Markus Hof

Esthetic evaluation of single-tooth implants in the anterior maxilla following autologous bone augmentation.

OBJECTIVES Autologous bone augmentation to rebuild compromised alveolar ridge contour prior to implant placement allows for favorable three-dimensional implant positioning to achieve optimum implant esthetics. The aim of the present study was to evaluate peri-implant soft tissue conditions around single-tooth implants following bone grafts in the esthetic zone of the maxilla. MATERIALS AND METHODS Sixty patients underwent autologous bone augmentation of deficient maxillary sites prior to placement of 85 implants in the esthetic zone. In case of multiple implants per patient, one implant was randomly selected. Objective evaluation of 60 single-tooth implants was performed using the Pink-Esthetic-Score (PES) and Papilla Index (PI) and supplemented by subjective patient evaluation, as well as clinical and radiologic examination. RESULTS Objective ratings of implant esthetics were satisfactory (median PES: 11, median PI: 2) and significantly correlated with high patient satisfaction (mean VAS score: 80%). Both esthetic indices demonstrated respectable levels of inter- as well as intra-observer agreement. Poor implant esthetics (low PES and PI ratings) were significantly associated with increased anatomic crown height, while no influence of horizontal implant-tooth distance could be found. CONCLUSIONS The present investigation indicates that favorable esthetic results may be achieved in the augmented anterior maxilla. However, bony reconstruction of compromised alveolar ridges does not guarantee optimum implant esthetics.

Does Timing of Implant Placement Affect Implant Therapy Outcome in the Aesthetic Zone? A Clinical, Radiological, Aesthetic, and Patient‐Based Evaluation

PURPOSE To compare five different implant treatment protocols in the anterior maxilla, including immediate, early, and delayed implant placement, as well as implant placement in conjunction with simultaneous guided bone regeneration and implant placement 3 months following horizontal autologous bone block grafting. MATERIAL AND METHODS Aesthetic indices used included the Pink Esthetic Score (PES), Papilla Index (PI), Subjective Esthetic Score (SES), and White Esthetic Score (WES). Subjective evaluation of implant aesthetics was performed using a visual analogue scale (VAS). The VAS consisted of a 10 cm-long line representing the degree of discontent (0%) or satisfaction (100%). RESULTS A total of 153 implants in 153 patients (80 women, 73 men) were evaluated after a mean follow-up of 4.5 ± 2.9 years. Mean peri-implant bone loss was 1.6 ± 0.9 mm and not affected by treatment protocol, time after implant placement, or crown length. Papilla presence, by contrast, differed significantly between the protocols: Papilla formation was more pronounced following delayed and immediate implant placement. No statistical significance was found among treatment modalities with regard to PES, SES, or WES. Longer crowns were associated with lower PES and PI ratings and correlated with greater midfacial recession. SES was also influenced by time after implant placement and keratinized mucosa. Patient satisfaction differed significantly among treatment protocols, favoring immediate implant placement. Agreement between objective and subjective aesthetic ratings was low. CONCLUSION The present study suggests that comparable clinical, radiological, and aesthetic results can be achieved with all treatment protocols. Gingival recession, however, seems to occur in the long term irrespective of the technique used.

Primary implant stability in the atrophic sinus floor of human cadaver maxillae: impact of residual ridge height, bone density, and implant diameter

OBJECTIVES Simultaneous implant placement in conjunction with lateral or transcrestal maxillary sinus floor augmentation gives the benefit of reduction in healing times and surgical interventions. Primary implant stability, however, may be significantly reduced in resorbed residual ridges. Aim of the present study was to investigate the impact of residual bone height, bone density, and implant diameter on primary stability of implants in the atrophic sinus floor. MATERIAL AND METHODS A total of 66 NobelActive implants were inserted in the sinus floor of fresh human cadaver maxillae: 22 narrow (3.5 mm), 22 regular (4.3 mm), and 22 wide (5.0 mm) diameter implants in residual ridges of 2-6 mm height. Presurgical computed tomographic scans were acquired to assess bone height and density. Primary implant stability was evaluated by insertion torque values (ITV), Periotest values (PTV), and Osstell implant stability quotients (ISQ). RESULTS Correlations within outcomes (ITV, PTV, ISQ) were highly significant (P < 0.001). Radiographic bone density was found to significantly impact all three outcome measures (P < 0.001), while no influence of residual bone height and implant diameter could be revealed by multifactorial analysis. Consistent results were seen in all subgroups (including residual ridges of 5-6 mm height). CONCLUSIONS Bone density seems to represent the major determinant of primary stability in maxillary sinus augmentation with simultaneous implant placement (as well as 5-6 mm short implants in the maxillary sinus floor). Preoperative bone density assessment may help to avoid stability-related complications in one-stage implant treatment of the atrophic posterior maxilla.

