Niklaus P. Lang

A systematic review of the survival and complication rates of fixed partial dentures (FPDs) after an observation period of at least 5 years

OBJECTIVES The objective of this systematic review was to assess the 5- and 10-year survival of implant supported fixed partial dentures (FPDs) and to describe the incidence of biological and technical complications. METHODS An electronic MEDLINE search complemented by manual searching was conducted to identify prospective and retrospective cohort studies on FPDs with a mean follow-up time of at least 5 years. Patients had to have been examined clinically at the follow-up visit. Assessment of the identified studies and data abstraction was performed independently by two reviewers. Failure and complication rates were analyzed using random-effects Poisson regression models to obtain summary estimates of 5- and 10-year survival proportions. RESULTS The search provided 3844 titles and 560 abstracts. Full-text analysis was performed for 176 articles resulting in 21 studies that met the inclusion criteria. Meta-analysis of these studies indicated an estimated survival of implants in implant-supported FPDs of 95.4% (95 percent confidence interval (95% CI): 93.9-96.5%) after 5 and 92.8% (95% CI: 90-94.8%) after 10 years. The survival rate of FPDs supported by implants was 95% (95% CI: 92.2-96.8%) after 5 and 86.7% (95% CI: 82.8-89.8%) after 10 years of function. Only 61.3% (95% CI: 55.3-66.8%) of the patients were free of any complications after 5 years. Peri-implantitis and soft tissue complications occurred in 8.6% (95% CI: 5.1-14.1%) of FPDs after 5 years. Technical complications included implant fractures, connection-related and suprastructure-related complications. The cumulative incidence of implant fractures after 5 years was 0.4% (95% CI: 0.1-1.2%). After 5 years, the cumulative incidence of connection-related complications (screw loosening or fracture) was 7.3% and 14% for suprastructure-related complications (veneer and framework fracture). CONCLUSION Despite a high survival of FPDs, biological and technical complications are frequent. This, in turn, means that substantial amounts of chair time have to be accepted by the clinician following the incorporation of implant-supported FPDs. More studies with follow-up times of 10 and more years are needed as only few studies have described the long-term outcomes.

Comparative biology of chronic and aggressive periodontitis vs. peri‐implantitis

This review was undertaken to address the similarities and dissimilarities between the two disease entities of periodontitis and peri-implantitis. The overall analysis of the literature on the etiology and pathogenesis of periodontitis and peri-implantitis provided an impression that these two diseases have more similarities than differences. First, the initiation of the two diseases is dependent on the presence of a biofilm containing pathogens. While the microbiota associated with periodontitis is rich in gram-negative bacteria, a similar composition has been identified in peri-implant diseases. However, increasing evidence suggests that S. aureus may be an important pathogen in the initiation of some cases of peri-implantitis. Further research into the role of this gram-positive facultative coccus, and other putative pathogens, in the development of peri-implantitis is indicated. While the initial host response to the bacterial challenge in peri-implant mucositis appears to be identical to that encountered in gingivitis, persistent biofilm accumulation may elicit a more pronounced inflammatory response in peri-implant mucosal tissues than in the dentogingival unit. This may be a result of structural differences (such as vascularity and fibroblast-to-collagen ratios). When periodontitis and peri-implantitis were produced experimentally by applying plaque-retaining ligatures, the progression of mucositis to peri-implantitis followed a very similar sequence of events as the development of gingivitis to periodontitis. However, some of the peri-implantitis lesions appeared to have periods of rapid progression, in which the infective lesion reached the alveolar bone marrow. It is therefore reasonable to assume that peri-implantitis in humans may also display periods of accelerated destruction that are more pronounced than that observed in cases of chronic periodontitis. From a clinical point of view the identified and confirmed risk factors for periodontitis may be considered as identical to those for peri-implantitis. In addition, patients susceptible to periodontitis appear to be more susceptible to peri-implantitis than patients without a history of periodontitis. As both periodontitis and peri-implantitis are opportunistic infections, their therapy must be antiinfective in nature. The same clinical principles apply to debridement of the lesions and the maintenance of an infection-free oral cavity. However, in daily practice, such principles may occasionally be difficult to apply in peri-implantitis treatment. Owing to implant surface characteristics and limited access to the microbial habitats, surgical access may be required more frequently, and at an earlier stage, in periimplantitis treatment than in periodontal therapy. In conclusion, it is evident that periodontitis and peri-implantitis are not fundamentally different from the perspectives of etiology, pathogenesis, risk assessment, diagnosis and therapy. Nevertheless, some difference in the host response to these two infections may explain the occasional rapid progression of peri-implantitis lesions. Consequently, a diagnosed peri-implantitis should be treated without delay.

