Early bacterial colonization and soft tissue health around zirconia and titanium abutments: an in vivo study in man

Aim: To compare the early bacterial colonization and soft tissue health of mucosa adjacent to zirconia (ZrO₂) and titanium (Ti) abutment surfaces in vivo. Materials and methods: Twenty edentulous subjects received two endosseous mandibular implants. The implants were fitted with either a ZrO₂ or a Ti abutment (non‐submerged implant placement, within‐subject comparison, left‐right randomization). Sulcular bacterial sampling and the assessment of probing pocket depth, recession and bleeding on probing were performed at 2 weeks and 3 months post‐surgery. Wilcoxon matched‐pairs, sign‐rank tests were applied to test differences in the counts of seven marker bacteria and the clinical parameters that were associated with the ZrO₂ and Ti abutments, at the two observation time points. Results: ZrO₂ and Ti abutments harboured similar counts of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Peptostreptococcus micros, Fusobacterium nucleatum and Treponema denticola at 2 weeks and 3 months. Healthy clinical conditions were seen around both ZrO₂ and Ti abutments at all times, without significant differences in most clinical parameters of peri‐implant soft tissue health. Mean probing depths around Ti abutments were slightly deeper than around ZrO₂ abutments after 3 months (2.2 SD 0.8 mm vs. 1.7 SD 0.7 mm, P=0.03). Conclusions: No difference in health of the soft tissues adjacent to ZrO₂ and Ti abutment surfaces or in early bacterial colonization could be demonstrated, although somewhat shallower probing depths were observed around ZrO₂ abutments after 3 month. To cite this article:
van Brakel R, Cune MS, van Winkelhoff AJ, de Putter C, Verhoeven JW, van der Reijden W. Early bacterial colonization and soft tissue health around zirconia and titanium abutments: an in vivo study in man
Clin. Oral Impl. Res. 22 , 2011; 571–577
doi: 10.1111/j.1600‐0501.2010.02005.x     

The effect of zirconia and titanium implant abutments on light reflection of the supporting soft tissues

Objectives: To determine the difference in light reflection of oral mucosa covering titanium (Ti) or zirconia (ZrO₂) abutments as it relates to the thickness of the covering mucosa. Material and methods: Fifteen anterior implants (Astra Osseo speed^®) in 11 patients were fitted with a Ti or a ZrO₂ abutment (cross‐over, within‐subject comparison). Hyper‐spectral images were taken with a camera fitted on a surgical microscope. High‐resolution images with 70 nm interval between 440 and 720 nm were obtained within 30 s (1392 × 1024 pixels). Black‐ and white‐point reference was used for spatial and spectral normalization as well as correction for motion during exposure. Reflection spectra were extracted from the image on a line mid‐buccal of the implant, starting 1 mm above the soft tissue continuing up to 3 mm apically. Results: Median soft tissue height is 2.3 mm (min: 1.2 mm and max: 3.1 mm). The buccal mucosa rapidly increases in the thickness, when moving apically. At 2.2 mm, thickness is 3 mm. No perceivable difference between the Ti and ZrO₂ abutment can be observed when the thickness of the mucosa is 2±0.1 mm (95% confidence interval) or more. Conclusion: It is expected that the difference in light reflection of soft tissue covering Ti or ZrO₂ abutments is no longer noticeable for the human eye when the mucosa thickness exceeds 2 mm. Haemoglobin peaks in the reflection spectrum can be observed and make hyper‐spectral imaging a practical and useful tool for measuring soft tissue health. To cite this article:
van Brakel R, Noordmans HJ, Frenken J, de Roode R, de Wit GC, Cune MS. The effect of zirconia and titanium implant abutments on light reflection of the supporting soft tissues.
Clin. Oral Impl. Res. 22 , 2011; 1172–1178
doi: 10.1111/j.1600‐0501.2010.02082.x     

Randomized controlled clinical trial of customized zirconia and titanium implant abutments for canine and posterior single-tooth implant reconstructions: preliminary results at 1 year of function

