A randomized controlled clinical multicenter trial comparing the clinical and histological performance of a new, modified polylactide-co-glycolide acid membrane to an expanded polytetrafluorethylene membrane in guided bone regeneration procedures.

OBJECTIVES: To compare the clinical and histological outcomes of a resorbable modified polylactide/polyglycolide acid (PLGA) test membrane and a titanium-reinforced expanded polytetrafluorethylene (ePTFE) control membrane used for guided bone regeneration (GBR) around dental implants. MATERIALS AND METHODS: A total of 40 patients with peri-implant dehiscence-type defects were randomly allocated to a GBR procedure using either a modified PLGA test or an ePTFE control membrane. Soft tissue condition, implant integration, adverse events and quality of life were recorded during the 6-month healing period. At re-entry peri-implant bone defect dimensions were measured and compared with values recorded at implant/GBR surgery. A biopsy was retrieved for qualitative and quantitative histological analyses. A comparison between the groups was conducted using non-parametric statistical tests. RESULTS: Soft tissue complications were observed in five test patients and two control patients. Except for soft tissue complications and incomplete regeneration, no procedure- or device-related adverse events were observed. The vertical bone defect component was, in mean, reduced by-5.1 mm (95% CI -6.8, -3.3) in the test group and -6.9 mm (95% CI -8.2, -5.5 mm) in the control group. The mean residual vertical defect height measured 1.2 ± 2.4 mm in the test group and 0.3 ± 1.1 mm in the control group meaning a mean defect resolution of 81% in the test group and 96% in the control group (P = 0.161). The horizontal bone thickness at implant shoulder level decreased from a mean of 3.2 mm to 1.4 mm (-56%, mean -1.7 mm, 95% CI -2.3, -1.1) in the test group and from 3.3 mm to 2.5 mm (-24%, mean -0.8 mm, 95% CI -1.3, -0.3) in the control group (P = 0.022). Qualitative and quantitative histological analyses did not show significant differences in the tissue composition between groups. CONCLUSION: Peri-implant GBR was successfully performed using either of the membranes. The control membrane was able to better maintain the horizontal thickness of regenerated bone and revealed less soft tissue complications. No statistically valid evidence about the superiority of one membrane was found in any other parameters. Soft tissue dehiscences occur with both types of membranes and can impair the amount of regenerated bone.

Volume gain and stability of peri-implant tissue following bone and soft tissue augmentation: 1-year results from a prospective cohort study.

OBJECTIVES: the aim of the present study was to evaluate the dimensional changes of peri-implant tissues obtained by implant placement, bone and soft tissue augmentation, prosthetic reconstruction and 1 year of function using a new, non-invasive method for volumetric measurements. MATERIALS AND METHODS: in 16 patients, the missing central or lateral maxillary incisor was reconstructed with an implant-supported single crown. Impressions were taken before (t1), after implant placement with guided bone regeneration using DBBM and a PTFE membrane (t2), after soft tissue augmentation (t3), immediately after crown placement (t4) and 1 year later (t5). The cast models were optically scanned and digitally superimposed allowing qualitative and quantitative analysis of alterations of the labial peri-implant tissue contour. In addition, the crown length and papilla height were measured at crown placement (t4) and after 1 year (t5). RESULTS: fifteen patients were available for recall after 1 year. During therapy, a mean gain in distance in the labial direction of 1.27 ± 0.67 mm was observed after the surgical procedures. One year after crown insertion, a mean loss of 0.04 ± 0.31 mm in the labial direction was recorded. During the same period, the crown length increased by a mean of 0.22 ± 0.57 mm and the papilla height by 0.07 ± 0.61 mm. The degree and pattern of tissue change following crown insertion were highly variable between individuals, irrespective of the amount and quality of previously augmented tissues. CONCLUSIONS: the clinical procedures were effective in augmenting peri-implant tissue volume that remained stable to a high degree within 1 year after crown insertion. Large inter-individual variations regarding the tissue alterations were observed.

Crestal ridge width changes when placing implants at the time of tooth extraction with and without soft tissue augmentation after a healing period of 6 months: report of 24 consecutive cases.

The esthetic outcome of an implant-supported restoration is first of all dependent on the soft tissue volume. Since the labial bone plate resorbs in every direction after tooth extraction, even when an implant is placed immediately, most patients end up with compromised esthetics. Twenty-four patients were treated consecutively with implants placed in the maxillary anterior area at the time of tooth extraction using two different treatment modalities. The first 12 patients were treated without raising a flap, whereas a subepithelial connective tissue graft was placed using the tunnel technique in the labial area of the subsequent 12 patients at the time of tooth extraction and implant placement. The dimension of the labial volume was measured before treatment and 6 months after implant placement. The results show an average loss of volume in the nongrafted group of 1.063 mm, whereas in the grafted group, there was a slight gain of 0.34 mm. These results demonstrate the effectiveness of placing a soft tissue graft at the time of immediate implant placement in the esthetic zone.

