Comparison of Push‐In versus Pull‐Out Tests on Bone‐Implant Interfaces of Rabbit Tibia Dental Implant Healing Model

Purpose: This study aimed to investigate whether push‐in and pull‐out tests measure mechanical properties of the bone–implant interface differently, and which test is more sensitive to changes over the healing period. Materials and Methods: Two identical self‐threading dental implants (3.3 × 8.5 mm) were placed in medial surface of the proximal condyles of left and right tibias of 20 rabbits (40 implants total). Five rabbits each were sacrificed after 1, 4, 8, and 12 weeks of healing. Push‐in test was performed on one side's tibia implant and pull‐out on the other side's implant, at a rate of 6 mm/min. Primary and secondary implant stabilities and tibia weight were measured on all implants. Results: The push‐in test generated significantly higher failure load (p = .0001; 530 N vs 279 N), lower displacement at failure (p = .0003; 0.436 mm vs 0.680 mm), and higher interface stiffness (p < .0001; 1,641 N/mm vs 619 N/mm) than pull‐out test. Failure load, stiffness, and secondary implant stability were significantly higher for longer compared with shorter healing periods, while displacement, tibia weight, and primary stability were not. Failure load and stiffness differed significantly for four healing times for the push‐in but not for the pull‐out test. Failure load was significantly correlated with secondary implant stability for both push‐in (r = 0.66) and pull‐out (r = 0.48) tests, but stiffness was significantly correlated with secondary stability only for the push‐in test (r = 0.72; pull‐out test r = 0.40). Conclusion: The push‐in test appeared more sensitive than pull‐out to changes in mechanical properties at bone–implant interfaces during healing in rabbit tibia model.     

Microbial Colonization of the Peri‐Implant Sulcus and Implant Connection of Implants Restored With Cemented Versus Screw‐Retained Superstructures: A Cross‐Sectional Study

Background: The aim of this study is to investigate peri‐implant and intraconnection microflora of healthy implants restored with cemented and screwed superstructures. Methods: Patients with two to three implants restored with cemented or screwed restorations and 5 years of follow‐up were recruited. Samples were taken from peri‐implant sulci, adjacent teeth, and the inner portion of connections. Prevalence of positive sites and bacterial loads for 10 microorganisms were obtained with quantitative real‐time polymerase chain reaction. Implant connection permeability to the studied microorganisms was estimated using a standardized bacterial contamination index. Statistical analysis was performed using a generalized estimating equations model, Wald χ² test, and the least significant difference test. Results: The final sample consisted of 18 patients (55 implants) in the cemented group and 22 patients (46 implants) in the screw‐retained group. Regarding prevalence of positive sites, significant differences between groups were only found for Tannerella forsythia, which was 8.7 times more frequent at peri‐implant sulci of cemented than screw‐retained prostheses. Bacterial loads of Porphyromonas gingivalis, T. forsythia, Parvimonas micra, and total bacterial load were significantly higher at peri‐implant sulci for the cemented group; at the inner portion of connections, values were significantly higher for P. micra and Fusobacterium nucleatum for the screw‐retained group. Contamination index values demonstrated higher permeability to most microbes in the cemented group. Conclusions: Internal implant surfaces were microbiologically contaminated for both cemented and screw‐retained superstructures. Differences were found between the two methods of prosthetic retention: the cemented group presented significantly higher bacterial loads in the peri‐implant sulcus but significantly lower bacterial loads at the inner portion of the implant connection.     

The Peri‐Implantitis: Implant Surfaces,Microstructure, and Physicochemical Aspects

There are two ways of looking at secondary failures of osseointegration; one is to reflect on possible causes for the failure, the other focuses on the pathology per se. In the first case, background factors such as mechanical trauma (adverse loading) or inflammations/infections are being discussed as the cause of failure. Then peri‐implantitis is a term reserved for implant disturbance due to inflammation/infections only. However, irrespective of the original reason for the failure being adverse loading or inflammation/infection, the end result with bone resorption and inflammation may be very similar. Hence, in the present article, an alternative outlook has been chosen. Trigerring factors for peri‐implantitis are generally gathered under four categories: lesions of peri‐implant attachment, presence of aggressive bacteria, excessive mechanical stress, and corrosion. If only one of these factors would start a chain reaction leading to lesions, then the other factors may combine to worsen the condition. With other words, peri‐implantitis is a general term dependent on a synergy of several factors, irrespective of the precise reason for first triggering off symptoms.     

