Clinical Efficacy of Angulated Screw-retained and Cemented Single Implant Crowns in Esthetic Region

Study Overview
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Brief Summary
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Objective: To compare the clinical efficacy of angulated screw-retained and cemented single implant crowns(SIC) in esthetic region. Methods/Design: The study was a prospective, single center, randomized controlled clinical trial. Patients with the needs of single tooth restoration in esthetics region were recruited from Oct. 2018 to Aug. 2019. Sixty patients were enrolled in the present study and they were randomly assigned into two groups: angulated screw-retained group(AG, 30 patients) and cemented group (CG,30 patients). Clinical and radiological evaluations were performed on the day of final crowns delivery and 12 months later. Implant survival rate, marginal bone loss(MBL), pro-inflammatory cytokinesin peri-implant crevicular fluid (PICF)(TNF-α, IL-6), mechanical complications, peri-implant conditions(mPI, PD, BOP%), pink esthetics score/white esthetics score (PES/ WES) and patients satisfaction were assessed.

Official Title
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Comparison of the Short-term Clinical Efficacy of Angulated Screw-retained and Cemented Single Implant Crowns in Esthetic Region: A Randomized Controlled Clinical Trial

Conditions
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Angulated Screw-retained, Esthetics

Intervention / Treatment
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* Device: angulated screw retained crown
* Device: cemented crown


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 1) age≥18; 2) Single dental implant in the esthetic region; 3) adjacent to natural teeth; 4) absence of oral mucosal disease and oral infection; 5)implants withconical connection (Nobel Active, Nobel Biocare® or NobelReplace Conical Connection, Nobel Biocare®); 6)patients with the willingness of all-ceramic permanent restorations. Exclusion Criteria: 1)Multiple implants in the esthetic region, or the restoration is a bridge; 2)Heavy smokers (>10 cigarettes/day); 3) the angle between implant axis and restoration axis>25°; 4) uncontrolled periodontitis; 5) with systematic diseases that may affect implant therapy, such as uncontrolled diabetes mellitus (Fasting blood-glucose>7.2mmol/L, Glycosylated hemoglobin >7%), current intake of bisphosphonates (treatment for malignancy), pregnant(or plan to get pregnant), with history of radiation therapy in head and neck region; 6) Unwilling to participate in the present study.

Ages Eligible for Study
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Minimum Age: 18 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: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: angulated screw-retained group(AG)<br> | Device: angulated screw retained crown<br>* ASC abutment was used in AG;<br>|
| Active Comparator: cemented group (CG)<br> | Device: cemented crown<br>* prefabricated Ti abutment was used in CG<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Marginal bone loss | Peri-apical radiographs with paralleling technique wereperformed on the day offinal restorations delivery and 1-year visit. Implant length was used as calibration reference. The distance between restoration margin and the most coronal level of implant-bone contactwas recorded. Final result was calculated as themean value of the mesial and distal sites | 1year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Survival rate. | Survival rates were defined as the percentage of success implants and remained crowns which never been replaced | 1 year | 
| Pro-inflammatory cytokinesin peri-implant crevicular fluid (PICF) | we collected the patients' PICF with the paper strip (PerioPaper Strips; Oraflow Inc., Smithtown, NY, USA) at 1year follow-up to access differences in pro-inflammatory cytokines (IL-6 and TNF-α) between two groups. | 1 year | 
| Mechanical complications | Abutments or implants fracture and screw loosening or fracture | 1 year | 
| pocket probing depth(PD) | The depth of 6 sites（mesial, middle and distal of buccal/lingual ） was measured and the average value was calculated. | 1 year | 
| PES/WES | specific dentists were asked to give scores for variables of PES (Mesial papilla, distal papilla, level of soft-tissue margin, soft-tissue contour, alveolar process and soft-tissue color and texture) and WES (Tooth form, tooth volume/outline, color, surface texture and transparency) with the 2-1-0 scoring system. Final PES/WES was the sum the two. Total scores were defined as perfect rate (PES/WES≥22), acceptable rate (22>PES/WES≥15) and unfavorable rate (PES/WES<15). | 1 year | 
| Patient's satisfaction | patient's satisfaction(PS) with aesthetics, function and comfort of the restoration at 1-year visit. 0 score was extremely dissatisfied and 10 score was extremely satisfied. We also defined the final scores as perfect rate(PS≥9), acceptable rate(9>PS≥6) and unfavorable rate (PS<6). | 1 year | 
| bleeding on probing% (BOP%) | The BOP of 6 sites（mesial, middle and distal of buccal/lingual ） was probed and the percentage of BOP(+) was calculated. | 1 year | 
| modified plaque index (mPI) | Score 0; No detection of plaque Score 1: Plaque only recognized by running a probe across the smooth marginal surface of the implant. Implants covered by titanium spray in this area always score 1. Score 2: Plaque can be seen by the naked eye. Score 3: Abundance of soft matter. | 1 year |