Clinical experience with one-stage, non-submerged dental implants.

This review article describes the scientific documentation of one-stage, non-submerged dental implants. In the past 25 years, numerous in vivo studies have demonstrated that non-submerged titanium implants achieve osseointegration as predictable as that of submerged titanium implants. This observation was confirmed in prospective clinical studies, mostly done with the ITI® Dental Implant System. ITI implants have been widely documented for up to 10 years of prospective follow-up at various centers. All studies showed success rates well above 90%. In summary, the non-submerged approach is a true alternative to the original healing modality with submerged titanium implants. The non-submerged approach offers several clinical advantages: (i) the avoidance of a second surgical procedure and less chair time per patient, resulting in overall reduced treatment cost; (ii) the lack of a microgap at the bone crest level, leading to less crestal bone during healing and resulting in a more favorable crown-to-implant length ratio; and (iii) a simplified prosthetic procedure, presenting an ideal basis for cemented implant restorations. Due to these significant clinical advantages, the non-submerged approach will become more important in implant dentistry in the near future, particularly in implant sites without esthetic priority.

A prospective, randomized‐controlled clinical trial to evaluate bone preservation using implants with different geometry placed into extraction sockets in the maxilla

AIM The primary objective of this study was to determine the association between the size of the void established by using two different implant configurations and the amount of buccal/palatal bone loss that occurred during 16 weeks of healing following their installation into extraction sockets. MATERIAL AND METHODS The clinical trial was designed as a prospective, randomized-controlled parallel-group multicenter study. Adults in need of one or more implants replacing teeth to be removed in the maxilla within the region 15-25 were recruited. Following tooth extraction, the site was randomly allocated to receive either a cylindrical (group A) or a tapered implant (group B). After implant installation, a series of measurements were made to determine the dimension of the ridge and the void between the implant and the extraction socket. These measurements were repeated at the re-entry procedure after 16 weeks. RESULTS The study demonstrated that the removal of single teeth and the immediate placement of an implant resulted in marked alterations of the dimension of the buccal ridge (43% and 30%) and the horizontal (80-63%) as well as the vertical (69-65%) gap between the implant and the bone walls. Although the dimensional changes were not significantly different between the two-implant configurations, both the horizontal and the vertical gap changes were greater in group A than in group B. CONCLUSIONS Implant placement into extraction sockets will result in significant bone reduction of the alveolar ridge.

Temporal dynamics of healing in rabbit cranial defects using guided bone regeneration

PURPOSE The objective of this study was to histologically evaluate the early stages of bone regeneration using rabbit calvaria defects in conjunction with guided tissue regeneration. MATERIALS A semilunar cutaneous-periosteal flap was raised on the forehead of four rabbits exposing the top of the skull. A standardized transosseous skull defect (> or = 15 mm in diameter) was made in the area of the right parietal bone with a rotating round bur. Care was taken not to damage the underlying dura. A flat expanded polytetrafluoroethylene (ePTFE) membrane was placed to cover the defect. The membrane was tightly adapted, extending at least 4 mm onto intact bone, and the flap was sutured. One, 2, 3, and 5 weeks later, the specimens were removed and processed using standard, undecalcified, hard-tissue histologic techniques. Contact radiographs were also taken. RESULTS Bone growth increased with time, starting at the borders of the defect. At 1 week, trabeculae of woven bone grew into the highly vascularized loose connective tissue occupying the defect. Two weeks postsurgery, isolated islands of new bone were detected in this connective tissue. Subsequently, neighboring small islands merged to form large islands. In later stages, the primary trabeculae of woven bone were reinforced by layers of regularly deposited lamellar bone. CONCLUSION Rabbit calvaria defects treated by guided tissue regeneration heal by ingrowth of woven bone from the defect margins and by formation of bony islands within the defect area. Bone healing showed the histophysiological characteristics of intramembranous bone.