Influence of the 3-D bone-to-implant relationship on esthetics.

There are biologic limits of the soft tissue dimension around implants; therefore, the limiting factor for the esthetic result of implant therapy is the bone level at the implant site. Clinicians must focus on the 3-D bone-to-implant relationship to establish the basis for an ideal and harmonic soft tissue situation that is stable over a long period. In some situations, missing bone is a limiting factor for esthetics; in others, it is possible to regenerate new bone around implants. As a certain amount of bone resorption occurs around implants as soon as the implant is in contact with the oral environment, the distance between an implant and adjacent tooth, as well as the distance between two implants, is as important as the bone volume on the buccal side of the implant head and in the papillary area, especially for the long-term result. This article discusses the 3-D bone-to-implant relationship and its influence on soft tissue esthetics around implants.

Six-Year Survival and Early Failure Rate of 2918 Implants with Hydrophobic and Hydrophilic Enossal Surfaces.

The aim of this chart review was to obtain an objective, quantitative assessment of the clinical performance of an implant line used in an implantological office setting. Implants with hydrophilic (INICELL) and hydrophobic (TST; both: Thommen Medical AG, Grenchen, Switzerland) enossal surfaces were compared and the cumulative implant survival rate was calculated. The data of 1063 patients that received 2918 implants (1337 INICELL, 1581 TST) was included. The average follow up time was 2.1 (1.1-5.4) years for INICELL and 4.5 (1.3-5.9) years for TST implants (Thommen Medical AG, Switzerland). In the reported period 7 implants with INICELL (0.5%) and 23 TST implants (1.5%) failed. This difference was statistically significant. The analysis of cases treated and followed up in a single implantological office for 6 years confirmed the very good clinical outcome that was achieved with both used implant lines. Within the limitations of this retrospective analysis, the overall early failure rate of the hydrophilic implants was significantly lower than that of hydrophobic implants. The use of hydrophilic implants allows the clinician to obtain less early failures, hence the interest of an up-to-date surface for the daily work of an implant practice.

Guided bone regeneration around single-tooth implants in the esthetic zone: a case series.

The objective of this case series was to evaluate the clinical and histologic outcome of guided bone regeneration around simultaneously placed implants in sites with missing buccal bone walls. Eight weeks after tooth extraction, implants were inserted, and the sites were augmented in both the horizontal and vertical dimensions using a mineralized collagen bone substitute and a nonresorbable titanium-reinforced membrane. Six months later, small hard tissue biopsy specimens were harvested from the buccal bone walls at approximately mid-height of the original defect. The histologies revealed ongoing bone formation. Clinically, an adequate amount of hard and soft tissue volume had formed.

Development, in vitro testing, and clinical use of a 3.5 mm-diameter zirconia abutment.

The use of small-diameter implants is indicated when small missing teeth have to be replaced, especially in esthetic zones. Nevertheless, the small diameter can pose a limiting factor with respect to what materials can be used for the final crown. In most cases, full-ceramic crowns in combination with a ceramic abutment are usually the material of choice for final reconstructions. To date, based on mechanical considerations, a 3.5 mm implant diameter has been a contraindication for using ceramic abutments. The authors describe here the development, in vitro testing, and clinical use of a zirconium abutment with a 3.5 mm diameter. The advantages of this small-diameter zirconia abutment include a minimum platform height that offers optimal prosthetic flexibility, and an accurate transfer of the implant position on to the master model. Furthermore, a precise rotational orientation for single-tooth restorations, optimal mechanical stability, and optimal fatigue resistance can be achieved. The microgap is minimized and protection against overload is afforded. In the reported case, high patient satisfaction was achieved due also to an esthetically pleasing final result.

Implant failure and subsequent treatment: report of a complex case.

In a 40-year-old woman, a central incisor was to be replaced with an implant-supported crown. When the implant was uncovered, the soft tissue around the implant showed an unfavorable profile: The adjacent lateral incisor showed significant loss of periodontal attachment. Subsequent soft tissue and connective tissue grafts failed to correct the problem, and an alternative treatment plan was formulated. Errors in the initial treatment, including incorrect implant position and failure to analyze the cause of the periodontal attachment loss are discussed in detail; the options for further treatment measures are outlined; and the treatment that was subsequently carried out is presented.