Daniel S Thoma

Center for Dental Medicine, University of Zurich · Clinic of Reconstructive Dentistry

Objectives Working Group 5 was convened to discuss and find consensus on the topics of implant placement and loading protocols associated with single missing teeth in the anterior maxilla (aesthetic zone). Consensus statements, clinical recommendations, patient perspectives and future research suggestions were developed and presented to the plenary...

Aim: To define immunophenotypes of stromal inflammatory and endothelial cells and fibroblasts 3-months post-augmentation of the peri-implant soft tissue using a porcine cross-linked collagen matrix (VCMX). Methods: Peri-implant soft tissue samples were obtained from 12 patients at the lining mucosa (LM) - masticatory mucosa (MM) junction, before an...

Aim: To compare subepithelial connective tissue grafts (SCTG) versus guided bone regeneration (GBR) for the treatment of small peri-implant dehiscence defects in terms of profilometric (primary outcome), clinical, and patient-reported outcome measures (PROMs). Methods: Sixteen patients who presented with small buccal bone dehiscences (≤3 mm) fol...

Objectives: To test whether soft tissue volume augmentation using a collagen matrix (VCMX) leads to noninferior results in terms of gain of mucosal thickness at single implant sites, compared to connective tissue grafts (SCTG). Methods: The study was designed as a multi-center randomized controlled clinical trial. Subjects in need of soft tissue...

Objectives: To assess survival rates and compare technical, biological, and esthetic outcomes of customized zirconia and titanium abutments at 13 years post loading. Materials and methods: Initially, 22 patients with 40 implants in posterior regions were included. The sites were randomly assigned to 20 customized zirconia abutments with cemented...

Statement of Problem: Emerging evidence indicates that the emergence profile and subsequent restorative angle play a crucial role in clinical outcomes and can potentially affect the development and progression of peri-implant diseases. However, the traditional evaluation of the emergence profile and angle has been limited to mesial and distal sites...

Purpose: The aim of this study was to compare changes in soft and hard tissue and the histologic composition following early implant placement in sites with alveolar ridge preservation or spontaneous healing (SH), as well as implant performance up to 1 year after crown insertion. Methods: Thirty-five patients with either intact buccal bone plate...

Aims: To assess the clinical concept of patient treatment with fixed tooth- and implant-supported restorations in a university-based undergraduate program after 13 - 15 years. Methods: Thirty patients (mean age 56 years) who had received multiple tooth- and implant-supported restorations were recalled after 13-15 years. The clinical assessment c...

Objectives Our aim is to study titanium remains in a bone model during standardized implantoplasty under different isolation and protective modalities. Material and methods Forty implants were placed in artificial spongy bone blocks mimicking a horizontal bone loss and implant neck protrusion of 5 mm. Samples were randomly divided into four groups...

Aim: Lack of consistently reported outcomes limits progress in evidence-based implant dentistry and quality of care. The objective of this initiative was to develop a core outcome set (COS) and measurements for implant dentistry clinical trials (ID-COSM). Materials and methods: This Core Outcome Measures in Effectiveness Trials (COMET)-registere...

Aim: Lack of consistently reported outcomes limits progress in evidence-based implant dentistry and quality of care. The objective of this initiative was to develop a core outcome set (COS) and measurements for implant dentistry clinical trials (ID-COSM). Materials and methods: This Core Outcome Measures in Effectiveness Trials (COMET)-registere...

Objectives: to evaluate the volumetric changes and peri-implant health at implant sites with and without previous soft tissue grafting over a 12-year observation period. Materials and methods: Eighteen patients received dental implants and simultaneous guided bone regeneration in the esthetic zone (15-25) for dental rehabilitation. Three months...

Background: Peri-implant mucosa color (PMC) seems to be one of the main parameters affecting the esthetic outcome of implant therapy. However, more emphasis should be given to its assessment and reporting. Purpose: To describe the available evidence on methods to assess and report the color of the peri-implant mucosa (PMC) and the respective cli...

