Tissue integration of a new titanium-zirconium dental implant: a comparative histologic and radiographic study in the canine

Background: This study evaluates a newly developed titanium–zirconium implant (TiZr), comparing it to a commercially available pure titanium (Ti) implant subjected to the same surface treatment. Methods: In nine dogs, 12 implants (six TiZr and six Ti) were randomly placed in the mandible with the implant shoulder at the bone crest and subjected to submerged healing. Standardized radiographs were taken after implantation, and at the sacrifice of 2 weeks (three dogs), 4 weeks (three dogs), and 8 weeks (three dogs). Histologic and histomorphometric measurements were performed on non‐decalcified histologic sections. The main outcome measures included the first bone–implant contact (fBIC) and BIC over time. For statistical analysis, Wilcoxon signed‐rank test and mixed model regressions were applied. Results: From baseline to 8 weeks, a mean bone loss of 0.09 ± 0.33 mm for TiZr and a gain of 0.02 ± 0.33 mm for Ti were calculated radiographically. The number of implants with the fBIC coronal to the reference point (implant shoulder) gradually increased over time, reaching 39% of all TiZr implants and 50% of all Ti implants at 8 weeks. The mean fBIC values for Ti and TiZr were 0.29 ± 0.42 mm and 0.26 ± 0.32 mm (2 weeks), ?0.01 ± 0.20 mm and 0.10 ± 0.28 mm (4 weeks), and ?0.06 ± 0.22 mm and 0.08 ± 0.30 mm (8 weeks), respectively. The mean BIC values peaked at 86.9% ± 6.8% (8 weeks) for TiZr and at 83.4% ± 5.9% (4 weeks) for Ti. No statistically significant differences were observed at any time point. Conclusion: TiZr and Ti bone level implants with chemically‐modified, sandblasted, and acid‐etched surfaces performed similarly in regards to osseointegration in this unloaded canine study.     

A Double-Blind Randomized Controlled Trial (RCT) of Titanium-13Zirconium versus Titanium Grade IV Small-Diameter Bone Level Implants in Edentulous Mandibles - Results from a 1-Year Observation Period

Background: The use of endosseous dental implants has become common practice for the rehabilitation of edentulous patients, and a two‐implant overdenture has been recommended as the standard of care. The use of small‐diameter implants may extend treatment options and reduce the necessity for bone augmentation. However, the mechanical strength of titanium is limited, so titanium alloys with greater tensile and fatigue strength may be preferable. Purpose: This randomized, controlled, double‐blind, multicenter study investigated in a split‐mouth model whether small‐diameter implants made from Titanium‐13Zirconium alloy (TiZr, Roxolid?) perform at least as well as Titanium Grade IV implants. Methods and Materials: Patients with an edentulous mandible received one TiZr and one Ti Grade IV small‐diameter bone level implant (3.3 mm, SLActive®) in the interforaminal region. The site distribution was randomized and double‐blinded. Outcome measures included change in radiological peri‐implant bone level from surgery to 12 months post‐insertion (primary), implant survival, success, soft tissue conditions, and safety (secondary). Results: Of 91 treated patients, 87 were available for the 12‐month follow‐up. Peri‐implant bone level change (?0.3 ± 0.5 mm vs ?0.3 ± 0.6 mm), plaque, and sulcus bleeding indices were not significantly different between TiZr and Ti Grade IV implants. Implant survival rates were 98.9 percent and 97.8 percent, success rates were 96.6 percent and 94.4 percent, respectively. Nineteen minor and no serious adverse events were related to the study devices. Conclusion: This study confirms that TiZr small‐diameter bone level implants provide at least the same outcomes after 12 months as Ti Grade IV bone level implants. The improved mechanical properties of TiZr implants may extend implant therapy to more challenging clinical situations.     

Evaluation of a New Titanium‐Zirconium Dental Implant: A Biomechanical and Histological Comparative Study in the Mini Pig

