history bruxism, or known allergic reaction to the materials used. pregnant female patients

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: monolithic zirconia single posterior crowns with deep chamfer finish line<br>monolithic zirconia single posterior crowns with deep chamfer finish line fabricated by cad cam machine and cemented by self adhesive resin cement. | Other: monolithic zirconia single posterior crowns with deep chamfer finish line<br>* deep chamfer of 1 mm average thickness for cervical finish line, a convergence angle of 6-12° on each side and up to 20° total, in some studies, is acceptable and occlusal reduction of 1,5-2 mm<br>|
| Experimental: monolithic zirconia single posterior crowns with vertical finish line<br>monolithic zirconia single posterior crowns with vertical finish line fabricated by cad cam machine and cemented by self adhesive resin cement. | Other: monolithic zirconia single posterior crowns with vertical finish line<br>* using special round-ended 2 degrees tapered diamond burs a non-working tip (batt bur). It has coronal diameter of 1.2 mm, apical diameter of 0.7 mm, and non- cutting end of 1 mm, which reduces or avoids damage to the connective attachment and allows a tooth-guided preparation procedure<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Marginal adaptation | Assessed using the modified usphs criteria by Discrete (scores) Alpha (A) No visible evidences of crevice along the margins; no catch or penetration of the explorer. Bravo (B) Visible evidence of crevice and/or catch of explorer; no penetration of the explorer. Charlie (C) Visible evidence of crevice and penetration of the explorer. | 1 year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Fracture of the restoration | Assessed using the modified usphs criteria by Discrete (scores) Alpha (A) Smooth surface of the restoration (shiny after air drying) Bravo (B) Dull surface and/or chipping of porcelain that does not impair function Charlie (C) Chipping of veneering material impairing esthetics and function and/or exposing framework material | 1 year | 
| gingival inflammation | Assessed using the modified usphs criteria by Discrete (scores) Alpha (A) Normal gingiva Bravo (B) Mild inflammation - slight change in color and slight edema but no bleeding on probing; Charlie (C) Moderate inflammation redness, edema, and glazing, bleeding on probing; | 1 year | 
| Recurrent caries | Assessed using the modified usphs criteria by Discrete (scores) Alpha (A) No caries present Bravo (B) Caries present | 1 year |