Maxillary sinus floor elevation using the (transalveolar) osteotome technique with or without grafting material. Part I: Implant survival and patients' perception.

OBJECTIVES To analyze the survival and success rates of implants installed utilizing the (transalveolar) osteotome technique, to compare peri-implant soft tissue parameters and marginal bone levels of osteotome-installed implants with implants placed using standard surgical procedures, and to evaluate patient-centered outcomes. MATERIAL AND METHODS During 2000 to 2005, 252 Straumann dental implants were inserted in 181 patients. The surgical technique was a modification of the original osteotome technique presented by Summers. In addition to the clinical examination, the patients were asked to give their perception of the surgical procedure, utilizing a visual analogue scale. RESULTS The cumulative survival rate of the osteotome-installed implants after a mean follow-up time of 3.2 years, was 97.4% (95% confidence intervals: 94.4-98.8%). From the 252 implants inserted, three were lost before loading and another three were lost in the first and second year. According to residual bone height the survival was 91.3% for implant sites with < or =4 mm residual bone height, and 90% for sites with 4 mm and 5 mm, when compared with that of 100% in sites with bone height of above 5 mm. According to implant length the survival rates were 100% for 12 mm, 98.7% for 10 mm, 98.7% for 8 mm and only 47.6% for 6 mm implants. Soft tissue parameters (pocket probing depth, probing attachment level, bleeding on probing and marginal bone levels) did not yield any differences between the osteotome-installed and the conventionally placed implants. More than 90% of the patients were satisfied with the implant therapy and would undergo similar therapy again if necessary. The cost associated with implant therapy was considered to be justified. CONCLUSION In conclusion, the osteotome technique was a reliable method for implant insertion in the posterior maxilla, especially at sites with 5 mm or more of preoperative residual bone height and a relatively flat sinus floor.

Principles in prevention of periodontal diseases Consensus report of group 1 of the 11th European Workshop on Periodontology on effective prevention of periodontal and peri-implant diseases

AIMS In spite of the remarkable success of current preventive efforts, periodontitis remains one of the most prevalent diseases of mankind. The objective of this workshop was to review critical scientific evidence and develop recommendations to improve: (i) plaque control at the individual and population level (oral hygiene), (ii) control of risk factors, and (iii) delivery of preventive professional interventions. METHODS Discussions were informed by four systematic reviews covering aspects of professional mechanical plaque control, behavioural change interventions to improve self-performed oral hygiene and to control risk factors, and assessment of the risk profile of the individual patient. Recommendations were developed and graded using a modification of the GRADE system using evidence from the systematic reviews and expert opinion. RESULTS Key messages included: (i) an appropriate periodontal diagnosis is needed before submission of individuals to professional preventive measures and determines the selection of the type of preventive care; (ii) preventive measures are not sufficient for treatment of periodontitis; (iii) repeated and individualized oral hygiene instruction and professional mechanical plaque (and calculus) removal are important components of preventive programs; (iv) behavioural interventions to improve individual oral hygiene need to set specific Goals, incorporate Planning and Self monitoring (GPS approach); (v) brief interventions for risk factor control are key components of primary and secondary periodontal prevention; (vi) the Ask, Advise, Refer (AAR) approach is the minimum standard to be used in dental settings for all subjects consuming tobacco; (vii) validated periodontal risk assessment tools stratify patients in terms of risk of disease progression and tooth loss. CONCLUSIONS Consensus was reached on specific recommendations for the public, individual dental patients and oral health care professionals with regard to best action to improve efficacy of primary and secondary preventive measures. Some have implications for public health officials, payers and educators.