Background: Titanium zirconium alloy with 13–17% zirconium (TiZr1317) shows significantly better mechanical attributes than pure Ti with respect to elongation and fatigue strength. This material may be suitable for thin implants and implant components exposed to high mechanical constraints. Purpose: The aim of this study was to test the hypothesis that TiZr1317 and Ti implants show comparable osseointegration and stability. Materials and Methods: The mandibular premolars (P1, P2, P3) and the first molar (M1) in 12 adult miniature pigs were extracted 3 months prior to the study. Six specially designed implants made from Ti (commercially pure, Grade 4) or TiZr1317 (Roxolid®, Institut Straumann AG, Basel, Switzerland) with a hydrophilic sandblasted and acid‐etched (SLActive, Institut Straumann AG, Basel, Switzerland) surface were placed in each mandible; three standard implants modified for evaluation of removal torque (RT) in one side and three bone‐chamber implants for histologic observations in the contralateral side. RT tests were performed after 4 weeks when also the bone chamber implants and surrounding tissue were biopsied for histologic analyses in ground sections. Results: The RT results indicated significantly higher stability (p = 0.013) for TiZr1317 (230.9 ± 22.4 Ncm) than for Ti implants (204.7 ± 24.0 Ncm). The histology showed similar osteoconductive properties for both implant types. Histomorphometric measurements showed a statistically significant higher (p = 0.023) bone area within the chamber for the TiZr1317 implants (45.5 ± 13.2%) than did the Ti implants (40.2 ± 15.2%). No difference was observed concerning the bone to implant contact between the groups with 72.3 ± 20.5% for Ti and 70.2 ± 17.3% for TiZr1317 implants. Conclusion: It is concluded that the TiZr1317 implant with a hydrophilic sandblasted and acid‐etched surface showed similar or even stronger bone tissue responses than the Ti control implant     

Peripheral quantitative computer tomographic,histomorphometric, and removal torque analyses of two different non‐coated implants in a rabbit model

Objective: The objectives of this study were (1) to investigate the bone–tissue response to zirconia and titanium implants at the implant‐to‐bone interface and at the periosteal level and (2) to quantitatively measure the mineral density of the peri‐implant bone using peripheral quantitative computer tomography (pQCT). Material and methods: Ten 3.5 mm × 6.6 mm screw‐shaped threaded implants fabricated from titanium and zirconia were inserted into the mid‐tibial diaphysis of five male New Zealand white rabbits. Calcein green was administered at 4 weeks post‐implantation. The animals were sacrificed after 6 weeks and implants were retrieved and analyzed in terms of bone‐to‐implant contact (BIC), bone area (BA), mineralized surface (MS) percentage, inter‐thread calcein labels, removal torque (RT) values, as well as pQCT measurements. Findings: No statistically significant differences were detected between the zirconia and titanium implants in terms of BIC, RT, and pQCT. However, statistically significant higher BA and MS levels were found in the titanium group, while the higher amount of calcein labels occupying the threads were found in the zirconium group. Significant differences were also found in the quantity and the composition of bone at the bone–implant interfacial area vs. the region 1.5 mm away from the bone–implant interface, irrespective of the implant type. Conclusion: Zirconia implants demonstrated a lower bone remodeling activity in the periosteal region. The bone at the bone–implant interface shows a significantly lower cortical bone density, a higher trabecular density, and trabecular mineral content. Finally, zirconia and titanium implants showed similar bone–implant responses in terms of BIC and RT. To cite this article:
Shin D, Blanchard SB, Ito M, Chu T‐MG. Peripheral quantitative computer tomographic, histomorphometric, and removal torque analyses of two different non‐coated implants in a rabbit model.
Clin. Oral Impl. Res. 22 , 2011; 242–250.
doi: 10.1111/j.1600‐0501.2010.01980.x     

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     

Histological and histomorphometric evaluation of immediate implant placement on a dog model with a new implant surface treatment

Purpose: The aim of this study was to evaluate crestal bone resorption and bone apposition resulting from immediate post‐extraction implants in the canine mandible, comparing a conditioned sandblasted acid‐etched implant surface with a non‐conditioned standard sandblasted implant surface. Material and methods: In this experimental study, third and fourth premolars and distal roots of first molars were extracted bilaterally from six Beagle dog mandibles. Each side of the mandible received three assigned dental implants, with the conditioned surface (CS) on the right side and the non‐conditioned surface (NCS) on the left. The dogs were sacrificed at 2 (n=2), 4 (n=2) and 12 weeks (n=2) after implant placement. Results: The microscopic healing patterns at 2, 4 and 12 weeks for both implant types (CS and NCS) yielded similar qualitative bone findings. The mean crestal bone resorption was found to be greater for all implants with NCS (2.28±1.9 mm) than CS (1.21±1.05 mm) at 12 weeks. The mean percentage of newly formed bone in contact with implants was greater in implants CS (44.67±0.19%) than with the NCS (36,6±0.11%). There was less bone resorption with the CS than the NCS. Conclusion: The data show significantly more bone apposition (8% more) and less crestal bone resorption (1.07 mm) with the CS than with the NCS after 12 weeks of healing. This CS can reduce the healing period and increase bone apposition in immediate implant placements. To cite this article:
Calvo‐Guirado JL, Ortiz‐Ruiz AJ, Negri B, López‐Marí L, Rodriguez‐Barba C, Schlottig F. Histological and histomorphometric evaluation of immediate implant placement on a dog model with a new implant surface treatment.
Clin. Oral Impl. Res. 21 , 2010; 308–315.
doi: 10.1111/j.1600‐0501.2009.01841.x     