Objectives: The aim of this study was to test whether or not customized zirconia abutments exhibit the same survival rates in canine and posterior regions as titanium abutments, and to compare the esthetic result of the two abutment types. Material and methods: Twenty‐two patients with 40 implants in posterior regions were included and the implant sites were randomly assigned to 20 customized zirconia and 20 customized titanium abutments. All‐ceramic (AC) and metal–ceramic (MC) crowns were fabricated. In all except two cases, the crowns were cemented on the abutments using resin or glass‐ionomer cements. Two zirconia reconstructions were screw retained. At baseline, 6 and 12 months, the reconstructions were examined for technical and biological problems. Probing pocket depth (PPD), plaque (Pl) and bleeding on probing (BOP) were assessed and compared with natural control teeth. Furthermore, the difference of color (ΔE) of the peri‐implant mucosa and the gingiva of control teeth was evaluated by means of a spectrophotometer (Spectroshade). The data were analyzed with Student's unpaired t‐test, ANOVA and regression analyses. Results: Twenty patients with 19 zirconia and 12 titanium abutments were examined at a mean follow‐up of 12.6±2.7 months. The survival rate for reconstructions and abutments was 100%. No technical or biological problems were found at the test and control sites. Two chippings (16.7%) occurred at crowns supported by titanium abutments. No difference was found regarding PPD (meanPPD_ZrO2 3.4±0.7 mm, mPPD_Ti 3.3±0.6 mm), Pl (mPl_ZrO2 0.2±0.3, mPl_Ti 0.1±1.8) and BOP (mBOP_ZrO2 60±30%, mBOP_Ti 30±40%) between the two groups. Both crowns on zirconia and titanium abutments induced a similar amount of discoloration of the soft tissue compared with the gingiva at natural teeth (ΔE_ZrO2 8.1±3.9, ΔE_Ti 7.8±4.3). Conclusions: At 1 year, zirconia abutments exhibited the same survival and a similar esthetic outcome as titanium abutments.     

Cement thickness at implant‐supported single‐tooth Lava assemblies: a scanning electron microscopic investigation

Objectives: The fit of implant‐supported single‐tooth Lava zirconia assemblies was investigated in this study. The implant–abutment interface, the interface between the metallic and the zirconia portion of the abutment and the interface between Lava abutments and copings were evaluated. The adaptation of titanium abutments to implants and Lava copings was investigated as a control. Material and methods: Twenty implants were randomly assigned and connected to Lava abutments (group 1) or titanium abutments (group 2). All specimens were subjected to scanning electron microscopy (SEM) analysis of the fixture/abutment fit. Afterwards, specimens were luted to Lava copings and subjected to a SEM evaluation of the marginal external adaptation of the abutments with the copings. Finally, the samples were embedded in resin, sectioned and subjected to SEM analysis of the following interfaces; group 1: titanium/zirconia interface (between the constitutive components of the Lava abutment) and the zirconia/zirconia interface (between the Lava abutment and the coping); group 2: the titanium/zirconia interface (between the titanium abutment and the Lava coping). Non‐parametric analysis of variance and a post hoc test were used for statistical analysis. Results: Significant differences emerged in the cement thickness between titanium and zirconia components of the Lava abutments as compared with the thickness measured at the interface between Lava copings and the abutments investigated. No differences were found in cement thickness between Lava copings and the two different abutments. Conclusions: When Lava abutments are used, the most critical cement thickness is the internal interface between its titanium and zirconia components. Lava coping adaptation for both Lava and titanium abutments is within the clinical acceptable range. To cite this article:
Apicella D, Veltri M, Chieffi N, Balleri P, Ferrari M. Cement thickness at implant‐supported single‐tooth Lava assemblies: a scanning electron microscopic investigation.
Clin. Oral Impl. Res. 21 , 2010; 747–750.
doi: 10.1111/j.1600‐0501.2009.01882.x     

Fatigue resistance and failure mode of novel-design anterior single-tooth implant restorations: influence of material selection for type III veneers bonded to zirconia abutments

