Accuracy of cone beam computed tomography in assessing peri-implant bone defect regeneration: a histologically controlled study in dogs

Objective: To assess the accuracy of cone‐beam computed tomography (CBCT) in terms of buccal bone‐wall configuration and peri‐implant bone defect regeneration after guided bone regeneration (GBR). Material and methods: Titanium implants were inserted into standardized box‐shaped defects in the mandible of 12 foxhounds. Defects of one side were augmented following the principle of GBR, while the other side was left untreated. Radiological evaluation was performed using CBCT and compared with histomorphometrical measurements of the respective site serving as a validation method. Results: Non‐augmented control sites providing a horizontal bone width (BW) of<0.5 mm revealed a significantly lower accuracy between the radiological and the histological evaluation of the buccal defect depth (1.93 ± 1.59 mm) compared with the group providing a BW of >0.5 mm (0.7 ± 0.7 mm) (P<0.05, Mann–Whitney U‐test). In GBR‐treated defects, the subgroup <0.5 mm (1.49 ± 1.29 mm) revealed a significantly higher difference between CBCT and histology compared with >0.5 mm (0.82 ± 1.07) (P>0.05, Mann–Whitney U‐test). However, a radiological discrimination between original bone, integrated and non‐integrated bone substitute material was not reliable. Additionally, it was found that a minimum buccal BW of 0.5 mm was necessary for the detection of bone in radiology. Conclusion: The evaluation of peri‐implant bone defect regeneration by means of CBCT is not accurate for sites providing a BW of <0.5 mm. Moreover, a safe assessment of the success of the GBR technique is not possible after the application of a radiopaque bone substitute material. To cite this article:
Fienitz T, Schwarz F, Ritter L, Dreiseidler T, Becker J, Rothamel D. Accuracy of cone beam computed tomography in assessing peri‐implant bone defect regeneration: a histologically controlled study in dogs.
Clin. Oral Impl. Res. 23 , 2012; 882–887.
doi: 10.1111/j.1600‐0501.2011.02232.x     

Influence of bony defects on implant stability

Introduction: The purpose of this study was to analyze the evolution of implant mechanical stability in different types/sizes of bony defects using both Periotest and Osstell devices as “objective tools.” Materials and methods: Thirty‐two implants were randomly allocated to one of the four types of bone defects: marginal bone loss, peri‐apical bone defect, constant width dehiscence and constant length dehiscences. Periotest/Osstell measurements were completed before and during staged bone removal (to enlarge defect size). Results: Significant differences (P<0.05) with initial values were found after a 2 mm marginal bone removal (Osstell/Periotest); for a peri‐apical bone lesion, after removal of 5 mm (Osstell) or 8 mm (Periotest); for a 6‐mm‐long dehiscence, after removal up to 180° of the implant perimeter (Osstell/Periotest); for a 3‐mm‐wide dehiscence, after removal of 10 mm (Osstell) or 6 mm (Periotest). Conclusion: Periotest and Osstell are in general not very sensitive in the identification of peri‐implant bone destruction, except for marginal bone loss. To cite this article:
Merheb J, Coucke W, Jacobs R, Naert I, Quirynen M. Influence of bony defects on implant stability.
Clin. Oral Impl. Res. 21 , 2010; 919–923.
doi: 10.1111/j.1600‐0501.2010.01932.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     

Bone regeneration after topical BMP-2-gene delivery in circumferential peri-implant bone defects

Objectives: The aims of this study were to evaluate the rate of bone formation and osseointegration after topical gene delivery with a liposomal vector system carrying bone morphogenetic protein (BMP)‐2 cDNA in combination with a collagen carrier and autologous bone as a carrier in freshly created peri‐implant bone defects. Materials and methods: Eight domestic pigs received nine calvariae defects each (10 × 7 mm). A dental implant was inserted into the centre of each defect. In the test groups, the remaining space was filled with the liposomal vector/BMP‐2 complex combined with a collagen carrier (n=18) or an autologous bone graft (n=18). Control groups were collagen only (n=18) and autologous bone graft only (n=18). Results: There was a significant difference in mineralisation rate in the BMP‐2/bone graft (29.9%± 4.8 and 68.3%± 7.2) and bone graft only (22.6%± 2.6 and 49.4%± 13.9) groups after 7 and 28 days. Mineralisation values were also significantly higher in the BMP‐2/collagen group (21.2%± 16.2 and 53.1%± 12.5) compared with the collagen‐only group (8.2%± 7 and 41%± 8.1) in two different regions after 28 days. Also the bone‐to‐implant contact was significantly increased in the BMP‐2/bone graft group after 28 days and in the BMP‐2/collagen group after 7 and 28 days compared with their control groups. Conclusions: The results of this study show a significantly positive effect of liposomal vector/BMP‐2 on bone regeneration and osseointegration in bony circumferential peri‐implant defects.     

