Table 1.
Overview of study variables and data collection methods.
| Type of variable | Scale | Instrument | Time point | ||
|---|---|---|---|---|---|
| Outcomes | Biological complications | Bleeding on probing | Modified gingival index (REF) (0: no bleeding when a periodontal probe is passed along the gingival margin adjacent the implant; 1: isolated bleeding spots visible; 2: blood forms a confluent red line on margin; 3: heavy or profuse bleeding) | Periodontal probe (Click-Probe 3/5/7/10 blue, KerrHave, Bioggio, Switzerland) | T1–T6 |
| Probing depth | Distance (mm) from the mucosal margin to the bottom of the deepest clinical probing site on the mesial, distal, buccal, and lingual sides of the implant. Per implant, the mean value of those sides is calculated | ||||
| Marginal bone height | Vertical distance (mm) from implant shoulder to superior border of marginal bone in mesial and distal sides; the difference in marginal bone height between subsequent radiographs is calculated |
Image acquisition: Vertical bitewing radiographs, parallel cone technique, phosphor plates (VistaScan Image Plate, Dürr Dental, Bietigheim-Bissingen, Germany), and individually putty-modified plate positioning devices Image processing: Emago software (version 6.0), Oral Diagnostic Systems, Amsterdam, The Netherlands |
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| Loss of osseointegration | Presence/absence | Clinical and radiographic evaluation | |||
| Technical complications | Suprastructure | Complete or incomplete fracture of veneer, fracture of framework, loosening of occlusal screw or fracture of luting cement, fracture of occlusal screw | Clinical and radiographic evaluation | T3, T4, T5, T6 | |
| Abutment | Loosening or fracture of abutment screw, fracture of abutment | ||||
| Implant body | Fracture | ||||
| Other | E.g., appearance of wear facets, loss of occlusal screw seal, etc. | ||||
| Biofilm composition | Shannon diversity index of peri-implant submucosal biofilm, collected from the mesial, distal, lingual, and buccal sides of each implant |
Biofilm collection and storage: Sterile paper points (Henry Schein Absorbent Points #504 medium, Henry Schein, Melville, NY, USA), tubes (Axygen Self-standing, clear, sterile Scientific Screw Cap Tubes, 2.0 ml, Axygen, Union City, CA, USA) and stored in the laboratory of ACTA at −80 °C Biofilm analysis: genome analysis of bacterial samples, open-ended sequencing technique |
T1, T4, T5 | ||
| Covariates/confounders | Smoking status | Never, occasional, former, current | Questionnaire (Hukkinen et al. REF) | T1, T5 | |
| Awake bruxism | Never, rarely, sometimes, often, always | Questionnaire (Oral behaviors Checklist REF) | |||
| Plaque accumulation | Modified plaque index (REF) (0: no detection of plaque; 1: plaque only recognized by running a periodontal probe across the smooth marginal surface of the implant. Implants covered by titanium spray in this area always score 1; 2: plaque can be seen by the naked eye; 3: abundance of soft matter) | Clinical examination | T1, T2, T5 | ||
| Periodontal parameters | Number of clinical pockets with probing depths of ≥5 mm and bleeding index of all present natural elements and implants (except implants under study) | Periodontal probe (Click-Probe 3/5/7/10 blue, KerrHave, Bioggio, Switzerland) | |||
| Sample descriptive variables | Occluding pairs of natural teeth | Number of pairs between upper and lower equivalent natural teeth | Clinical examination | T1, T5 | |
| Implant geometrical characteristics | Type of implant (manufacturer and system), implant size (diameter and length, in mm) | Electronic health record | T1 | ||
| Implant loading characteristics | Time of loading with the definitive suprastructure (immediate, i.e., within 1 week after implant placement; early, i.e., between 1 week and 2 months; or late, i.e., after 2 months), bone or soft tissue augmentation procedures, bone quality (REF), and position of implant (within arch, lower or upper jaw) | Electronic health record | T1 | ||
| Prosthetic characteristics | Type of abutment (material, fabrication method), type of implant-supported suprastructure (single crown, fixed partial denture with or without cantilever), retention type (cemented or screw-retained) | Electronic health record | T2 | ||
| Antagonist status | Structure of opposing occlusal contact(s) (natural tooth, implant or none), type of restorative material present on opposing supporting cusp(s), and occlusal contact of implant-supported restoration with antagonists during maximum intercuspation, protrusion, and/or laterotrusions | Electronic health record and clinical examination with a 12 μm occlusal foil (Hanel occlusion foil 12 μm, Coltene, Langenau, Germany) | T2, T5 | ||
T1: baseline (impression appointment), T2: 2 weeks (suprastructure placement), T3: 6 weeks, T4: 3 months, T5: 1 year, T6: 2 years.