Immediate implant placement in conjunction with guided bone regeneration and/or connective tissue grafts: an experimental study in canines

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 following 4 groups: i) gap filling with guided bone regeneration (the GBR group), ii) subepithelial connective tissue grafting (the SCTG group), iii) GBR and SCTG (the GBR/SCTG group), and iv) no further treatment (control). Non-submerged healing was provided for 4 months. Histological and histomorphometric analyses were performed. RESULTS Peri-implant tissue height and thickness favored the SCTG group (height of peri-implant mucosa: 1.14 mm; tissue thickness at the implant shoulder and ±1 mm from the shoulder: 1.14 mm, 0.78 mm, and 1.57 mm, respectively; median value) over the other groups. Bone grafting was not effective at the level of the implant shoulder and on the coronal level of the shoulder. In addition, simultaneous soft and hard tissue augmentation (the GBR/SCTG group) led to a less favorable tissue contour compared to GBR or SCTG alone (height of peri-implant mucosa: 3.06 mm; thickness of peri-implant mucosa at the implant shoulder and ±1 mm from the shoulder: 0.72 mm, 0.3 mm, and 1.09 mm, respectively). CONCLUSION SCTG tended to have positive effects on the thickness and height of the peri-implant mucosa in immediate implant placement. However, simultaneous soft and hard tissue augmentation might not allow a satisfactory tissue contour in cases where the relationship between implant position and neighboring bone housing is unfavorable

The Second EAO Consensus Conference 19-22 February 2009, Pfäffikon, Schwyz, Switzerland. Preface

status: publishe

Effect of tooth brush abrasion on the color, gloss and surface roughness of internally and externally stained monolithic ceramic materials

PURPOSE To measure the durability of the color, change in surface roughness and gloss of stained monolithic ceramic materials subjected to artificial tooth brush abrasion. MATERIALS AND METHODS Standardized specimens were manufactured from pressable lithium-disilicate glass ceramic (PC; IPS e.max Press), machinable lithium-disilicate glass ceramic (MC; IPS e.max CAD), and zirconia (ZR; Zenostar). Ceramic staining was applied before (internal; in) and after crystallization/sintering (external; ex). Of each ceramic material, specimens without staining were prepared (no staining; no). Porcelain-fused-to-metal specimens served as control (PFM). Each group consisted of 15 specimens. Tooth brushing was simulated with tooth brushing strokes of 21.6 k, 43.2 k, and 64.8 k. Color, gloss and roughness were measured at baseline and after cycle intervals. Kruskal-Wallis and paired Post-hoc Conover tests were applied to detect statistical differences between treatment groups. Differences before and after aging were calculated by Wilcoxon signed rank test (α=0.05). RESULTS In all groups, color difference (∆E) was statistically significant after aging: no-PC (P<.001, 95% CI[0.14,0.84]), no-MC (P=.003, 95% CI[0.23,1.12]), no-ZR (P=.003, 95% CI [0.33,0.62]), in-MC (P=.003, 95% CI[0.35,0.73]), in-ZR (P=.003, 95% CI[0.09,0.32]), ex-PC (P=.003, 95% CI[0.54,0.98]), ex-MC (P<.001, 95% CI[0.23,1.26]), ex-ZR (P=.003, 95% CI[0.27,0.55]), and PFM (P=.002, 95% CI[0.22,0.34]). Aging increased surface roughness and decreased the gloss within all subgroups showing statistical significance. CONCLUSIONS Color, gloss and roughness of stained monolithic ceramic materials changed significantly by means of tooth brush abrasion in vitro. Color changes were below the threshold value for the detection by the human eye (∆E 1.8)

The 4th EAO Consensus Conference 11-14 February 2015, Pfäffikon, Schwyz, Switzerland

status: publishe

Effect of different intraradicular posts on the color of the buccal gingiva at teeth restored with zirconia crowns