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     

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

Objectives: The aim of the present study was to evaluate the dimensional changes of peri‐implant tissues obtained by implant placement, bone and soft tissue augmentation, prosthetic reconstruction and 1 year of function using a new, non‐invasive method for volumetric measurements. Materials and Methods: In 16 patients, the missing central or lateral maxillary incisor was reconstructed with an implant‐supported single crown. Impressions were taken before (t1), after implant placement with guided bone regeneration using DBBM and a PTFE membrane (t2), after soft tissue augmentation (t3), immediately after crown placement (t4) and 1 year later (t5). The cast models were optically scanned and digitally superimposed allowing qualitative and quantitative analysis of alterations of the labial peri‐implant tissue contour. In addition, the crown length and papilla height were measured at crown placement (t4) and after 1 year (t5). Results: Fifteen patients were available for recall after 1 year. During therapy, a mean gain in distance in the labial direction of 1.27±0.67 mm was observed after the surgical procedures. One year after crown insertion, a mean loss of 0.04±0.31 mm in the labial direction was recorded. During the same period, the crown length increased by a mean of 0.22±0.57 mm and the papilla height by 0.07±0.61 mm. The degree and pattern of tissue change following crown insertion were highly variable between individuals, irrespective of the amount and quality of previously augmented tissues. Conclusions: The clinical procedures were effective in augmenting peri‐implant tissue volume that remained stable to a high degree within 1 year after crown insertion. Large inter‐individual variations regarding the tissue alterations were observed. To cite this article:
Schneider D, Grunder U, Ender A, Hämmerle CHF, Jung RE. Volume gain and stability of peri‐implant tissue following bone and soft tissue augmentation: 1‐year results from a prospective cohort study
Clin. Oral Impl. Res. 22 , 2011; 28–37.
doi: 10.1111/j.1600‐0501.2010.01987.x     

Radiological and clinical follow-up of machined- and anodized-surface implants after mean functional loading for 33 months

Abstract: The purpose of this retrospective study was to compare peri‐implant bone loss and mucosal conditions around machined‐surface (MS) and anodized‐surface (AS) interforaminal implants in the mandible at least 30 months after placement. Fifty patients, each treated with four interforaminal screw‐type implants consecutively, were included. Thirty‐one patients (62%) with a total number of 124 implants (64 MS and 60 AS implants, both Brånemark type MKIII) were available for follow‐up. Rotational panoramic radiographs were used for evaluating marginal bone loss. Clinically, marginal plaque index (mPI), bleeding on probing (BOP) and pocket probing depth (PPD) were evaluated. AS implants showed significantly less marginal bone loss than MS implants (−1.17±0.13 vs. −1.42±0.13 mm; P=0.03). Marginal bone loss around distal implants was less pronounced at AS implants (−1.05±0.14 mm) when compared with MS implants (−1.46±0.14 mm; P=0.05). Within the smoking group, there was less peri‐implant bone loss around AS implants than around MS implants (−1.08±0.27 vs. −1.83±0.2; P=0.04). No differences between MS and AS implants were found with respect to mPI (57% vs. 67%), BOP (21% vs. 17%) and mean PPD (2.59±0.29 vs. 2.56±0.28 mm). Overall, both types of implants, in combination with bar‐supported overdentures, can produce excellent long‐term results in the interforaminal edentulous mandible with less peri‐implant bone loss around rough implant surfaces, which had beneficial effects at distal implants and in smokers.     