One-year clinical and radiographic assessment of fluoride-enhanced implants on immediate non-functional loading in posterior maxilla and mandible: a pilot prospective clinical series study

Objective: The functional, esthetic, and psychological problems of 3–6 months of edentulousness and also discomfort of two‐stage surgery might cause many patients to avoid implant‐supported restorations. Therefore, the immediate non‐functional loading protocol might be of value. Methods: Twenty Astra Tech implants, 11–13 mm in length and 3.5–4 mm in diameter, were placed in maxillary and mandibular posterior sites of 10 healthy patients (two for each) with adequate alveolar bone. Temporary prostheses were relieved of all centric and eccentric contacts. Functional permanent prostheses were fabricated 13 weeks postoperatively. Clinical and radiographic examinations (including the implant stability quotient [ISQ]) were carried out immediately after implantation and 3, 6, and 12 months postoperatively. Results: A 100% success rate was observed within 1 year. The plaque and bleeding indices, and pocket‐probing depths did not show a significant change throughout the study. The ISQ values after implant insertion, and 3, 6, and 12 months later were respectively 76.6 ± 6.57, 77.6 ± 10.54, 81.8 ± 6.8, and 82.43 ± 3.7. The increase was statistically significant (P=0.004) according to the Freidman test. The ISQ values measured after the implant insertion were significantly different from those measured in the sixth and 12th postoperative months (P<0.008) according to the Wilcoxon signed‐ranks test. The mean crestal alveolar bone resorption values in the third, sixth, and 12th postoperative months were 0.4 ± 0.55, 0.48 ± 0.37, and 0.48 ± 0.21 mm, respectively; and the change in marginal alveolar bone loss was not significant according to the Freidman test. Conclusion: Within the limitations of this pilot study, non‐functional immediate loading might meet the expectations of both the patients and clinicians. To cite this article:
Rismanchian M, Fazel A, Rakhshan V, Eblaghian G. One‐year clinical and radiographic assessment of fluoride‐enhanced implants on immediate non‐functional loading in posterior maxilla and mandible: a pilot prospective clinical series study.
Clin. Oral Impl. Res. xx , 2011; 000–000.
doi: 10.1111/j.1600‐0501.2010.02134.x     

Transmucosal healing around peri‐implant defects: crestal and subcrestal implant placement in dogs

Objective: This study was designed to evaluate the transmucosal healing response of implants placed with the junction of the smooth surfaces, either crestal or subcrestal, into simulated extraction defects after healing periods of 1 and 3 months. Materials and methods: A total of 23 Straumann SP ?3.3 mm NN, SLA^® 10 mm implants were placed in the mandibular premolar regions of three greyhound dogs 3 months after the teeth were removed. Five control implants were placed at the crestal bone level, and test implants with surgically created peri‐implant defects of 1.25 mm wide × 5 mm depth were placed either at the crestal (nine implants) or at the 2 mm subcrestal (nine implants) bone level. Implants on the right side were placed 1 month before the dogs were sacrificed, and implants on the left side were placed 3 months before sacrifice. All dogs had daily plaque control following surgery and were sacrificed 3 months after implant placement for histological and histometric analyses. Results: Mesial–distal ground sections of the control and test implant specimens showed a greater %BIC in the coronal defect region after 3 months of healing. This healing response was incomplete for the test implants compared with the control implants after a 1‐month healing period. The histometric measurements for test implants placed at the crestal bone level or 2 mm subcrestal with surgically created peri‐implant defects were more coronal or closer to the implant margin compared with the control implants. Additionally, the degree of osseointegration between the newly formed bone and the implant surface was similar between the test implants. Conclusion: Peri‐implant defects of 1.25 mm width healed with spontaneous bone regeneration around implants placed transmucosally at crestal or 2 mm subcrestal with a high degree of osseointegration after a 3‐month healing period. To cite this article:
Tran BLT, Chen ST, Caiafa A, Davies HMS, Darby IB. Transmucosal healing around peri‐implant defects: crestal and subcrestal implant placement in dogs.
Clin. Oral Impl. Res. 21 , 2010; 794–803.
doi: 10.1111/j.1600‐0501.2010.01911.x     