Objectives: This study assessed the fatigue resistance and failure mode of type III porcelain and composite resin veneers bonded to custom zirconia implant abutments. Material and methods: Twenty‐four standardized zirconia implant abutments were fabricated. Using the CEREC 3 machine, type III veneers of standardized shape were milled in ceramic Vita Mark II or in composite resin Paradigm MZ100. The intaglio surfaces of the restorations were hydrofluoric acid etched and silanated (Mark II) or airborne‐particle abraded and silanated (MZ100). The fitting surface of the abutments was airborne‐particle abraded, cleaned, and inserted into a bone level implant (BLI RC SLActive 10 mm). All veneers (n=24) were adhesively luted with a zirconia primer (Z‐Prime Plus), adhesive resin (Optibond FL) and a pre‐heated light‐curing composite resin (Filtek Z100). Cyclic isometric chewing (5 Hz) was simulated, starting with a load of 40 N, followed by stages of 80, 120, 160, 200, 240, and 280 N (20,000 cycles each). Samples were loaded until fracture or to a maximum of 140,000 cycles. Groups were compared using the life table survival analysis (Logrank test at P=.05). Results: Mark II and MZ100 specimens fractured at an average load of 216 N and 229 N (survival rate of 17% and 8%), respectively, with no difference in survival probability (P=.18). Among the fractured samples, 40% of the failures were at the abutment level for Mark II and 27% were at the abutment level for MZ100. No exclusive adhesive failures were observed. Conclusions: Type III Mark II and Paradigm MZ100 veneers showed similar fatigue resistance when bonded to custom non‐retentive zirconia implant abutments. The bond was strong enough to induce abutment fractures. MZ100 presented a higher percentage of “friendly” failures, i.e. maintaining the restoration–abutment adhesive interface and the abutment itself intact. To cite this article:
Magne P, Paranhos MPG, Burnett LH Jr, Magne M, Belser UC. Fatigue resistance and failure mode of novel‐design anterior single‐tooth implant restorations: influence of material selection for type III veneers bonded to zirconia abutments.
Clin. Oral Impl. Res. 22 , 2011; 195–200.
doi: 10.1111/j.1600‐0501.2010.02012.x     

Influence of anodized titanium abutments on the esthetics of the peri-implant soft tissue: A clinical study

Statement of problemThe grayish appearance of a titanium abutment discolors the peri-implant soft tissue, especially if the gingiva is thin. Whether an anodized titanium abutment can prevent the discoloration is unclear.PurposeThe purpose of this clinical study was to investigate the color change of peri-implant soft tissue surrounding a titanium abutment that had been colored by anodic oxidation.Material and methodsCommercially available titanium abutments were anodized to form a gold and pink titanium abutment and formed the experimental groups. Unanodized titanium and zirconia abutment were used as the control groups. Four types of abutments were fabricated for each participant who received dental implants in the anterior maxilla. The abutments and corresponding definitive crowns were inserted, and the color of the peri-implant soft tissue and contralateral gingiva were measured with a spectrophotometer. The thickness of the peri-implant soft tissue was recorded after probing with an endodontic file.ResultsEleven participants were included in this study. The color differences caused by all tested abutments were higher than the critical threshold of ΔE=3.7. The mean color difference (ΔE), from low to high, was the zirconia, pink-anodized titanium, gold-anodized titanium, and unanodized titanium abutment; their values of (ΔE) were 6.81, 7.63, 7.90, and 8.74, respectively. The mean thickness of the peri-implant soft tissue was 2.41 ±0.52 mm.ConclusionsWithin the limitation of the small sample size in this study, the gold-anodized and pink-anodized titanium abutment achieved better esthetics for peri-implant soft tissue than the unanodized titanium abutment. Zirconia was the optimal abutment material for the esthetic region.     

In vivo performance of zirconia and titanium implants: a histomorphometric study in mini pig maxillae