Influence of Prosthetic Parameters on Peri-Implant Bone Resorption in the First Year of Loading: A Multi-Factorial Analysis

BACKGROUND The first year of prosthetic loading is crucial to peri-implant bone levels; however, contributing factors are yet barely understood. PURPOSE The purpose of the study is to investigate the influence of patient-, implant-, and prosthetic-related parameters on marginal bone resorption in partially edentulous patients within the first year of prosthetic loading. MATERIALS AND METHODS This retrospective multifactorial analysis involved the following influencing factors: patient gender and age, implant diameter, implant location and neck design, insertion torque, insertion depth, splinted versus single-tooth restorations, crown height space, and crown-to-implant ratio. RESULTS Mean peri-implant bone resorption around 200 dental implants was 0.98 ± 0.76 mm and significantly correlated to higher implant insertion depth (p < .001), whereas no association to prosthetic parameters could be observed. CONCLUSIONS Within the limits of the present analysis, it can be concluded that apical implant positioning may constitute a relevant determinant of early peri-implant bone resorption.

Immediate Occlusal versus Non‐Occlusal Loading of Implants: A Randomized Clinical Pilot Study

BACKGROUND Immediate occlusal and non-occlusal loading protocols have been discussed and, despite varying success rates, are considered viable in selected cases. Preoperative implant planning and intraoperative transfer are essential to the success of implant-supported reconstructions in partially or completely edentulous jaws. PURPOSE This study was performed to compare clinical outcomes of immediate occlusal versus non-occlusal loading of posterior implants. MATERIALS AND METHODS Of 19 patients with 52 screw-type implants replacing mandibular molars or premolars, nine patients with 21 implants were randomized to a study group that received immediate restorations with occlusal loading, whereas 10 patients with 31 implants were randomized to a control group that received provisional restorations without occlusal loading. Occlusal loading was defined as full loading in maximum intercuspidation. Single-tooth or splinted multiunit restorations were incorporated by screw retention or cementation. Marginal bone defects (MBD), implant survival, and implant success were evaluated 12 months after insertion. RESULTS Both groups revealed similar MBD levels consistent with previous reports. No implants were lost (overall survival: 100%) or found to fail (overall success: 100%). No significant intergroup differences were noted for any of the evaluated parameters. CONCLUSIONS Immediate restorations in partially edentulous mandibles demonstrated successful clinical and radiographic 12-month results. Larger long-term prospective studies are needed to confirm the final evidence and predictability of immediate functional loading as a standard treatment concept for partially edentulous jaws.

Meta-Analysis of Oral Implant Fracture Incidence and Related Determinants

Dental implant fracture is a rare biomechanical complication, however, one of the most serious and frustating ones as it is generally associated with implant and prosthesis failure as well as the surgical hazards of explantation and reimplantation. To gain insights into implant fracture rates and the impact of patient-, surgery-, and prosthetic-related factors, systematic review and meta-analysis of the English literature were performed. Electronic and hand searches yielded 69 relevant publications reporting on 827 fractures out of 44521 implants investigated. The overall incidence of implant fractures was 1.6%. Mean patient age at the time of implant fracture was 54 ± 11 years, and 70% occurred in males. The vast majority (85%) occurred in posterior regions of the mouth (premolar or molar positions). No tendency of increased fracture rates could be noted for short implant lengths or narrow implant diameters. Implant fractures occurred after 4.1 ± 3.5 years of loading, on average, in most cases (88%) supporting fixed restorations; however, only 56% were preceded by screw loosening. Although further investigations are needed to fully explore the characteristics and causes of this rare complication, it can be concluded that no more than 2.8% of implants fracture is within a mean loading period of 8.3 years.

Impact of Insertion Torque and Implant Neck Design on Peri-Implant Bone Level: A Randomized Split-Mouth Trial

PURPOSE The aim of this study is to assess the impact of insertion torque and implant neck design on peri-implant bone levels and gain insights into dynamic crestal tissue alterations by radiological, clinical, and biochemical examinations. MATERIAL AND METHODS In this prospective trial, a total of 84 implants (four implants in each patient) in the interforaminal region of 21 edentulous mandibles were randomly alternated according to a split-mouth design. Implant placement was performed using different insertion torques (≤20 Ncm vs >50 Ncm). In each group, one machined and one anodized implant neck design (1.5 mm length) was used in the same jaw side. Evaluation of peri-implant tissues involved radiological, clinical examination and immunoassays for interleukin-1β. RESULTS No significant influence of insertion torque or implant neck design on peri-implant bone level was found. Protein levels of interleukin-1β in the peri-implant crevicular fluid revealed no difference between both insertion torque groups and different neck designs. CONCLUSION Interactive effects of insertion torque and neck surface modification may exist; however, no clinically significant differences in marginal bone resorption after 1 year could be observed in the edentulous anterior mandible.