Peri-implant bone reactions to immediate implants placed at different levels in relation to crestal bone. Part I: a pilot study in dogs

Purpose: The aim of the present study was to evaluate bone remodeling and bone‐to‐implant contact (BIC) after immediate placement at different levels in relation to the crestal bone of Beagle dogs. Materials and methods: The mandibular bilateral second, third and fourth premolars of six Beagle dogs were extracted and six implants were immediately placed in the hemi‐arches of each dog. Randomly, three cylindrical and three tapered implants were inserted crestally (control group) and 2 mm subcrestally (experimental group). Both groups were treated with a minimal mucoperiosteal flap elevation approach. A gap from the buccal cortical wall to the implant was always left. Three dogs were allowed a 4‐week submerged healing period and the other three an 8‐week submerged healing period. The animals were sacrificed and biopsies were obtained. Biopsies were processed for ground sectioning. Histomorphometric analysis was carried out in order to compare buccal and lingual bone height loss, and BIC between the two groups. Results: All implants osseointegrated clinically and histologically. Healing patterns examined microscopically at 4 and 8 weeks for both groups (crestal and subcrestal) yielded similar qualitative bone findings. The distance from the top of the implant collar to the first BIC in the lingual crest (A–Lc) showed a significant difference (P=0.0313): 1.91 ± 0.2 mm in the control group and 1.08 ± 0.2 mm in the experimental group. There was less bone resorption in subcrestal implants than crestal implants. The mean percentage of newly formed BIC was greater with the cylindrical implant design (46.06 ± 4.09%) than with the tapered design (32.64 ± 3.72%). Conclusion: These findings suggest that apical positioning of the top of the implant does not jeopardize bone crest and peri‐implant tissue remodeling. However, less resorption of the Lc may be expected when implants are placed 2 mm subcrestally. To cite this article:
Negri B, Calvo‐Guirado JL, Pardo‐Zamora G, Ramírez‐Fernández MP, Delgado‐Ruíz RA, Muñoz‐Guzón F. Peri‐implant bone reactions to immediate implants placed at different levels in relation to crestal bone. Part I: a pilot study in dogs.
Clin. Oral Impl. Res. 23 , 2012; 228–235.
doi: 10.1111/j.1600‐0501.2011.02158.x     

Early loading of single crowns supported by 6‐mm‐long implants with a moderately rough surface: a prospective 2‐year follow‐up cohort study

Aim: To evaluate prospectively the clinical and radiographic outcomes after 2 years of loading of 6 mm long moderately rough implants supporting single crowns in the posterior regions. Material and methods: Forty SLActive Straumann^® short (6 mm) implants were placed in 35 consecutively treated patients. Nineteen implants, 4.1 mm in diameter, and 21 implants, 4.8 mm in diameter, were installed. Implants were loaded after 6 weeks of healing. Implant survival rate, marginal bone loss and resonance frequency analysis (RFA) were evaluated at different intervals. The clinical crown/implant ratio was also calculated. Results: Two out of 40 implants were lost before loading. Hence, the survival rate before loading was 95%. No further technical or biological complications were encountered during the 2‐year follow‐up. The mean marginal bone loss before loading was 0.34±0.38 mm. After loading, the mean marginal bone loss was 0.23±0.33 and 0.21±0.39 mm at the 1‐ and 2‐year follow‐ups. The RFA values increased between insertion (70.2±9) and the 6‐week evaluation (74.8±6.1). The clinical crown/implant ratio increased with time from 1.5 at the delivery of the prosthesis to 1.8 after 2 years of loading. Conclusion: Short implants (6 mm) with a moderately rough surface loaded early (after 6 weeks) during healing yielded high implant survival rates and moderate loss of bone after 2 years of loading. Longer observation periods are needed to draw more definite conclusions on the reliability of short implants supporting single crowns. To cite this article:
Rossi F, Ricci E, Marchetti C, Lang NP, Botticelli D. Early loading of single crowns supported by 6‐mm‐long implants with a moderately rough surface: a prospective 2‐year follow‐up cohort study.
Clin. Oral Impl. Res. 21 , 2010; 937–943.
doi: 10.1111/j.1600‐0501.2010.01942.x     

Osseointegration and stability of a modified sand-blasted acid-etched implant: an experimental pilot study in sheep