Objectives: To compare the bone tissue response to surface‐modified zirconia (ZrO₂) and titanium implants. Methods: Cylindrical low‐pressure injection moulded zirconia (ZrO₂) implants were produced with an acid‐etched surface. Titanium implants with identical shape, sandblasted and acid‐etched surface (SLA) served as controls. Eighteen adult miniature pigs received both implant types in the maxilla 6 months after extraction of the canines and incisors. The animals were euthanized after 4, 8 and 12 weeks and 16 zirconia and 18 titanium implants with the surrounding tissue were retrieved, embedded in methylmethacrylate and stained with Giemsa–Eosin. The stained sections were digitized and histomorphometrically analysed with regard to peri‐implant bone density (bone volume/total volume) and bone–implant contact (BIC) ratio. Statistical analysis was performed using Mann–Whitney' U‐test. Results: Histomorphometrical analysis showed direct osseous integration for both materials. ZrO₂ implants revealed mean peri‐implant bone density values of 60.4% (SD ± 9.9) at 4 weeks, 65.4% (SD ± 13.8) at 8 weeks, and 63.3% (SD ± 21.5) at 12 weeks after implantation, whereas Ti‐SLA implants demonstrated mean values of 61.1% (SD ± 6.2), 63.6% (SD ± 6.8) and 68.2% (SD ± 5.8) at corresponding time intervals. Concerning the BIC ratio, the mean values for ZrO₂ ranged between 67.1% (SD ± 21.1) and 70% (SD ± 14.5) and for Ti‐SLA between 64.7% (SD ± 9.4) and 83.7% (SD ± 10.3). For the two parameters investigated, no significant differences between both types of implants could be detected at any time point. Conclusion: The results indicate that there was no difference in osseointegration between ZrO₂ implants and Ti‐SLA controls regarding peri‐implant bone density and BIC ratio. To cite this article :
Gahlert M, Roehling S, Sprecher CM, Kniha H, Milz S, Bormann K. In vivo performance of zirconia and titanium implants: a histomorphometric study in mini pig maxillae.
Clin. Oral Impl. Res. 23 , 2012; 281–286.
doi: 10.1111/j.1600‐0501.2011.02157.x     

Effects of modified abutment characteristics on peri‐implant soft tissue health: A systematic review and meta‐analysis

Objectives

The purpose of this systematic review was to evaluate the impact of the abutment characteristics on peri‐implant tissue health and to identify the most suitable material and surface characteristics.

Methods

A protocol was developed aimed to answer the following focused question: “Which is the effect of the modification of the abutment design in regard to the maintenance of the peri‐implant soft tissue health?” Further subanalysis aimed to investigate the impact of the abutment material, macroscopic design, surface topography and surface manipulation. Randomised controlled trials (RCTs) with a follow‐up of at least 6 months after implant loading were considered as inclusion criteria. Meta‐analyses were performed whenever possible.

Results

Nineteen final publications from thirteen investigations were included. The results from the meta‐analysis indicated that zirconia abutments (Zi) experienced less increase in BOP values over time [n = 3; WMD = ?26.96; 95% CI (?45.00; ?8.92); p = .003] and less plaque accumulation [n = 1; MD = ?20.00; 95% CI (?41.47; 1.47); p = .068] when compared with titanium abutments (Ti). Bone loss was influenced by the method of abutment decontamination [n = 1; MD = ?0.44; 95% CI (?0.65; ?0.23); p < .001]. The rest of the studied outcomes did not show statistically significant differences.

Conclusions

The macroscopic design, the surface topography and the manipulation of the implant abutment did not have a significant influence on peri‐implant inflammation. In contrast, the abutment material demonstrated increased BOP values over time for Ti when compared to Zi abutments.

     

Randomized-controlled clinical trial of customized zirconia and titanium implant abutments for single-tooth implants in canine and posterior regions: 3-year results

Objectives: The aim was to test whether or not zirconia abutments exhibit the same survival and technical/biological outcome as titanium abutments. Material and methods: Twenty‐two patients receiving 40 single‐tooth implants in canine and posterior regions were included. The implant sites were randomly assigned to 20 zirconia and 20 titanium abutments. All‐ceramic and metal–ceramic crowns were fabricated. At baseline, 6, 12 and 36 months, the reconstructions were examined for technical and biological problems. Probing pocket depth (PPD), plaque control record (PCR) and bleeding on probing (BOP) were assessed at abutments (test) and analogous contralateral teeth (control). Standardized radiographs of the implants were made and the bone level (BL) was measured referring to the implant shoulder on mesial (mBL) and distal sides (dBL). The difference of color (ΔE) of the peri‐implant mucosa and the gingiva of control teeth was assessed with a spectrophotometer. The data were statistically analyzed with Mann–Whitney Rank and Student's unpaired t‐tests. Results: Eighteen patients with 18 zirconia and 10 titanium abutments were examined at a mean follow‐up of 36 months (range 31.5–53.3 months). No fracture of an abutment or loss of a reconstruction was found. Hence, both exhibited 100% survival. At two metal–ceramic crowns supported by titanium abutments chipping of the veneering ceramic occurred. No difference of the biological outcome of zirconia and titanium abutments was observed: PPD ( 3.2 ± 1 mm, mPPD_Ti 3.4 ± 0.5 mm), PCR ( 0.1 ± 0.2, mPCR_Ti 0.1 ± 0.2) and BOP ( 0.4 ± 0.4, mBOP_Ti 0.2 ± 0.3). Furthermore, the BL was similar at implants supporting zirconia and titanium abutments ( 1.7 ± 1, 1.6 ± 1; mBL_Ti 2 ± 1, dBL_Ti 2.1 ± 1). Both, zirconia and titanium abutments induced a similar amount of discoloration of the mucosa compared with the gingiva at natural teeth ( 9.3 ± 3.8, ΔE_Ti 6.8 ± 3.8). Conclusions: At 3 years, zirconia and titanium abutments exhibited same survival and technical, biological and esthetical outcomes.     