Long‐Term Evaluation of Periodontal Parameters and Implant Outcomes in Periodontally Compromised Patients: A Systematic Review

Background : The aim of this systematic review is to evaluate the long‐term outcomes of patients with periodontitis submitted to periodontal therapy/maintenance and implant placement. Methods: Studies reporting clinical and/or long‐term implant outcomes from partially edentulous patients with periodontitis who were treated and followed periodontal maintenance for ≥5 years were considered eligible for the review. Screening of the articles, data extraction, and quality assessment were conducted independently and in duplicate. Results: Search of MEDLINE, EMBASE, and CENTRAL databases resulted in 959 papers, and of them 931 were excluded after title/abstract assessment. The full texts of 28 potentially eligible publications were screened, but only 10 studies met inclusion criteria. Most of the included studies (77.8%) presented a medium/high methodologic quality. The results demonstrated that patients with a diagnosis of periodontitis had satisfactory implant outcomes. Implant survival was high (92.1%) within studies reporting 10 years of follow‐up. Parameters related to probing depth, clinical attachment level, and bone loss around teeth increased the occurrence of peri‐implantitis and implant loss. Non‐attendance to periodontal maintenance and smoking habits were also associated with less favorable implant outcomes. Conclusions: This systematic review confirmed that implant therapy can be successfully used in patients with a diagnosis of periodontitis who underwent proper therapy and regular periodontal maintenance. Residual pockets, non‐attendance to the periodontal maintenance program, and smoking were considered to be negative factors for the long‐term implant outcomes.     

Surgical Reconstruction of Peri‐Implant Bone Defects with Prehydrated and Collagenated Porcine Bone and Collagen Barriers: Case Presentations

Background: Surgical reconstruction of peri‐implant defects is challenging and unpredictable due to, for example, the extent of the bone defect or the osteogenic potential of adjunctive materials used. Purpose: To study the healing capacity of a new bone xenograft material in the treatment of peri‐implant defects. Material and Methods: In three cases with advanced peri‐implant defects, flap surgery was performed. After thorough debridement including cleaning of the exposed implant surface, prehydrated and collagenated porcine bone (PCPB) particles were placed into the defect. A bioresorbable collagen barrier was adapted and placed over the defect and the flaps were relocated. After 6 and 12 months of healing, clinical and radiographic examinations were done. In one case, the surgical procedure was repeated 6 months postoperatively. One year after the second surgery, a bone biopsy was harvested and analyzed with histology. Results: All defects healed uneventfully. At 6 months, probing depths were reduced by 3–4 mm with no bleeding on probing or pus formation. At 12 months, healthy peri‐implant conditions were found. Intra‐oral radiographs showed gain of the marginal bone level by 2–4 mm. In the case where reconstructive surgery was repeated, histology showed osteoconductive properties as bone formation with typical osteoblastic seams was observed directly on the surface of the grafted particles. Conclusion: The presented cases show that PCPB have favorable properties enhancing bone regeneration in peri‐implant bone defects.     

Outcome of surgical treatment of peri-implantitis: results from a 2-year prospective clinical study in humans

Aim: The aim of the present study was to evaluate the outcome of a surgical procedure based on pocket elimination and bone re‐contouring for the treatment of peri‐implantitis. Material and methods: The 31 subjects involved in this study presented clinical signs of peri‐implantitis at one or more dental implants (i.e. ≥6 mm pockets, bleeding on probing and/or suppuration and radiographic evidence of ≥2 mm bone loss). The patients were treated with a surgical procedure based on pocket elimination and bone re‐contouring and plaque control before and following the surgery. At the time of surgery, the amount of bone loss at implants was recorded. Results: Two years following treatment, 15 (48%) subjects had no signs of peri‐implant disease; 24 patients (77%) had no implants with a probing pocket depth of ≥6 mm associated with bleeding and/or suppuration following probing. A total of 36 implants (42%) out of the 86 with initial diagnosis of peri‐implantitis presented peri‐implant disease despite treatment. The proportion of implants that became healthy following treatment was higher for those with minor initial bone loss (2–4 mm bone loss as assessed during surgery) compared with the implants with a bone loss of ≥5 mm (74% vs. 40%). Among the 18 implants with bone loss of ≥7 mm, seven were extracted. Between the 6‐month and the 2‐year examination, healthy implants following treatment tended to remain stable, while deepening of pockets was observed for those implants with residual pockets. Conclusion: The results of this study indicated that a surgical procedure based on pocket elimination and bone re‐contouring and plaque control before and following surgery was an effective therapy for treatment of peri‐implantitis for the majority of subjects and implants. However, complete disease resolution at the site level seems to depend on the initial bone loss at implants. Implants with no signs of peri‐implantitis following treatment tended to remain healthy during the 2‐year period, while a tendency for disease progression was observed for the implants that still showed signs of peri‐implant disease following treatment. To cite this article:
Serino G, Turri A. Outcome of surgical treatment of peri‐implantitis: results from a 2‐year prospective clinical study in humans.
Clin. Oral Impl. Res. 22 , 2011; 1214–1220.
doi: 10.1111/j.1600‐0501.2010.02098.x