Objective: The aim of this pilot study was to compare the early‐term osseointegration characteristics of standard (SLA) and modified sand‐blasted and acid‐etched (modSLA) implants in an experimental animal model. Material and methods: A total of 30 SLA and modSLA implants were placed to the tibiae of three sheep and the insertion torque value (ITV) and resonance frequency analysis (RFA) measurements were performed. RFA measurement was repeated on 3 and 6 weeks healed implants after which the animals were sacrificed for histomorphometric analysis. Bone‐to‐implant contact was assessed on the non‐decalcified sections. Six weeks healed implants were also subjected to the reverse torque test (RTT). Results were analyzed by the Friedman test, Kruskal–Wallis test and Spearman rank correlation test. Results: All implants reached to a strong primary stability with a mean 36.13 ± 2.47 and 35.47 ± 2.85 N/cm ITV. In the surgical stage, RFA values for SLA and modSLA implants were found to be 72.27 ± 3.17 and 71.6 ± 2.87, respectively. After 3 weeks of healing, mean BIC% (80.64 ± 13.89%) and RFA value (76.8 ± 1.14) of modSLA implants were significantly higher (P=0.0002) than that of SLA implants (64.39 ± 21.2 BIC% and 74.2 ± 4.76 RFA). However, no statistically significant difference between SLA and modSLA implants was recorded after 6 weeks of healing. Both implants revealed similar results in the RTT test (115.2 ± 4.14 and 117 ± 4.47 N/cm for SLA and modSLA implants, respectively). No correlation was found between RFA and BIC%. Conclusion: Within the limits of this pilot study, it can be concluded that modSLA implants achieve a higher bone contact and stability at earlier time points when compared with SLA implants. To cite this article:
Abdel‐Haq J, Karabuda CZ, Arιsan V, Mutlu Z, Kürkçü M. Osseointegration and stability of a modified sand‐blasted acid‐etched implant: an experimental pilot study in sheep.
Clin. Oral Impl. Res. 22 , 2011; 265–274.
doi: 10.1111/j.1600‐0501.2010.01990.x     

Long-term follow-up of turned single implants placed in periodontally healthy patients after 16-22 years: radiographic and peri-implant outcome

Objectives: Retrospectively evaluate the survival, radiographic and peri‐implant outcome of single turned Brånemark^? implants after at least 16 years. Materials and methods: From 134 patients (C‐group), 101 could be contacted concerning implant survival and 50 (59 remaining implants) were clinically examined (I‐group). Marginal bone level was radiographically measured from the implant–abutment junction at baseline (=within 6 months after abutment connection) and 1–4, 5–8 and 16–22 years post‐operatively. Probing depth, gingival and plaque index were measured. Marginal bone‐level changes were analyzed using Friedman's and Wilcoxon's signed ranks tests. Spearman's correlations between radiographic and clinical parameters were calculated. Results: In the C‐group, 13 out of 166 implants in 11 out of 134 patients failed (CSR=91.5%). In the I‐group (28 males–22 females; mean age 23.9 years at baseline; range 14–57), the mean follow‐up was 18.4 years (range 16–22). The mean bone level was 1.7±0.88 mm (range ?0.8 to 5) after 16–22 years. Changes in the mean marginal bone level were statistically significant between baseline and the second measuring interval (1–4 years). Thereafter, no significant differences could be demonstrated. The mean interproximal probing depth, gingival and plaque indices were 3.9±1.27 mm, 1.2±0.81 and 0.2±0.48, respectively. Probing depth was moderately correlated with gingival inflammation (r=0.6; P<0.001) but not with bone level (P>0.05). 81.4% of the implants had a bone level ≤2nd thread and 91.5% had a probing depth ≤5 mm. 76.3% had both bone level ≤2nd thread and probing depth ≤5 mm. Conclusions and clinical implications: The single turned Brånemark^? implant is a predictable solution with high clinical survival and success rates. In general, a steady‐state bone level can be expected over decades, with minimal signs of peri‐implant disease. A minority (5%), however, presents with progressive bone loss. To cite this article :
Dierens M, Vandeweghe S, Kisch J, Nilner K, De Bruyn H. Long‐term follow‐up of turned single implants placed in periodontally healthy patients after 16–22 years: radiographic and peri‐implant outcome.
Clin. Oral Impl. Res. 23 , 2012; 197–204. doi: 10.1111/j.1600‐0501.2011.02212.x     

The use of autologous venous blood for maxillary sinus floor augmentation in conjunction with sinus membrane elevation: an experimental study