Dimensional profile of oral mucosa around combined tooth-implant-supported bridgework in macaque mandible

Purpose: A stable oral mucosa is crucial for long‐term survival and biofunctionality of implants. Most of this evidence is derived from clinical and animal studies based solely on implant‐supported prosthesis. Much less is known about the dimensions and relationships of this soft tissue complex investing tooth‐implant‐supported bridgework (TISB). The aim here was to obtain experimental evidence on the dimensional characteristics of oral mucosa around TISB with two different abutment designs. Methods: Sixteen 3‐unit TISB were constructed bilaterally in the mandible of eight adult Macaca fascicularis. An implant system with a standard progressive thread design was the bone‐anchoring implant in the second mandibular molar region while the second mandibular premolar served as the natural tooth abutment. Eight implants were connected with the tapered abutment, the remaining with butt‐joint abutment, in a split‐mouth design. These were allowed to functional load for 6 months before sacrification for histomorphometry. Six soft tissue indices were scored: coronal gingival mucosa‐to‐implant top distance (DIM); sulcus depth (SD); junctional epithelium (JE); connective tissue contact (CTC); implant top to first bone‐to‐implant contact distance (DIB); and biologic width (BW=SD+JE+CTC); corresponding parameters in the natural tooth abutment were also measured. Results: Mucosal dimensions in tapered implants (^*BW=3.33±0.43; SD=1.03±0.24; JE=1.08±0.13; CTC=1.22±0.23 mm) were comparable with those of natural tooth abutments (BW=3.04±0.18; SD=0.93±0.1; JE=0.78±0.1; Attachment=1.33±0.09 mm), but differed from butt‐joint implants (^*BW=4.88±1.24; SD=1.47±0.38; JE=1.49±0.4; CTC=1.92±0.93 mm) (^*P<0.05). Conclusions: Results suggested that soft tissue dimensions around TISB are influenced by the implant–abutment interface and abutment material used. Mucosa investing tapered abutment tends to recapitulate soft tissue physiologic dimensions of natural tooth. To cite this article:
Siar CH, Toh CG, Ali TBT, Seiz D, Ong ST. Dimensional profile of oral mucosa around combined tooth‐implant‐supported bridgework in macaque mandible.
Clin. Oral Impl. Res. 23 , 2012 438–446.
doi: 10.1111/j.1600‐0501.2010.02145.x     

A 4-Year Prospective Study to Assess Peri-Implant Hard and Soft Tissues Adjacent to Titanium Versus Gold-Alloy Abutments in Cemented Single Implant Crowns

PURPOSE: The purpose of this prospective clinical study was to compare titanium and gold-alloy abutments when used with cemented, implant-supported single-tooth crowns. For 4 years following prosthodontic rehabilitation, these abutments were evaluated with respect to peri-implant marginal bone levels and peri-implant soft tissue parameters. MATERIALS AND METHODS: During the years 1998 to 2000, 20 patients were selected from a patient population receiving treatment in the Implantology Department at the University of Padova, Italy. They all presented with single-tooth bilateral edentulous sites in the premolar/molar region with adequate bone width, similar bone height on each side, and an occlusal scheme that allowed for the establishment of identical occlusal cusp/fossa contacts on each side. Each subject received two identical implants (one in each edentulous site). One was randomly selected to be restored with a titanium abutment and a cemented implant-supported single-tooth crown, and the other was restored with a gold-alloy abutment and a cemented implant-supported single tooth crown. Data on peri-implant marginal bone levels and soft tissue parameters were collected for 4 years after abutment and crown insertion placement and analyzed to determine whether there was a significant (p< .001) difference with respect to the type of abutments (titanium vs. gold alloy) used. RESULTS: All subjects completed the study. All 40 implants survived, resulting in a cumulative implant success rate of 100%. Statistical analysis revealed no significant differences between the two groups with respect to peri-implant marginal bone levels and soft tissue parameters. CONCLUSIONS: Within the limitations of this study, the results indicate that there was no evidence of different response with the peri-implant marginal bone and soft tissue when titanium or gold-alloy abutments were used in conjunction with the cemented, single-tooth implant restorations provided for this limited patient population. There was no evidence of different behavior of peri-implant marginal bone and of peri-implant soft tissue when titanium abutments or gold-alloy abutments were used for cemented single-tooth implant restorations in this limited patient population.     