The purpose of this study was to test whether prosthetic treatment with different intraradicular posts influences the color of the buccal gingiva at teeth restored with zirconia crowns. A total of 31 patients in need of a full-coverage single crown at an endodontically treated premolar, canine, or incisor in the maxilla or the mandible were included. The patients were randomly assigned to receive composite build-ups using titanium (Ti), zirconia (Zi), or glass-fiber (Gf) posts or a build-up using no post at all (NP). All the teeth were restored with veneered zirconia single crowns. Spectrophotometric color measurements of the buccal gingiva were taken at the test teeth prior to and after the prosthetic treatment, and at the contralateral vital control tooth. The differences of the color components ΔL, Δa, and Δb and the total color difference ΔE between the test tooth prior to and after treatment and between the test and control tooth were calculated. The color differences were analyzed to determine whether they varied from 0 and 3.7, the threshold for detection by the human eye. Analysis of variance was performed to compare ΔE, ΔL, Δa, and Δb in the four post groups. The prosthetic treatment induced a significant color change ΔE in all the groups (Ti: ΔE1 = 6.4 ± 1.9; Zi: 7.1 ± 2.0; Gf: 6.2 ± 3.5; NP: 6.6 ± 3.5). There was no significant difference between Ti, Zi, Gf, and NP with respect to ΔE, ΔL, Δa, and Δb. Gingival color ΔE differed significantly between the test and control teeth before (Ti: ΔE = 6.8 ± 3.0; Zi: 9.0 ± 3.5; Gf: 5.7 ± 2.1; NP: 8.2 ± 2.8) and after prosthetic treatment (Ti: ΔE = 6.0 ± 2.8; Zi: 7.1 ± 2.9; Gf: 7.2 ± 3.0; NP: 6.9 ± 2.6). The use of different intraradicular posts (titanium, zirconia, glass fiber) or no post at all did not influence the color of the buccal gingiva at teeth restored with zirconia crowns. There was a significant gingival color difference between endodontically treated teeth and vital control teeth, both before and after prosthetic treatment

Esthetic assessments in implant dentistry : objective and subjective criteria for clinicians and patients

In recent years the scientific community has shown a clear interest in the esthetic outcome of implant treatment. The present paper provides an overview of the esthetic ratings that have been used in implant dentistry. A distinction can be made between objective evaluations by clinicians and subjective evaluations by patients. The former mainly include: midfacial and interproximal soft-tissue levels; two-dimensional/three-dimensional soft-tissue alterations; assessment of the color match between the natural dentition, on the one hand, and the peri-implant tissues and the reconstruction, on the other hand; and ordinal indices, such as the pink and white esthetic score. Patient's needs and judgment may differ from objective indicators of implant success and esthetics. As a result, assessing treatment on the basis of patient-reported outcomes measures should be considered important. Validated questionnaires have been used that mainly assess the impact of oral health on the overall well-being of individuals. The esthetic judgment of patients is usually based on nonstandardized questions with varying scoring methods, including visual analog scales, Likert and other category scales and open questions. The heterogeneity in scoring systems between studies may compromise proper comparison of objective and subjective esthetic outcomes between studies and therapeutic concepts

Mechanical stability of fully personalized, abutment-free zirconia implant crowns on a novel implant-crown interface