Surgical and nonsurgical periodontal therapy. Learned and unlearned concepts

This review aims to highlight concepts relating to nonsurgical and surgical periodontal therapy, which have been learned and unlearned over the past few decades. A number of treatment procedures, such as gingival curettage and aggressive removal of contaminated root cementum, have been unlearned. Advances in technology have resulted in the introduction of a range of new methods for use in nonsurgical periodontal therapy, including machine-driven instruments, lasers, antimicrobial photodynamic therapy and local antimicrobial-delivery devices. However, these methods have not been shown to offer significant benefits over and above nonsurgical debridement using hand instruments. The method of debridement is therefore largely dependent on the preferences of the operator and the patient. Recent evidence indicates that specific systemic antimicrobials may be indicated for use as adjuncts to nonsurgical debridement in patients with advanced disease. Full-mouth disinfection protocols have been proven to be a relevant treatment option. We have learned that while nonsurgical and surgical methods result in similar long-term treatment outcomes, surgical therapy results in greater probing-depth reduction and clinical attachment gain in initially deep pockets. The surgical technique chosen seems to have limited influence upon changes in clinical attachment gain. What has not changed is the importance of thorough mechanical debridement and optimal plaque control for successful nonsurgical and surgical periodontal therapy.

Isolation of Periodontal Species After Guided Tissue Regeneration

One advanced localized periodontal lesion in each of 10 patients was treated using the guided tissue regeneration procedure. Six weeks after placement of expanded polytetrafluoroethylene (ePTFE) membranes, microbial samples were taken from each treated site and the membranes were removed. Six weeks later the cases were re-evaluated. They had all healed successfully with varying amounts of gain of clinical attachment. Gram-negative, anaerobic rods were found in all samples and made up 31% of all organisms cultivated. In 1 patient, Porphyromonas gingivalis was found in a proportion of 17.5%. Six of the other 9 patients harbored Prevotella intermedia (mean proportion 21.3%) and 6 Prevotella melaninogenica (6.8%). Fusobacterium and Capnocytophaga were also frequently found. The results demonstrate that ePTFE membranes are frequently colonized by periodontal microorganisms. The importance of bacterial colonization on clinical success is presently not known. Further studies are needed to determine the effect of the presence or absence of putative pathogens during guided tissue regeneration. J Periodontol 1993; 64:1171-1175.

Effects of decontamination and implant surface characteristics on re-osseointegration following treatment of peri-implantitis.

BACKGROUND Although considerable bone fill may occur following treatment of peri-implantitis, re-osseointegration appears to be limited and unpredictable. OBJECTIVES To evaluate the effects of various decontamination techniques and implant surface configurations on re-osseointegration of contaminated dental implants. MATERIAL AND METHODS Three months after tooth extraction, implants consisting of a basal part and an exchangeable intraosseous implant cylinder (EIIC) were placed in the mandibles of dogs. The EIIC was machined (M), sandblasted and acid-etched (SLA), or titanium plasma sprayed (TPS). Ligature-induced peri-implantitis was initiated 8 weeks post-implantation and lasted until bone loss reached the junction of the two implant parts. Three treatment modalities were applied: (T1) the EIIC was exchanged for a pristine EIIC; (T2) the EIIC was sprayed in situ with saline; and (T3) the EIIC was removed, cleansed outside the mouth by spraying with saline, steam-sterilized, and remounted. A collagen barrier was placed over each fixture, and 3 months later, samples were processed for histology and histomorphometry. RESULTS T2 revealed the highest bone-to-implant contact (BIC) level (significantly better than T1 and T3). T2 also yielded the highest bone crest level (significantly better than T1), followed by T3 (significantly better than T1). SLA showed the highest BIC level (significantly better than M), followed by TPS. There were no statistically significant differences in bone crest height between implant types. CONCLUSIONS Both SLA implants and in situ cleansing resulted in the best re-osseointegration and bone fill of previously contaminated implants.