Tissue alterations at implant-supported single-tooth replacements: a 1-year prospective clinical study

Objectives: The aim of this prospective study was to evaluate dimensional alterations of the peri‐implant tissues at single‐tooth restorations from the time of implant placement to 1‐year post‐loading. Material and methods: Eleven patients, aged 18–36 years, subjected to single‐tooth replacements with implant‐supported restorations (Brånemark implant^® system) in the maxillary anterior region were included in the analysis. The implant installation was performed as a two‐stage procedure with a 6‐month healing interval. Bone dimensions were determined by direct assessments immediately following implant placement and at abutment connection. The prosthetic restoration was placed approximately 1 month after abutment surgery. Radiographic and clinical examinations were performed at crown placement and at 1‐year post‐loading. Assessments of the soft tissues at the implant site and at the neighboring teeth were performed before and during implant placement, before abutment connection, after crown placement and at the 1‐year follow‐up examination. Mean values and standard deviations were calculated for each variable and interval, with the subject as the statistical unit. Results: At the time of abutment connection, a mean loss of bone height at the facial and lingual aspect of the implant amounting to 0.7–1.3 mm (P<0.05) was recorded, whereas no significant change was noted at proximal sites. A mean reduction of 0.4 mm of the labial bone thickness was observed between implant placement and the second‐stage surgery. The radiographic bone‐to‐implant level showed a mean loss of 0.9 mm between abutment connection and crown placement (P<0.05) and a further 0.7 mm loss at 1 year (P<0.05). The thickness of the labial mucosa was increased at crown placement followed by a slight remission at 1 year. During the corresponding interval, a mean apical displacement of the labial soft tissue margin of 0.6 mm had taken place (P<0.05). A papilla fill of ≥50% was observed at a frequency of 32% at crown placement and 86% at 1 year. Conclusions: The results demonstrated that following implant surgery remodeling takes place, which is manifested in diminished bone dimensions, both horizontally and vertically, at the facial aspect of the implant. The observed soft tissue alterations after the crown placement may affect the esthetic appeal of the restorative therapy.     

Prefabricated zirconium dioxide implant abutments for single‐tooth replacement in the posterior region: evaluation of peri‐implant tissues and superstructures after 12 months of function

Aim: In the present study, prefabricated abutments made of zirconium dioxide Y‐TZP (tetragonal zirconia polycrystals) were inserted into the posterior region under controlled clinical conditions. The aim was to test whether abutments made of zirconium dioxide are suitable for this indication. Investigation parameters included reactions of peri‐implant tissue and the structural integrity of the all‐ceramic superstructures on the implants. Results after 12 months in function are reported in this article. Material and methods: Forty implants of the XiVE^® S plus screw‐type implants (DENTSPLY Friadent) were inserted into the posterior region of 24 patients. After the healing period, the implants were provided with all‐ceramic abutments made of zirconium dioxide Y‐TZP (FRIADENT^® CERCON^® Abutment; DENTSPLY Friadent). All‐ceramic crowns (CERCON^® smart ceramics; DENTSPLY DeguDent) were used as superstructures and cemented using the conventional method. The following parameters were used to document the state of soft tissue: modified plaque index (mPI), sulcus fluid flow rate (SFFR, Periotron; Oraflow Inc), modified sulcus bleeding index (mSBI) and pocket depth (ST). Mesial and distal bone levels were determined on radiographs during the prosthetic treatment and at the 12‐month recall. The Periotest^? (Medizintechnik Gulden) was used to determine implant stability. Results: All implants could be followed up after 12 months in function. In the presence of good oral hygiene (mPI: 0.5), the parameters SFFR (18) and mSBI (0.5) were indicative of stable and healthy soft tissue. ST was highest at the distal points of measurement (2.3 mm) and was generally at a low level. Compared with the baseline situation, proximal bone defects were reduced from ?1.1 to ?1 mm during the 12‐month period of functioning. The mean Periost^? values at the 12‐month recall were ?1.9 in the maxilla and ?3.8 in the mandible. Neither implant loss nor crown fractures occurred. Chipping of parts of the veneering ceramic was registered in four cases (10%). Conclusion: After 12 months of wear, no mechanical failure was registered in any of the all‐ceramic abutments. On clinical investigation, the peri‐implant hard and soft tissues were largely healthy and devoid of inflammation. To cite this article:
Nothdurft F, Pospiech P. Prefabricated zirconium dioxide implant abutments for single‐tooth replacement in the posterior region: evaluation of peri‐implant tissues and superstructures after 12 months of function.
Clin. Oral Impl. Res. 21 , 2010; 857–865.
doi: 10.1111/j.1600‐0501.2009.01899.x     