OBJECTIVE To assess time efficiency and the efficacy of the prosthetic manufacturing for implant crown fabrication in a centralized workflow applying computer aided design and computer aided manufacturing (CAD-CAM). MATERIAL AND METHODS Fifty-nine patients with one posterior implant each, were randomly allocated to either a centralized digital work...

Objective: This report aims to present an infra- and labio-version of the implants relative to the surrounding teeth in an older patient. Background: Infra-positioning of dental implants has been sometimes observed in young adults but not in older patients. Materials and methods: Two implants were placed in both central incisor areas in a 63-y...

Background: Interventions to augment the mucosal thickness around dental implants are indicated to optimize esthetics and maintain peri-implant health. However, there is a lack of clinical data on the long-term performance of soft tissue substitutes, such as volume-stable collagen matrix (VCMX), compared to autogenous grafts, such as subepithelial...

Objectives To analyze the influence of compression on tissue integration and degradation of soft tissue substitutes. Material and methods Six subcutaneous pouches in twenty-eight rats were prepared and boxes made of Al2O3 were implanted and used as carriers for soft tissue substitutes: a collagen matrix (MG), two volume-stable collagen matrices (F...

Objective: To assess time efficiency and the efficacy of the prosthetic manufacturing for implant crown fabrication in a centralized workflow applying computer aided design and computer aided manufacturing (CAD-CAM). Material and methods: Fifty-nine patients with one posterior implant each, were randomly allocated to either a centralized digital...

Objectives: To analyze changes in radiographic bone density around short implants with and without cantilevers at 5 years post-loading. Materials and methods: Thirty-six patients with two adjacent posterior missing teeth participated in this randomized controlled clinical trial. All patients were randomly allocated to receive either two short im...

Objectives: To describe the methodology of the "L-shape" technique in guided bone regeneration (GBR) with simultaneous implant placement and report on the clinical, esthetic, and patient satisfaction outcomes up to 14 years of follow-up. Material and methods: Fourteen patients treated with the "L-shape" technique were included in this retrospect...

The aim of this study was to compare patient‐reported outcome measures (PROMs) of soft tissue substitutes versus autogenous grafts for soft tissue augmentation procedures at implant sites. Comprehensive and systematic literature searches were performed until December 2021. A focused question was formulated based on the Population, Intervention, Com...

Background: Interventions to augment the mucosal thickness around dental implants are indicated to optimize aesthetics and maintain peri-implant health. However, there is a lack of clinical data on the long-term performance of soft tissue substitutes (VCMX) compared to autogenous grafts (SCTGs). The aim of the present randomized controlled trial wa...

Aim To describe and compare the pontic site development for fixed-dental prostheses (FDPs) with and without soft tissue grafting up to one-year post insertion of FDPs. Materials and methods A convenience sample of 24 patients participating in an ongoing RCT was provided with three-unit tooth-borne FDPs. Six patients received a subepithelial connec...

Objectives: To test whether or not the emergence profile (CONVEX or CONCAVE) of implant-supported crowns influences the mucosal margin stability up to 12 months post insertion of the final restoration. Materials and methods: Forty-seven patients with a single implant in the anterior region were randomly allocated to one of three groups:1) CONVEX...

The objective of this study was to assess volumetric and linear changes of buccal mucosal thickness at implant sites following soft tissue augmentation with a volume-stable collagen matrix (VCMX). Soft tissue augmentation using a VCMX was performed in 12 patients at the time of implant placement. Hydrocolloid impressions were taken prior to surgery...

Aim: To identify the factors associated with buccal peri-implant soft tissue dehiscences (BSTDs) and their frequency of occurrence. Materials and methods: Randomized controlled trials, controlled clinical trials, cohort studies, and case series assessing the frequency of occurrence of BSTD were included. BSTD was defined as an apical migration o...

Objectives: The aim of this study was to comprehensively assess the literature in terms of the effect of peri-implant mucosal thickness on esthetic outcomes and the efficacy of soft tissue augmentation procedures to increase the mucosal thickness with autogenous grafts or soft tissue substitutes. Material and methods: Two systematic reviews (SR)...