OBJECTIVES: To test the failure load and failure mode of a novel implant-crown interface specifically designed for the fabrication of fully personalized, abutment-free monolithic zirconia CAD-CAM crowns compared to conventional implant-abutment interfaces involving prefabricated or centrally manufactured abutments for zirconia CAD-CAM crowns. METHODS: Implants (N=48) were divided into groups (n=12) according to different implant-abutment interface designs: (1) internal implant connection with personalized, abutment-free CAD-CAM crowns (Abut-Free-Zr), (2) internal conical connection with customized, centrally manufactured zirconia CAD-CAM abutments (Cen-Abut-Zr), (3) prefabricated titanium base abutments from manufacturer 1 (Ti-Base-1), (4) additional prefabricated titanium base abutments from manufacturer 2 (Ti-Base-2). All specimens were restored with a screw-retained monolithic zirconia CAD-CAM molar crown and subjected to thermomechanical aging (1.200.000 cycles, 49 N, 1.67 Hz, 30° angulation, thermocycling 5-50°C). Static load until failure was applied in a universal testing machine. Failure modes were analyzed descriptively under digital microscope. Mean failure load values were statistically analyzed at a significance level of p<0.05. RESULTS: All specimens survived thermomechanical aging. The mean failure loads varied between 1332 N (Abut-Free-Zr) and 1601 N (Ti-Base-2), difference being significant between these groups (p<0.05). No differences between the other groups were seen. The predominant failure mode per group was crown fracture above implant connection (Abut-Free-Zr, 75%), abutment fracture below implant neck (Cen-Abut-Zr, 83%), crown fracture leaving an intact abutment (Ti-Base-1/Ti-Base-2 100%). CONCLUSIONS: Implant-crown interface with fully personalized, abutment-free monolithic CAD-CAM zirconia crowns exhibited similar failure loads as conventional implant-abutment interfaces (except group Ti-Base-2) involving CAD-CAM crowns with prefabricated or centrally manufactured abutment. CLINICAL SIGNIFICANCE: The new implant connection simplifies the digital workflow for all-ceramic implant reconstructions. The specific design of the implant-crown interface allows the fabrication of fully personalized, abutment-free zirconia implant crowns both in-house and in-laboratory without the need of a prefabricated abutment or central manufacturing

Randomized controlled clinical trial of all-ceramic single-tooth implant reconstructions using modified zirconia abutments: results at 5 years after loading

The objective of this trial study was to assess whether submucosal veneering of internally connected zirconia abutments influences clinical, radiographic, and technical outcomes of single-tooth implant-borne reconstructions at 5 years after loading. A total of 20 patients with 20 single-tooth implants in the anterior or premolar area of the maxilla or mandible were included. The implants were randomly restored with fixed single-tooth reconstructions using either pink-veneered customized zirconia abutments (test group = 10) or nonveneered customized zirconia abutments (control group = 10). All reconstructions were adhesively cemented with all-ceramic crowns. Follow-up examinations were performed at baseline (7 to 10 days after crown insertion) and at 1, 3, and 5 years after loading, at which points the following were assessed: periodontal parameters such as probing depth (PD), bleeding on probing (BOP), and marginal bone levels, as well as technical outcomes using the modified United States Public Health Service (USPHS) criteria. Statistical comparisons were based on the Wilcoxon-Mann-Whitney test. Sixteen patients attended the 5-year follow-up. At 5 years, the implant survival rate was 100% and the prosthetic survival rate was 94.1% (one abutment fracture in the test group). Veneering of the submucosal part of zirconia abutments resulted in significantly higher mean PD values: 3.6 ± 0.4 mm (test group) and 3.0 ± 0.5 mm (control group), P = .042. Marginal bone levels at 5 years and changes up to 5 years were not significantly different between groups (P > .05). One crown exhibited an abutment fracture and two crowns a minor chipping (17.6% overall technical complication rate). Limited by a small sample size, veneering of the submucosal part of internally connected zirconia abutments led to outcomes that were less favorable biologically (PD, BOP, and KM), but similar to nonveneered abutments radiographically and technically

Discoloration of the Peri-implant Mucosa Caused by Zirconia and Titanium Implants

The aim of the present study was to assess the discoloration of the peri-implant mucosa caused by zirconia (Zr) and titanium (Ti) dental implants with and without soft tissue grafting (STG). Zr and Ti implants were inserted in edentulous areas in pig maxillae. Spectrophotometric measurements were performed prior to and after the insertion of the implants, and following the placement of a STG on the buccal side. A significant discoloration of the mucosa was observed with a mean ΔE of 8.05 (± 2.51) (Ti) and 4.93 (± 3.18) (Zr). In conjunction with a STG, ΔE values amounted to 5.31 ± 3.50 (Ti) and 5.95 (± 3.68) (Zr). The placement of Zr implants led to less discoloration of the mucosa than Ti implants without STG

Resin-bonded fixed dental prostheses with zirconia ceramic single retainers show high survival rates and minimal tissue changes after a mean of 10 years of service

To assess the clinical outcomes of single-retainer resin-bonded fixed dental prostheses (RBFDPs) and the profilometric changes of pontic sites after a mean of 10 years in function