Radiographic alveolar bone changes following ridge preservation with two different biomaterials

Objectives: The aim of this randomized controlled trial was to evaluate radiographical bone changes following alveolar ridge preservation with a synthetic bone substitute or a bovine xenograft. Methods: Alveolar ridge preservation was performed in 27 patients randomized in two groups. In the test group (n=14), the extraction socket was treated with Straumann bone ceramic^® (SBC) and a collagen barrier membrane (Bio‐Gide^®), whereas in the control group (n=13) with deproteinized bovine bone mineral and the same barrier. Standardized periapical X‐rays were taken at 4 time points, BL: after tooth extraction, GR: immediately after socket grafting, 4M: 16 weeks, 8M: 32 weeks post‐operatively. The levels of the alveolar bone crest at the mesial (Mh), and distal (Dh) and central aspects of the socket were measured at all time points. All the radiographs obtained were subtracted from the follow‐up images. The gain, loss and unchanged areas in terms of grey values were tested for significant difference between the two groups. Results: In the test group, the Mh and Dh showed a mean difference (± standard deviation) of 0.9 ± 1.2 and 0.7 ± 1.8 mm, respectively, among BL‐8M. In the control group, the Mh and Dh showed a mean difference of 0.4 ± 1.3 and 0.7 ± 1.3 mm, respectively (P>0.05). Both treatments presented similar gain in grey values between BL‐GR, BL‐4M and BL‐8M. The SBC presented less loss in grey values between BL‐4M and BL‐8M (P<0.05). Radiographic assessment underestimated the intrasurgical measurements (mesial and distal) of an average 0.3 mm (95% CI, 0.02–0.6). Conclusion: Both types of bone grafts presented similar radiographic alveolar bone changes when used for alveolar ridge preservation. To cite this article:
Mardas N, D'Aiuto F, Mezzomo L, Arzoumanidi M, Donos N. Radiographic alveolar bone changes following ridge preservation with two different biomaterials.
Clin. Oral Impl. Res. 22 , 2011; 416–423.     

Stability, marginal bone loss and survival of standard and modified sand-blasted, acid-etched implants in bilateral edentulous spaces: a prospective 15-month evaluation

Objectives: Chemical modification of the already proven sand‐blasted and acid‐etched (SLA) implant had increased its surface wettability and consequent early‐term osseointegration characteristics. The aim of this clinical trial was to compare the stability changes, success, survival, peri‐implant parameters and marginal bone loss (MBL) of the early‐loaded standard (SLA) and modified sand‐blasted, acid‐etched (modSLA) implants. Material and methods: A total of 96 SLA and modSLA implants were placed in a bi‐lateral, cross‐arch position to the jaws of 22 patients. Resonance frequency analysis (RFA) was used to measure the implant stability in the surgery and following healing after 1, 3 and 6 weeks. At the stage of loading, a panoramic X‐ray was obtained and RFA measurement was repeated for all implants. Implants were restored by metal–ceramic crowns and followed for 1 year to determine the success, survival rate, peri‐implant parameters and MBL. Results were compared by one‐ and two‐way ANOVA, log‐rank test and generalized linear mixed models (P<0.05). Results: One modSLA implant was lost after 3 weeks following the surgery yielding to a 100 and 97.91% success rate for SLA and modSLA implants, respectively (P=0.323). At the loading stage, modSLA implants showed significantly lower MBL (0.18 ± 0.05 mm) than SLA implants (0.22 ± 0.06 mm; P=0.002). In the loading stage, RFA value of the modSLA implants (60.42 ± 6.82) was significantly higher than the both implant types in the surgical stage (55.46 ± 8.29 and 56.68 ± 8.19), and following 1 (56.08 ± 7.01 and 55.60 ± 9.07) and 3 weeks of healing (55.94 ± 5.95 and 55.40 ± 6.50 for SLA and modSLA implants, respectively). Conclusions: modSLA implants demonstrated a better stability and a reduced MBL at the loading stage. Both SLA and modSLA implants demonstrated a favorable success and survival at the end of 15‐month follow‐up. To cite this article :
Karabuda ZC, Abdel‐Haq J. Arιsan V. Stability, marginal bone loss and survival of standard and modified sand‐blasted, acid‐etched implants in bilateral edentulous spaces: a prospective 15‐month evaluation.
Clin. Oral Impl. Res. 22 , 2011; 840–849
doi: 10.1111/j.1600‐0501.2010.02065.x     

Immediately restored one-piece single-tooth implants with reduced diameter: one-year results of a multi-center study