Peri‐implant soft tissue and bone crest alterations at fixed dental prostheses: a 3‐year prospective study

Objectives: The aim of this 3‐year prospective study involving patients receiving implant‐supported fixed dental prostheses (FDPs) was to longitudinally evaluate soft and hard tissue alterations from the time of implant placement. Material and methods: Sixteen subjects with 18 implant‐supported FDPs on 43 implants were included in the study. Peri‐implant soft and hard tissue assessments were performed at implant placement, 2, 6, 12, 24 and 36 months. Variables describing the peri‐implant soft tissue conditions and topography were assessed by clinical, photographic and study model assessments. Variables of implant position and bone topography were measured in radiographs taken at each examination interval. Multilevel regression models were formulated to identify factors of significance for proximal bone crest alterations and proximal soft tissue height. Results: During the first 6 months after the one‐stage implant placement surgery, the soft tissue margin receded about 0.6 mm at facial implant sites, while a mean increase was observed at tooth‐facing proximal sites (1.1 mm) and no change at inter‐implant sites. Loss in proximal bone crest height was more pronounced at inter‐implant than tooth–implant units at 6 months (0.6 vs. 0.1 mm). Between 6 and 36 months, no further significant soft or hard tissue changes were observed. Multilevel regression analysis revealed that the proximal bone crest level significantly influenced the proximal soft tissue height assessed from the implant/abutment level. Significant predictors for loss in proximal bone crest level over the 3 years were horizontal inter‐unit distance, type of proximal unit (tooth/implant or inter‐implant) and peri‐implant bone‐level change. Conclusions: Soft and hard tissue changes around implant‐supported FDPs took place primarily during the first 6 months after the one‐stage implant installation surgery. The pattern of tissue alterations during the follow‐up differed between tooth–implant and inter‐implant proximal sites. To cite this article:
Chang M, Wennström JL. Peri‐implant soft tissue and bone crest alterations at fixed dental prostheses: a 3‐year prospective study.
Clin. Oral Impl. Res. 21, 2010; 527–534.
doi: 10.1111/j.1600‐0501.2009.01874.x     

The Peri‐Implant Sulcus Compared with Internal Implant and Suprastructure Components: A Microbiological Analysis

Purpose: A recent in vivo study has shown considerable contamination of internal implant and suprastructure components with great biodiversity, indicating bacterial leakage along the implant‐abutment interface, abutment‐prosthesis interface, and restorative margins. The goal of the present study was to compare microbiologically the peri‐implant sulcus to these internal components on implants with no clinical signs of peri‐implantitis and in function for many years. Checkerboard DNA‐DNA hybridization was used to identify and quantify 40 species. Material and Methods: Fifty‐eight turned titanium Brånemark implants in eight systemically healthy patients (seven women, one man) under regular supportive care were examined. All implants had been placed in the maxilla and loaded with a screw‐retained full‐arch bridge for an average of 9.6 years. Gingival fluid samples were collected from the deepest sulcus per implant for microbiological analysis. As all fixed restorations were removed, the cotton pellet enclosed in the intra‐coronal compartment and the abutment screw were retrieved and microbiologically evaluated. Results: The pellet enclosed in the suprastructure was very similar to the peri‐implant sulcus in terms of bacterial detection frequencies and levels for practically all the species included in the panel. Yet, there was virtually no microbial link between these compartments. When comparing the abutment screw to the peri‐implant sulcus, the majority of the species were less frequently found, and in lower numbers at the former. However, a relevant link in counts for a lot of bacteria was described between these compartments. Even though all implants in the present study showed no clinical signs of peri‐implantitis, the high prevalence of numerous species associated with pathology was striking. Conclusions: Intra‐coronal compartments of screw‐retained fixed restorations were heavily contaminated. The restorative margin may have been the principal pathway for bacterial leakage. Contamination of abutment screws most likely occurred from the peri‐implant sulcus via the implant‐abutment interface and abutment‐prosthesis interface.     