Background: There have been reports of successful bone formation with sinus floor elevation induced by simply elevating the maxillary sinus membrane and filling the sinus cavity with a blood clot. Purpose: We investigated the feasibility of maxillary sinus floor augmentation using the patient's own venous blood in conjunction with a sinus membrane elevation procedure. Materials and methods: An implant that protruded 8 mm into the maxillary sinus after sinus membrane elevation was placed in the maxillary sinus of six adult female mongrel dogs. The resulting space between the membrane and the sinus floor was filled with autologous venous blood retrieved from each dog. The implants were left in place for 6 months. Results: During the experimental period, the created space collapsed and the sinus membrane fell down onto the implant. A small amount of new bone formation occurred in the space created by the collapsed membrane. The average height of newly formed bone around the implants in the sinus was 2.7±0.7 mm on the buccal side and 0.6±0.3 mm on the palatal side. Conclusion: The results of this pilot study indicate that blood clots do not have sufficient integrity to enable the sinus membrane to remain in an elevated position for therapeutically effective periods of time. Accordingly, it is recommended that this method be used only when a small aount of new bone formation is necessary around implants in the maxillary sinus cavity. To cite this article:
Kim H‐R, Choi B‐H, Xuan F, Jeong S‐M. The use of autologous venous blood for maxillary sinus floor augmentation in conjunction with sinus membrane elevation: an experimental study.
Clin. Oral Impl. Res. 21 , 2010; 346–349.
doi: 10.1111/j.1600‐0501.2009.01855.x     

Effect of platform switching on peri-implant bone levels: a randomized clinical trial

Objective: The concept of platform switching has been introduced to implant dentistry based on observations of reduced peri‐implant bone loss. However, randomized clinical trials are still lacking. This study aimed to test the hypothesis that platform switching has a positive impact on crestal bone‐level changes. Material and methods: Two implants with diameters of 4 mm were inserted epicrestally into one side of the posterior mandibles of 25 subjects. After 3 months of submerged healing, the reentry surgery was performed. On the randomly placed test implant, an abutment 3.3 mm in diameter was mounted, resulting in a horizontal circular step of 0.35 mm (platform switching). The control implant was straight, with an abutment 4 mm in diameter. Single‐tooth crowns were cemented provisionally. All patients were monitored at short intervals over the course of 1 year. Standardized radiographs and microbiological samples from the implants' inner spaces were obtained at baseline (implant surgery), and after 3, 4, and 12 months. Results: After 1 year, the mean radiographic vertical bone loss at the test implants was 0.53±0.35 mm and at the control implants, it was 0.58±0.55 mm. The mean intraindividual difference was 0.05±0.56 mm, which is significantly <0.35 mm (P=0.0093, post hoc power 79.9%). The crestal bone‐level changes depended on time (P<0.001), but not on platform switching (P=0.4). The implants' internal spaces were contaminated by bacteria, with no significant differences in the total counts between the test and the control at any time point (P=0.98). Conclusions: The present randomized clinical trial could not confirm the hypothesis of a reduced peri‐implant bone loss at implants restored according to the concept of platform switching. To cite this article:
Enkling N, Jöhren P, Klimberg V, Bayer S, Mericske‐Stern R, Jepsen S. Effect of platform switching on peri‐implant bone levels: a randomized clinical trial.
Clin. Oral Impl. Res. 22 , 2011; 1185–1192.
doi: 10.1111/j.1600‐0501.2010.02090.x     

Early and immediate loading of titanium implants with fluoride-modified surfaces: results of 5-year prospective study

Objective: Multiple experimental and animal studies have shown that topographic, mechanical and chemical properties of implant surfaces lead to in vivo responses such as increased bone formation, increased bone anchorage and reduced healing time. A fluoride modification of the titanium implant surface also seems to positively influence bone anchorage as compared with unmodified titanium implants. Using implant survival and marginal bone loss as primary outcome parameters, the purpose of the present prospective study was to investigate whether a fluoride modification of the titanium implant surface has positive clinical effects. Materials and methods: The 17 patients included in this study received 49 Astra Tech OsseoSpeed^? implants for various indications in the maxilla and mandible. Implants were either loaded immediately or after a mean healing period of 9.56 weeks. Fifteen patients were followed up clinically including radiographic examination for 5 years. Forty‐two implants were assessed for implant survival, marginal bone loss, surgical and/or prosthetic complications, presence or absence of plaque, signs of inflammation and size of the papilla. Results: Of the original 17 patients, 15 patients were available for the full 60‐month follow‐up. One early implant failure occurred, leading to an implant survival rate of 97%. Radiographic analyses demonstrated stable bone conditions with a mean marginal bone loss of 0.1 mm (SD 0.4 mm, min ?0.7 mm, max 1.7 mm) after 5 years of function. Immediately loaded implants did not show a different mean marginal bone loss as compared with implants that were not loaded immediately. Repeated soft‐tissue examinations revealed healthy conditions in terms of 6.1% plaque and 4.2% of the implants with signs of inflammation at the 5‐year control. Discussion: Implants used in this study had high survival and success rates after 5 years. Marginal bone was well maintained, irrespective of the loading regime. To cite this article:
Mertens C, Steveling HG. Early and immediate loading of titanium implants with fluoride‐modified surfaces: results of 5‐year prospective study.
Clin. Oral Impl. Res. xx , 2011; 000–000.     