Objectives: The aim of the present multi‐center study was to evaluate the treatment outcome of immediately restored one‐piece single‐tooth implants with a diameter of 3 mm after 1 year. Material and methods: A total of 57 one‐piece implants (NobelDirect^® 3.0) were inserted in 47 patients (26 females, 21 males) with a mean age of 31 years (range: 17–76 years) at five different centers. The implants replaced maxillary lateral incisors and mandibular incisors. The implants were placed either in conjunction with tooth extraction or in healed sites, and all implants were immediately restored with a provisional resin crown. If needed, the abutment part of the implant was prepared before crown cementation. The permanent crown was placed after 1.9–14.5 months. Radiographs were taken at implant insertion as well as after 6 and 12 months to evaluate the peri‐implant marginal bone level and bone loss. Moreover, plaque, bleeding on probing and complications were assessed. Results: A total of 44 patients (23 females, 21 males) with 54 implants were available for the 1‐year follow‐up. One implant was lost, thus the 1‐year implant survival was 98%. A statistically significant mean marginal bone loss was observed between baseline and 6 months (1.1 mm, range: ?0.7 to 4.4 mm; n=49) and between baseline and 12 months (1.6 mm, range: ?0.8 to 4.6 mm; n=50). A total of 18% of the implants were characterized by a bone loss of more than 3 mm. No bleeding on probing was observed around 83% of the implants. Plaque was registered at 15% of the implants. The most common complications were related to the provisional crown, i.e. fracture (n=3) and loss of retention (n=3). Conclusions: A high 1‐year implant survival was observed in the present study. However, the excessive peri‐implant marginal bone loss around several implants indicates that this implant should be used with caution until further studies have been conducted. To cite this article:
Zembi? A, Johannesen LH, Schou S, Malo P, Reichert T, Farella M, Hämmerle CHF. Immediately restored one‐piece single‐tooth implants with reduced diameter: one‐year results of a multi‐center study.
Clin. Oral Impl. Res. 23 , 2012; 49–54.
doi: 10.1111/j.1600‐0501.2011.02174.x     

Comparison of peri‐implant clinical and radiographic status around short (6 mm in length) dental implants placed in cigarette‐smokers and never‐smokers: Six‐year follow‐up results

Background

It is hypothesized that peri‐implant clinical and radiographic inflammatory parameters (probing depth [PD], bleeding on probing [BOP] and plaque index [PI]; and radiographic (crestal bone loss [CBL]) are worse among cigarette‐smokers (CS) compared with never‐smokers (NS) with short implants.

Purpose

The present 6‐year follow‐up retrospective study compared the peri‐implant clinical and radiographic parameters in CS and NS with short dental implants (6 mm in length).

Materials and methods

Fifty‐six male individuals were included. These individuals divided into 2 groups as follows: (a) Group‐1: 29 self‐reported systemically healthy CS with 48 short‐implants; and (b) Group‐2: 27 self‐reported systemically healthy NS with 43 short implants. Peri‐implant PD, PI, BOP, and CBL were measured. Group comparisons were done using the Kruskal‐Wallis test and sample size was estimated. Level of significance was set at P values < .05.

Results

In groups 1 and 2, the follow‐up durations were 6.2 ± 0.1 years and 6.1 ± 0.3 years, respectively. A cigarette smoking history of 8.9 ± 3.6 pack years was reported by individuals in Group‐1. At follow‐up, scores of peri‐implant PD, BOP, PI, and mesial and distal CBL were comparable around short implants in both groups.

Conclusion

Under strict oral hygiene maintenance protocols, short dental implants can remain functionally stable in CS in a manner similar to NS.     

Biofunctionalization of titanium implants with a biomimetic active peptide (P‐15) promotes early osseointegration

Objectives: The early stages of peri‐implant bone formation play an essential role in the osseointegration and long‐term success of dental implants. By incorporating bioactive coatings, this biofunctionalization of implant surfaces may enhance the attachment of the implant to the surrounding bone and stimulate bone regeneration. Material and methods: To demonstrate faster osseointegration, the surfaces of dental implants were grit‐blasted and acid‐etched. They were then coated with hydroxyapatite (HA) and experimental implants were further coated with a biomimetic active peptide (P‐15) in one of two concentrations. These biofunctionalized samples and controls with no peptide were placed in the forehead region of 12 adult pigs. Six animals were evaluated for a period of 14 or 30 days. Results: Histomorphometric analysis demonstrated that the implants with the high concentration of P‐15 had significantly higher percentage of bone‐to‐implant contact (BIC) at 14 (P=0.018) and 30 (P=0.015) days compared with the other groups. Both concentrations of P‐15 showed increased peri‐implant bone density compared to the control group at 30 days. Conclusion: Biofunctionalization of the implant surface with a biomimetic active peptide leads to significantly increased BIC rates at 14 and 30 days and higher peri‐implant bone density at 30 days. To cite this article:
Lutz R, Srour S, Nonhoff J, Weisel T, Damien CJ, Schlegel KA. Biofunctionalization of titanium implants with a biomimetic active peptide (P‐15) promotes early osseointegration.
Clin. Oral Impl. Res. 21 , 2010; 726–734.
doi: 10.1111/j.1600‐0501.2009.01904.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     