Does osteoporosis influence the marginal peri‐implant bone level in female patients? A cross‐sectional study in a matched collective

BACKGROUND/PURPOSE Osteoporosis, being a homeostatic imbalance, affects the remodeling of bone. Whether this catabolic bone disease influences peri-implant marginal bone remodeling remains unknown so far. The purpose of this study was to evaluate the influence of osteoporosis on peri-implant marginal bone loss (MBL) in postmenopausal women. MATERIALS AND METHODS In a matched collective, radiographic peri-implant bone level (at baseline and at follow-up examinations) was compared in healthy and osteoporotic women. General health and behavioral history of the patients were recorded using a printed questionnaire. RESULTS A best fit matching procedure generated a sample of 48 women with a total of 204 implants matched at patient and implant level that was further statistically analyzed. The mean mesial MBL-statistically corrected to report the first year-was -0.6 ± 1.2 mm (range: -5.1 to 2.2) in the healthy control group and -1.1 ± 1.3 mm (range: -5.3 to 2.2) in the osteoporotic group. Similarly, the mean distal MBL was -0.5 ± 1.3 mm (range: -5.1 to 4.8) in the healthy control group and -1.2 ± 1.3 mm (range: -4.7 to 1.6) in the osteoporotic group, respectively. The base linear regression models including solely osteoporosis and time without any other confounders revealed a significant influence of osteoporosis and time since implant placement on the MBL at the mesial and the distal implant aspect. The significance of osteoporosis on bone loss did not change incorporating the confounders: bone level at implantation, smoking, jaw, location, surface, concrement, plaque, augmentation, edentulism in opposing and implant jaw, bisphosphonates, vitamin D, fixed versus removable prosthetics, connection type. CONCLUSIONS There is no contraindication to place dental implants in osteoporotic patients. This study implicates to respect the bone level at implant placement and not to place the implant below bone level if possible.

A multicenter randomized controlled clinical trial using a new resorbable non-cross-linked collagen membrane for guided bone regeneration at dehisced single implant sites: interim results of a bone augmentation procedure

Abstract Objective To compare clinical performance of a new resorbable non‐cross‐linked collagen membrane, creos xenoprotect (CXP), with a reference membrane (BG) for guided bone regeneration at dehisced implant sites. Materials and methods This randomized controlled clinical trial enrolled patients with expected dehiscence defects following implant placement to restore single teeth in the maxillary and mandibular esthetic zone and premolar area. Implants were placed using a two‐stage surgical protocol with delayed loading. Bone augmentation material placed at the implant surface was immobilized with CXP or BG membrane. Soft tissue health was followed during the healing period, and the defect size was measured at reentry and 6 months after implant placement. Results Of the 49 included patients, 24 were treated with CXP and 25 with BG. Patient characteristics did not differ between the two arms. In the CXP arm, the defect height at implant insertion was (mean ± SD) 5.1 ± 2.1 mm (n = 24) and reduced at reentry by 81% to 1.0 ± 1.3 mm (n = 23). In the BG arm, the defect height at implant insertion was 4.9 ± 1.9 mm (n = 25) and reduced at reentry by 62% to 1.7 ± 2.1 mm (n = 24). Assuming a margin of non‐inferiority of 1 mm, CXP was non‐inferior to BG. Membrane exposure rate was highest at week 3 in both arms, reaching 16.7% for BG and 8.7% for CXP. Conclusions The new resorbable non‐cross‐linked collagen membrane facilitates bone gain to support implant placement in expected dehiscence defects. The observed trend toward higher mean bone gain and lower exposure rate with CXP compared to BG should be further investigated.

Guided bone regeneration using collagen membranes simultaneous to implant placement at compromised sites leads to reproducible results and high success rates

An implant-supported prosthesis can restore masticatory function to patients with missing teeth. A prerequisite for success is to position the implant inserted within sufficient bone to be stably osseointegrated, whilst also allowing the restoration to meet functional and esthetic needs. Unfortunately, prosthesis-driven implant sites are not always characterized by adequate bone dimensions. Furthermore, following tooth extraction, severe bone resorption often occurs. Though an array of surgical techniques are available for bone augmentation, guided bone regeneration (GBR) is one that can produce both functional and esthetic results reproducibly with high success rates, whether performed prior to or simultaneous with implant placement. Given the relevance of barrier membrane material and its individual properties to the success of GBR and, consequently, implant-supported restorations, we compared the clinical performance of a new resorbable non-crosslinked collagen membrane, creos xenoprotect (CXP), with a reference membrane Bio-Gide (BG), for GBR at dehisced implant sites. Results from a prospective, randomized clinical trial (NCT02373787) on 49 patients receiving simultaneous GBR and implant insertion demonstrated that both collagen membranes result in safe bone augmentation of dehiscence defects. Implant survival rate at reentry surgery, 6 months after implant insertion, was 100%. The new CXP membrane was statistically non-inferior to the reference BG membrane with respect to mean difference in bone defect height between implant insertion and reentry surgery ( p <0.001). Moreover, there was no difference in patient pain or quality of life between the two treatment arms. However, there were trends in improved outcomes, namely higher bone gain and lower membrane exposure rates, when CXP was used compared with BG, though not statistically significant. Together, the study confirms that, even using a simultaneous surgical approach, the CXP collagen membrane supports bone regeneration at dehisced implant sites with few complications. This demonstrates that new barrier membrane materials with improved properties, such as CXP, can provide clinical benefits to patients.