Objectives: In systematically healthy patients with an implant-supported fixed restoration (P), what is the influence of thin (E) as compared to thick (C) peri-implant soft tissues on aesthetic outcomes (O)? Methods: Following an a priori protocol, a literature search of six databases was conducted up to August 2020 to identify prospective/retro...

Aim: To test the effect of membrane fixation on ridge volume stability and new bone formation applying guided bone regeneration (GBR). Materials and methods: In eight beagle dogs, after bilateral extraction of the maxillary premolars, a box-shaped defect was created on each side. All defect sites were augmented with a particulate bone substitute ma...

Aim: To assess radiographic, restorative, clinical and technical outcomes as well as patient satisfaction of directly veneered zirconia restorations cemented on non-original titanium bases over 5 years. Material and methods: Twenty-four patients with a single missing tooth in the aesthetic zone were recruited. All patients received a two-piece i...

Aim: To test the effect of membrane fixation on ridge volume stability and new bone formation applying guided bone regeneration (GBR). Materials and methods: In eight beagle dogs, after bilateral extraction of the maxillary premolars, a box-shaped defect was created on each side. All defect sites were augmented with a particulate bone substitute...

Clinical research in implant dentistry has always been driven by a meticulous search for millimetres, percentages, and dichotomous assessments of the presence or absence of any parameter supposed to be clinically critical. In recent years, there has been a paradigm shift from standard clinical parameters such as marginal bone level changes, changes...

Objectives: To test whether or not a chairside workflow (CHAIR) is similar to a labside workflow (LAB) in terms of efficacy (primary outcome) and efficiency (secondary outcome). Material and methods: Eighteen subjects in need of a single-tooth restoration in the posterior region of the maxilla or mandible were consecutively recruited and randoml...

Clinical research in implant dentistry has always been driven by a meticulous search for millimetres, percentages, and dichotomous assessments of the presence or absence of any parameter supposed to be clinically critical. In recent years, there has been a paradigm shift from standard clinical parameters such as marginal bone level changes, changes...

Aim: To identify and report outcome measures and methods of assessment on soft tissue augmentation interventions in the context of dental implant therapy reported in clinical studies published in the last 10 years. Material and methods: The protocol of this PRISMA 2020-compliant systematic review was registered in PROSPERO (CRD42021252214). A li...

The management and prevention of soft tissue complications is of key importance in modern implant dentistry and influences biologic and esthetic outcomes. The assessment of the soft tissue conditions from a quantitative and qualitative perspective should, therefore, be part of the overall treatment plan. Such an assessment dictates a potential indi...

Aim: The aim of this study was to identify the additional effects of collagen membrane (CM) and of synthetic bone substitute (BS) on lateral bone augmentation of chronic peri-implant defect with titanium mesh (TM). Materials and methods: Atrophic alveolar ridge was induced in 6 canine mandibles and 5 peri-implant defects were achieved in each he...

Aim: To assess the frequency and quantity of interproximal contact loss (ICL) between implant restorations and adjacent teeth after at least 10 years of follow-up (FU). Methods: Thirty-nine patients (median age 57.3 years) with 80 implants were re-examined at least 10 years after insertion of final restorations (single-crowns or fixed dental pro...

Objectives: To compare screw-retained and cemented all-ceramic implant-supported single crowns regarding biological and technical outcomes over a 5-year observation period. Materials and methods: in 44 patients, 44 two-piece dental implants were placed in single tooth gaps in the esthetic zone. Patients randomly received a screw-retained (SR) or...

Aim: To identify and report outcome measures and methods of assessment on soft tissue augmentation interventions in the context of dental implant therapy reported in clinical studies published in the last 10 years. Material and methods: The protocol of this PRISMA 2020-compliant systematic review was registered in PROSPERO (CRD42021252214). A lite...

Aim: To determine the effect of (1) implant placement timing and (2) the type of soft tissue graft in terms of ridge profile changes. Materials and methods: Four implant treatment modalities were applied in the mesial root areas of the third and fourth mandibular premolars of 10 mongrel\ dogs alongside connective-tissue graft (CTG) and volume-st...