Peri‐implant parameters in head and neck reconstruction: influence of extraoral skin or intraoral mucosa

Objective: This study is designed to assess dental implants supporting overdentures in edentulous patients with operated head and neck malignancies using parameters to detect peri‐implant disease. Material and methods: Thirty‐four implants supporting overdentures in 34 oral cancer patients were examined. Clinical parameters [plaque index, probing depth, bleeding on probing (BOP), origin of peri‐implant soft tissue, and amount of irradiation] were recorded, and microbiological identification of periodontal pathogens was carried out by DNA–DNA hybridization. To identify yeast species, the samples were cultivated on Sabouraud agar plates and subsequently identified by API 20C AUX plates. An implant site showing BOP, probing pocket depth (PPD)≥5 mm and radiographic vertical bone loss was considered to have peri‐implant disease. Results: Colonization by periodontal pathogens was found on 15 implants, while yeast species were found in 14 cases. Using a univariate analysis, none of the investigated parameters (microbiologic sign, detection of yeast, origin of peri‐implant soft tissue and irradiation) were significantly correlated to signs of peri‐implant disease. In the multivariate analysis, yeast [odds ratio (OR) 12.32, P=0.033] and periodontal pathogen (OR 9.88, P=0.046) were significant predictor variables for peri‐implant disease. Yeasts were less frequently detected around implants placed in re‐vascularized skin flaps if irradiation was set as a confounder (P=0.019). Conclusions: With respect to the pilot study nature of the study peri‐implant soft tissue origin and irradiation had little influence on the development of peri‐implant disease. Yeast and periodontal pathogen were explanatory variables for the development of peri‐implant disease. Considering the effect of irradiation on the prevalence of yeast, yeast was less frequently observed in peri‐implant soft tissue of the skin. Based on these data, future studies on the role of yeast and soft tissue in peri‐implant disease should be encouraged. To cite this article:
Kwon Y‐D, Karbach J, Wagner W, Al‐Nawas B. Peri‐implant parameters in head and neck reconstruction: influence of extraoral skin or intraoral mucosa.
Clin. Oral Impl. Res. 21 , 2010; 316–320.
doi: 10.1111/j.1600‐0501.2009.01763.x     

The effect of maximum bite force on marginal bone loss of mini‐implants supporting a mandibular overdenture: a randomized controlled trial

Objectives: To evaluate the effect of maximum bite force (mBF) on marginal bone loss (MBL) around mini‐implants in edentulous patients wearing mandibular overdentures with two retention systems: ball and bar. Material and methods: Forty‐five totally edentulous patients were selected from a public health center. All of them received two mini‐implants (1.8 × 15 mm; Sendax^®) in the anterior mandible using a minimally invasive technique. A single randomization was performed to allocate the patients in two groups. Group I (n=22) received two single ball‐type mini‐implants and Group II (n=23) received two mini‐implants splinted with a prefabricated bar. The mBF was recorded using a press‐sensitive sheet Dental Prescale^® (Fuji) and MBL using standardized radiographs of each mini‐implant at the baseline and 5, 7, 10, and 15 months after surgery; the values were compared between groups. Results: Two members of Group I failed to complete the study, decreasing the number of participants to 20. There was no relationship between the mBF and the MBL of the mini‐implants (Spearman's ρr_s=0.147; P=0.378). At the 15‐month follow‐up, the average mBF for Group I (ball) was 247.53 ± 132.91 N and that of Group II (bar) only 203.23 ± 76.85 N (Mann–Whitney test; P=0.586). The MBL values were also higher for Group I (1.40 ± 1.02 mm) than Group II (0.84 ± 0.66 mm) during the entire 15‐month follow‐up period (Mann–Whitney test; P=0.077). Conclusions: No relationship was found between mBF and MBL for patients wearing overdentures retained on mini‐implants using bar or ball attachment systems. To cite this article:
Jofré J, Hamada T, Nishimura M, Klattenhoff C. The effect of maximum bite force on marginal bone loss of mini‐implants supporting a mandibular overdenture: a randomized controlled trial.
Clin. Oral Impl. Res. 21 , 2010; 243–249.
doi: 10.1111/j.1600‐0501.2009.01834.x     