Effects of a calcium phosphate coating on the osseointegration of endosseous implants in a rabbit model

Objectives: The aim of the present study was to evaluate a Ca–P coated implant surface in a rabbit model. The Ca–P surface (test) was compared to the titanium porous oxide surface (control) in terms of bone‐to‐implant contact (BIC) and removal torque value. Materials and methods: Two hundred and sixteen dental implants were inserted in the tibia and in the femur of 36 rabbits. One hundred and eight were represented by Ca–P oxidized surface implant and other 108 were titanium porous oxide surface modified implants. Each rabbit received six implants. Animals were sacrificed after 2, 4 and 9 weeks of healing. Each group included 12 rabbits. The femoral implant and the proximal implant of the tibia of each animal were subjected to the histologic analysis and the distal implants of the tibia underwent removal torque test (RTQ). Results: Histological analysis in terms of BIC and RTQ did not revealed any significant difference between the Ca–P oxidized surface and the oxidized surface at 2 and 4 weeks. At 9 weeks, the oxidized surface demonstrated better results in terms of RTQ in the tibia. Conclusion: In conclusion, findings from the present study suggested that the Ca–P coating had no beneficial effect in improving bonding strength at the bone–implant interface either at 2, 4 and 9 weeks. To cite this article:
Fontana F, Rocchietta I, Addis A, Schupbach P, Zanotti G, Simion M. Effects of a calcium phosphate coating on the osseointegration of endosseous implants in a rabbit model
Clin. Oral Impl. Res. 22 , 2011; 760–766
doi: 10.1111/j.1600‐0501.2010.02056.x     

Influence of surface roughness and shape on microdamage of the osseous surface adjacent to titanium dental implants

Objectives: To assess the relationship between smooth and roughened implant surfaces of straight and narrow configurations with respect to microdamage of the bone surface during placement of dental implants Materials and methods: Straight and tapered, rough and smooth surface Nobel Biocare implants were placed into sheep mandibles. Microdamage within the bone adjacent to the implant surface was quantitated using a semi‐automated digitized histomorphometric method. Results: Independent of implant type, microdamage, microcracks, cross‐hatch damage and diffuse damage were significantly higher close to the implants compared with far from the implants. Microcracks and cross‐hatch damage were higher for the rough cylindrical implants than all the other implant types. Conclusions: Insertion of a rough cylindrical implant type results in an increased fraction of microdamaged bone matrix in comparison to rough tapered, smooth cylindrical and smooth tapered implants. To cite this article:
Bartold PM, Kuliwaba JS, Lee V, Shah S, Marino V, Fazzalari NL. Influence of surface roughness and shape on microdamage of the osseous surface adjacent to titanium dental implants.
Clin. Oral Impl. Res. 22 , 2011; 613–618
doi: 10.1111/j.1600‐0501.2010.02024.x     

A prospective,controlled clinical trial evaluating the clinical and radiological outcome after 3 years of immediately placed implants in sockets exhibiting periapical pathology

Objectives: The aim of the present study was to compare the clinical and radiological outcome of immediately placed implants in sockets with or without periapical pathology 3 years after implant placement. Materials and methods: Twenty‐nine patients with immediate implant placement were clinically and radiologically followed 3 years after implant placement (test group: 16 patients without periapical pathology, control group: 13 patients with periapical pathologies). Clinical (full‐mouth bleeding score, full‐mouth plaque score, clinical attachment level measurements and width of keratinized mucosa buccaly of the implant) and radiological parameters (vertical distance from the implant shoulder to the first bone‐to‐implant contact [IS‐BIC]) were assessed. Both 95% confidence intervals, as well as results of statistical tests (one‐sample, two‐sample and paired t‐test) were provided. Results: The implant survival rate was 100% for all 29 implants after 3 years. The clinical and radiological parameters showed no statistically significant difference between the test and the control group at 3 years (two‐sample t‐test). The IS‐BIC was between 1.54 ± 0.88 mm (mesial, test) and 1.69 ± 0.92 mm (distal, test). Between the 1‐ and 3‐year visit the IS‐BIC increased in both groups significantly on one side of the implant: 0.30 ± 0.37 mm (mesial, test) and 0.33 ± 0.43 mm (distal, control) (one‐sample t‐test). None of the 13 examined radiographs of implants immediately placed in sockets with periapical pathologies revealed retrograde peri‐implantitis after 3 years. Conclusion: It is concluded within the limitations of this study, that after careful debridement of the extraction socket, immediate placement of implants into sites with periapical pathologies can be a successful treatment modality for at least 3 years with no disadvantages in clinical and radiological parameters to immediately placed implants into healthy sockets. To cite this article:
Truninger TC, Philipp AOH, Siegenthaler DW, Roos M, Hämmerle CHF, Jung RE. A prospective, controlled clinical trial evaluating the clinical and radiological outcome after 3 years of immediately placed implants in sockets exhibiting periapical pathology.