Objectives: To assess clinical, technical, biological, and radiographic outcomes of implants supporting fixed restorations using two types of dental implants with non-matching implant-abutment junctions at 8 years. Materials and methods: Sixty-four patients were randomly assigned to receive one of two implant systems (S1 or S2) and eventually fi...

Objectives: to compare cemented and screw-retained one-piece zirconia-based restorations in terms of clinical, radiographic and technical outcomes 5 years after insertion. Materials and methods: Thirty-four patients with single-tooth implants were randomly restored with either a cemented lithium disilicate crown on a one-piece customized zirconi...

Background: Emerging evidence suggests that the prosthetic design of implant-supported crowns, namely restorative angles may have an impact on peri-implant marginal bone remodeling, but studies supporting this hypothesis are lacking. Whether this hypothesis applies to Ti Bases remains unknown. Aim/Hypothesis: To assess whether or not the restora...

AimThis study aims to examine the composition of lining and masticatory mucosa at the pre- and post-soft tissue augmentation procedures with a volume-stable cross-linking collagen matrix (VCMX) in humans.Materials and methodsIn 12 patients, single implant sites were augmented with a VCMX. Biopsies were obtained including masticatory (MM) and lining...

Objectives To assess long-term outcomes of implants placed in conjunction with guided bone regeneration (GBR) with or without recombinant human bone morphogenetic protein-2 (rhBMP-2). Materials and Methods 11 patients with at least two lateral bone defects (split-mouth design) received a total of 34 implants. The defects were treated with a xenoge...

Purpose To determine whether collagen membrane (CM) fixation enhances guided bone regeneration in standardized defects. Materials and methods Four 8-mm-diameter defects were surgically made in eight rabbit calvaria, and randomly allocated into four groups: control (empty), unfixed-CM, fixed-CM, and unfixed-CM with bone graft (BG+CM) (positive cont...

Purpose: This study was conducted to assess the effect of hard and/or soft tissue grafting on immediate implants in a preclinical model. Methods: In 5 mongrel dogs, the distal roots of P2 and P3 were extracted from the maxilla (4 sites in each animal), and immediate implant placement was performed. Each site was randomly assigned to 1 of the fol...

Aim To assess the effect of Schneiderian membrane (SM) perforation on bone formation by applying a particulate deproteinized bovine bone mineral (PBBM). Materials and Methods Bilateral sinus augmentation was performed in eight rabbits. The same amount of PBBM was placed at a sinus where the SM was intentionally perforated for the perforation group...

Objective: To systematically review the dental literature for clinical studies reporting on production time, effectiveness and/or costs of additive and subtractive computer-aided manufacturing (CAM) of implant prostheses. Materials and methods: A systematic electronic search for clinical studies from 1990 until June 2020 was performed using the...

OBJECTIVES The task of working Group 2 at the 6th Consensus Meeting of the European Association for Osseointegration was to comprehensively assess the effects of soft tissue augmentation procedures at dental implant sites on clinical, radiographic and patient-reported outcome measures (PROMs) including an overview on available outcome measures and...

Objectives To test whether or not primary bone augmentation using xenograft blocks infused with BMP-2 or autogenous bone blocks leads to similar results regarding implant survival and 3D marginal soft tissue contours. Methods Twenty-four patients with an insufficient ridge width for implant placement in need of primary augmentation were randomly a...

Objectives To assess the osseointegration of calcium-coated (CS) and chemically modified, sandblasted, large-grit, acid-etched (MS) dental implants with a lack of primary mechanical stability. Materials and Methods Eighteen implants in CS and MS groups each were loosely placed in the mandible of 6 mongrel dogs and allowed to heal for 2, 4 and 8 we...

Objectives To test whether or not the use of a short implant with a cantilever results in similar clinical and radiographic outcomes compared to two adjacent short implants with single tooth reconstructions. Material and Methods Thirty-six patients with two adjacent missing teeth in the posterior region were randomly assigned to receive either one...

Objectives The task of working Group 2 at the 6th Consensus Meeting of the European Association of Osseointegration was to comprehensively assess the effects of soft tissue augmentation procedures at dental implant sites on clinical, radiographic, and patient-reported outcome measures (PROMs) including an overview on available outcome measures and...