Graft‐Free Maxillary Sinus Floor Elevation: A Systematic Review and Meta‐Analysis

Background: This systematic review and meta‐analysis aims to investigate survival rates of dental implants placed simultaneously with graft‐free maxillary sinus floor elevation (GFSFE). Factors influencing amount of vertical bone gain (VBG), protruded implant length (PIL) in sinus at follow‐up (PILf), and peri‐implant marginal bone loss (MBL) are also evaluated. Methods: Electronic and manual searches for human clinical studies on simultaneous implant placement and GFSFE using the lateral window or transcrestal approach, published in the English language from January 1976 to March 2016, were conducted. The random‐effects model and mixed‐effect meta‐regression were used to analyze weighted mean values of clinical parameters and evaluate factors that influenced amount of VBG. Results: Of 740 studies, 22 clinical studies were included in this systematic review. A total of 864 implants were placed simultaneously with GFSFE at edentulous sites having mean residual bone height of 5.7 ± 1.7 mm. Mean implant survival rate (ISR) was 97.9% ± 0.02% (range: 93.5% to 100%). Weighted mean MBL was 0.91 ± 0.11 mm, and it was significantly associated with the postoperative follow‐up period (r = 0.02; R² = 43.75%). Weighted mean VBG was 3.8 ± 0.34 mm, and this parameter was affected significantly by surgical approach, implant length, and PIL immediately after surgery (PILi) (r = 2.82, 0.57, 0.80; R² = 19.10%, 39.27%, 83.92%, respectively). Weighted mean PILf was 1.26 ± 0.33 mm (range: 0.3 to 2.1 mm). Conclusion: Within limitations of the present systematic review, GFSFE with simultaneous implant placement can achieve satisfactory mean ISR of 97.9% ± 0.02%.     

Intermittent parathyroid hormone fails to stimulate osseointegration in diabetic rats

Objectives: Diabetes is considered a risk factor in the osseointegration of dental implants, which suggests that these patients might benefit from anabolic therapies. Preclinical studies, including investigations by this research group, revealed that intermittent administration of parathyroid hormone (PTH) stimulates bone formation on the surface of titanium implants under physiological conditions. However, the anabolic effect of PTH on osseointegration under the hyperglycemic condition of diabetes is unknown. Methods: The ability of PTH to stimulate osseointegration was investigated in 40 female Wistar rats that were randomly divided into the following treatment groups: diabetes, diabetes plus PTH, control, and control plus PTH. Diabetes was induced by intraperitoneal injection of streptozotocin (45 mg/kg) at 1 week before implantation. Rats received PTH at a dose of 60 μg/kg or a vehicle by subcutaneous injection starting at the day of implant insertion into the tibia. Histomorphometric analysis was performed after 4 weeks. Results: The medullary peri‐implant bone area significantly increased in rats receiving PTH in comparison with the control group (41±12% to 20±12%; P<0.01). Moreover, there was an increased bone‐to‐implant contact (BIC) area in animals treated with PTH (47±18% to 27±16%; P<0.05). In contrast, diabetic rats failed to benefit from the anabolic treatment. A similar peri‐implant bone area occurred in the diabetes group, independent of treatment with PTH (13±9% to 15±6%; P>0.05). Moreover, PTH did not affect the BIC area under hyperglycemic conditions (16±12% to 16±8%; P>0.05). No significant changes were observed in the cortical compartment of all groups. Conclusion: These results demonstrate that the metabolic characteristics of the diabetic rats produced a condition that was unable to respond to PTH treatment. These findings led us to hypothesize that metabolic control of diabetes might be a critical determinant when diabetic patients are undergoing anabolic therapy to enhance osseointegration. To cite this article:
Kuchler U, Spilka T, Baron K, Tangl S, Watzek G, Gruber R.
Intermittent parathyroid hormone fails to stimulate osseointegration in diabetic rats.
Clin. Oral Impl. Res. 22 , 2011; 518–523
doi: 10.1111/j.1600‐0501.2010.02047.x     