Clin. Oral Impl. Res. 22 , 2011; 20–27.
doi: 10.1111/j.1600‐0501.2010.01973.x     

Osseointegration of one‐piece zirconia implants compared with a titanium implant of identical design: a histomorphometric study in the dog

Objective: The aim of this study was to evaluate osseointegration of one‐piece zirconia vs. titanium implants depending on their insertion depth by histomorphometry. Material and methods: Four one‐piece implants of identical geometry were inserted on each side of six mongrel dogs: (1) an uncoated zirconia implant, (2) a zirconia implant coated with a calcium‐liberating titanium oxide coating, (3) a titanium implant and (4) an experimental implant made of a synthetic material (polyetheretherketone). In a split‐mouth manner they were inserted in submerged and non‐submerged gingival healing modes. After 4 months, dissected blocks were stained with toluidine blue in order to histologically assess the bone‐to‐implant contact (BIC) rates and the bone levels (BL) of the implants. Results: All 48 implants were osseointegrated clinically and histologically. Histomorphometrically, BL in the crestal implant part did not differ significantly with regard to material type or healing modality. The submerged coated zirconia implants tended to offer the most stable crestal BL. The histometric results reflected the different healing modes by establishing different BL. The median BIC of the apical implant part of the zirconia and titanium group amounted to 59.2% for uncoated zirconia, 58.3% for coated zirconia, 26.8% for the synthetic material and 41.2% for titanium implants. Conclusions: Within the limits of this animal study, it is concluded that zirconia implants are capable of establishing close BIC rates similar to what is known from the osseointegration behaviour of titanium implants with the same surface modification and roughness. To cite this article:
Koch FP, Weng D, Krämer S, Biesterfeld S, Jahn‐Eimermacher A, Wagner W. Osseointegration of one‐piece zirconia implants compared with a titanium implant of identical design: a histomorphometric study in the dog.
Clin. Oral Impl. Res. 21 , 2010; 350–356.
doi: 10.1111/j.1600‐0501.2009.01832.x     

Dental implant treatment for two adjacent missing teeth in the maxillary aesthetic zone: a comparative pilot study and test of principle

Aim: The aim of this prospective comparative pilot study was to evaluate hard and soft peri‐implant tissues in patients with a missing adjacent central and lateral upper incisor treated with either one implant and an implant crown with a cantilever or two implants with solitary implant crowns up to 1 year after functional loading. Material and methods: In the “Implant–cantilever group”, five patients were treated with one dental implant in the region of the central incisor (NobelReplace Groovy Regular Platform). In the “Implant–implant group”, five patients were treated with two adjacent dental implants: at the position of the central incisor (NobelReplace Groovy Regular Platform) and at the position of the lateral incisor (NobelReplace Groovy Narrow Platform). Implant survival, pocket probing depth, papilla index, marginal bone level and patient satisfaction were assessed during a 1‐year follow‐up period. Results: No implants were lost during the 1‐year follow‐up. Mean pocket probing values of the implants were comparable between the two groups. Papilla index scores in both groups were relatively low, pointing towards a compromised papilla. Marginal bone loss was minimal and comparable between the groups. Patient satisfaction was very high in both groups. Conclusion: In this 1‐year prospective comparative study, no large differences in hard‐ and soft‐tissue levels could be shown between patients with a missing central and lateral upper incisor treated with either one implant and an implant crown with a cantilever or two implants with solitary implant crowns. To cite this article:
Tymstra N, Raghoebar GM, Vissink A, Meijer HJA. Dental implant treatment for two adjacent missing teeth in the maxillary aesthetic zone: a comparative pilot study and test of principle.
Clin. Oral Impl. Res. 22 , 2011; 207–213.
doi: 10.1111/j.1600‐0501.2010.02017.x