Prosthodontic considerations designed to optimize outcomes for single-tooth implants. A review of the literature

Background: The aim of this study was to review the literature on the restoration of single‐tooth implants, and to develop evidence‐based conclusions to optimize aesthetic, biologic and patient‐related outcomes. Methods: An electronic and hand search was conducted using the search terms ‘dental implants, single‐tooth; dental restoration, temporary; dental impression materials; dental impression technique; dental prosthesis, implant‐supported; dental prosthesis design; dental abutments; dental occlusion; maintenance; survival; and survival analysis’. Resultant titles were screened, and full text was obtained where relevant. The authors selected the most appropriate articles, giving preference to systematic reviews and long‐term, patient‐based outcome data. Results: Thirty‐nine articles were selected and critiqued by the authors. Conclusions: There was strong suggestion by several authors that peri‐implant soft tissue aesthetics can be sculpted through provisional restoration contour, but there are no clinical outcome studies to define or support this claim. Laboratory studies demonstrate that pick‐up type impression copings in conjunction with elastomeric impressions are the most accurate means for transferring implant position to a dental cast. Laboratory and finite‐element analysis studies suggest implants with an internal‐type connection show improved stress distribution, but supportive clinical data are lacking. The authors of this review favour a screw‐retained prosthesis for retrievability. Clinical and histological studies show that gold, titanium and zirconia ceramic abutment materials exhibit excellent biological responses, although there is insufficient data on the clinical service provided by zirconia as an implant‐substructure material. The literature does not associate any particular occlusal scheme with superior clinical outcomes. Implant‐borne single crowns offer comparable clinical service to tooth‐borne fixed dental prostheses. However, single‐tooth implant restorations are associated with an increased incidence of biological and technical complications.     

Influence of abutment material on the fracture strength and failure modes of abutment‐fixture assemblies when loaded in a bio‐faithful simulation

Objectives: The aim of the present study was to evaluate differences in the ultimate fracture resistance of titanium and zirconia abutments. Material and methods: Twenty titanium fixtures were embedded in 20 resin mandible section simulators to mimic osseointegrated implants in the premolar area. The embedded implants were then randomly divided into two groups. Afterwards, specimens in group A (n=10) were connected to titanium abutments (TiDesign^? 3.5/4.0, 5.5, 1.5 mm), while specimens in group B (n=10) were connected to zirconia abutments (ZirDesign^? 3.5/4.0, 5.5, 1.5 mm). Both groups were loaded to failure in a dynamometric testing machine. Fractured samples were then analyzed by scanning electron microscopy (SEM). Results: Group A showed a significantly higher fracture strength than that observed in group B. Group A failures were observed at the screw that connects the abutment with the implant while the abutment connection hexagons were plastically bent by the applied load. Group B failures were a result of abutment fractures. SEM analysis showed that in group A the screw failure was driven by crack nucleation, coalescence and propagation, while in group B, the SEM analysis of failed surfaces showed the conchoidal fracture profile characteristic of brittle materials. Conclusions: The strength of both tested systems is adequate to resist physiologic chewing forces in the premolar area. Conversely, the titanium and zirconia failure modes evaluated here occurred at unphysiological loads. In addition, because the abutments were tested witout crowns, the presented data have limited direct transfer to the clinical situation. To cite this article:
Apicella D, Veltri M, Balleri P, Apicella A, Ferrari M. Influence of abutment material on fracture strength and failure modes of abutment‐fixture assemblies when loaded in a bio‐faithful simulation.
Clin. Oral Impl. Res. 22 , 2011; 182–188.
doi: 10.1111/j.1600‐0501.2010.01979.x