Evaluation of implant osseointegration with different regeneration techniques in the treatment of bone defects around implants: an experimental study in a rabbit model

Aim: The aim of this study was to evaluate the osseointegration of implants placed in areas with artificially created bone defects, using three bone regeneration techniques. Material and methods: The experimental model was the rabbit femur (16), where bone defects were created and implants were placed. The peri‐implant bone defects were filled with a deproteinized bovine bone mineral, NuOss^? (N), NuOss^? combined with plasma rich in growth factors (PRGF) (N+PRGF), NuOss^? covered by an RCM⁶ membrane (N+M), or remained unfilled (control group [C]). After 4 and 8 weeks, the animals were euthanized and bone tissue blocks with the implants and the surrounding bone tissue were removed and processed according to a histological protocol for hard tissues on non‐decalcified ground sections. The samples were studied by light and electron scanning microscopy, histometric analysis was performed to assess the percentage of bone in direct contact with the implant surface and a statistical analysis of the results was performed. Results: In the samples analyzed 4 weeks after implantation, the percentage of bone tissue in direct contact with the implant surface for the four groups were 57.66±24.39% (N), 58.62±20.37% (N+PRGF), 70.82±20.34 % (N+M) and 33.07±5.49% (C). In the samples with 8 weeks of implantation time, the percentage of bone in direct contact was 63.35±27.69% (N), 58.42±24.77% (N+PRGF), 78.02±15.13% (N+M) and 40.28±27.32% (C). In terms of the percentage of bone contact, groups N and N+M presented statistically significant differences from group C in the 4‐week trial test (P<0.05; ANOVA). For the 8‐week results, only group N+M showed statistically significant differences when compared with group C (P<0.05; ANOVA). Conclusion: In conclusion, the NuOss^? granules/RCM⁶ membrane combination presented a percentage of bone contact with the implant surface statistically greater than in the other groups. To cite this article:
Guerra I, Branco FM, Vasconcelos M, Afonso A, Figueiral H, Zita R. Evaluation of implant osseointegration with different regeneration techniques in the treatment of bone defects around implants: an experimental study in a rabbit model.
Clin. Oral Impl. Res. 22 , 2011; 314–322.
doi: 10.1111/j.1600‐0501.2010.02002.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     

Effects of growth hormone on initial bone formation around dental implants: a dog study

Objective: The aim of this study was to evaluate the effects of topical application of growth hormone (GH) on the osteointegration of dental implants in dogs at 5 and 8 weeks after surgery. Materials and methods: Mandibular premolars and molars were extracted from 12 Beagle dogs. Four screw implants were placed in each mandible. Before implant placement, 4 IU of GH were applied to the test sites (TS); no treatment was applied to control sites (CS). Morphometric parameters, bone‐to‐implant contact (BIC), peri‐implant connective tissue, interthread bone and newly formed bone were measured. The Student's t‐test for was used for statistical analysis of data obtained. Results: After 5 weeks of treatment, BIC values varied slightly between 34.33 ± 2.35% (CS) and 35.76 ± 2.96% (TS). Interthread bone tissue was 64.08 ± 8.68 at CS and 72.86 ± 2.93 at TS, with statistical significance (P<0.05). Bone neoformation was 72.53 ± 4.54 at the CS and 80.74 ± 1.65 for the GH group, these being statistically significant differences (P<0.05). After 8 weeks, BIC had slightly increased for the GH group (36.47 ± 3.09 vs. 39.61 ± 2.34). Interthread bone was 80.57 ± 2.28 at the CS and 82.58 ± 2.44 at the GH site, which was statistically significant. Bone neoformation was 88.09 ± 1.38 at CS and 91.01 ± 1.52 at TS, showing statistical significance (P<0.05). Conclusion: Topical application of 4 IU of GH like a biomimetic agent at the moment of implant placement has no significant effects on the BIC at 5 and 8 weeks, although bone neoformation and inter‐thread bone values did increase significantly. To cite this article:
Calvo‐Guirado JL, Mate‐Sanchez J, Delgado‐Ruiz R, Ramirez‐Fernández MP, Cutando‐Soriano A, Peña M. Effects of growth hormone on initial bone formation around dental implants: a dog study
Clin. Oral Impl. Res. 22 , 2011; 587–593.
doi: 10.1111/j.1600‐0501.2010.02007.x