Evidence on the use of short dental implants has substantially increased in recent years. Consequently, short dental implants have expanded treatment options. Specific clinical indications currently encompass sites with a limited ridge height due to nearby anatomical structures: the maxillary sinus or the alveolar nerve in the lower jaw. In compari...

Objectives To assess clinical and radiographic outcomes as well as the profilometric contour alterations of peri‐implant hard and soft tissues around single implants treated with simultaneous guided bone regeneration (GBR) at 5 years. Materials and methods Twenty‐seven patients presenting with a single tooth gap in the esthetic zone received a two...

Objectives To analyse whether there is a difference in marginal bone levels (MBL) and the respective changes between cemented and screw‐retained reconstructions at 3 and 5 years of loading. Methods Radiographic data from 14 prospective multi‐centre clinical trials following implant loading with fixed cemented (CEM) or screw‐retained (SCREW) recons...

AimTo assess histopathological and histomorphometric outcomes of soft tissue volume augmentation procedures at pontic sites using a volume-stable cross-linked collagen matrix (VCMX) and a non-cross-linked collagen matrix (XCM).Materials and methodsIn twelve adult beagle dogs, the mandibular premolars and first molar were hemisected and the mesial r...

Purpose: To assess the clinical, technical, and esthetic outcomes of directly veneered zirconia abutments cemented onto non-original titanium bases over 3 years. Materials and methods: A total of 24 healthy patients with a single missing tooth in the maxilla or mandible (incisors, canines, or premolars) received a two-piece implant with a screw-...

Objectives To assess contour changes of peri-implant tissues comparing a one- and a two-piece dental implant system over 12 years. Materials and methods Patients seeking implant therapy were enrolled and randomly allocated to receive implants (a one-piece (STM) or a two-piece (BRA) system). Impressions were taken at the time of insertion of the fi...

Information regarding profilometric changes at a soft tissue level following implant placement with different protocols is insufficient. Therefore, this study aimed to comparatively investigate the profilometric tissue changes with respect to late implant placement following alveolar ridge preservation (LP/ARP) and early implantation (EP) in period...

Objective To compare the clinical, radiographic, and histological healing patterns between the immediate and delayed applications of bone morphogenetic protein-2 (BMP-2) in damaged extraction sockets in dogs.Materials and methodsThe distal roots of the fourth premolars of the mandible were extracted bilaterally in five beagle dogs, and buccal bone...

Objectives To analyze the soft tissue morphology under healthy and experimental mucositis conditions comparing zirconia and titanium implants. Methods Forty‐two patients with two adjacent missing teeth received one zirconia (Zr) and one titanium (Ti) implant, with the mesial and distal position randomized. At 3 months, half of the patients were in...

Objectives: To investigate in vitro release kinetics and ossification patterns of bone morphogenetic protein-2 soaked collagenated porcine bone mineral (BMP-2/CPBM) in rabbit sinuses. Methods: Release kinetics of BMP-2/CPBM was determined in vitro up to 56 days. In 16 rabbits, BMP-2/CPBM (BMP group) and CPBM alone (control group) were bilaterall...

Purpose: The purpose of this study was to examine the local tissue reactions associated with 3 different poly(lactic-co-glycolic acid) (PLGA) prototype membranes and to compare them to the reactions associated with commercially available resorbable membranes in rats. Methods: Seven different membranes-3 synthetic PLGA prototypes (T1, T2, and T3) a...

Aim: To assess changes in the position of the mucogingival junction (MGJ) after an apically positioned flap (APF) with collagen matrix performed at sites with or without previous guided bone regeneration (GBR). Materials and methods: Dental implants were placed with or without GBR (group GBR or nonGBR) depending on the available ridge width in 3...

Objective: to compare the efficacy of a collagenated synthetic bone substitute (C-SBS) to a particulated synthetic bone substitute (P-SBS) in volume maintenance and new bone formations in a rabbit sinus model. Materials and methods: Either C-SBS or P-SBS was grafted in both sinuses of 16 rabbits. Four (N = 8) or 12 (N = 8) weeks after the surger...