Is Metal Particle Release Associated with Peri-implant Bone Destruction? An Emerging Concept.

Peri-implant diseases affecting the surrounding structures of endosseous dental implants include peri-implant mucositis and peri-implantitis. The prevalence of peri-implantitis ranges between 15% and 20% after 10 y, highlighting the major challenge in clinical practice in the rehabilitation of dental implant patients. The widespread nature of peri-implant bone loss poses difficulties in the management of biological complications affecting the long-term success of osseointegrated implant reconstructions. Metal and titanium particles have been detected in peri-implant supporting tissues. However, it remains unclear what mechanisms could be responsible for the elicitation of particle and ion release and whether these released implant-associated materials have a local and/or systemic impact on the peri-implant soft and hard tissues. Metal particle release as a potential etiologic factor has been intensively studied in the field of orthopedics and is known to provoke aseptic loosening around arthroplasties and is associated with implant failures. In dental medicine, emerging information about metal/titanium particle release suggests that the potential impact of biomaterials at the abutment or bone interfaces may have an influence on the pathogenesis of peri-implant bone loss. This mini-review highlights current evidence of metal particle release around dental implants and future areas for research.

The influence of cortical bone perforation on guided bone regeneration in humans.

The purpose of this study was to evaluate the effect of cortical bone perforation on angiogenesis and osteogenesis of the augmented ridge in guided bone regeneration. Eighteen patients who had osseous defects in the mandible were selected. In the test group (n=9), alveolar cortical bone in the area of regeneration was perforated. No decortication was performed in the control group (n=9). Subsequently, defects were augmented by guided bone regeneration using resorbable membrane and bovine bone. After a healing period of 7 months, trephine cores were harvested for histological and histomorphometric analysis of the grafted areas. Histomorphometry demonstrated that the amount of newly formed bone in the test group (27.8%) was greater than that in the control group (25.3%), but the difference was not statistically significant (P=0.13). However, the mean number of microvessels in the test group was significantly higher than that in the control group (P=0.01). This study found that cortical bone perforation favourably affects the amount of new bone formation in the grafted sites after 7 months of healing. Cortical bone perforation significantly increase number of new vessels (angiogenesis) of the regenerated bone. Further randomized clinical trials are required to confirm these results.

The role of bone decortication in enhancing the results of guided bone regeneration: a literature review.

BACKGROUND: Bone decortication is often performed as part of a guided bone regeneration (GBR) procedure. The biologic rationale for decortication of bone is to allow progenitor cells easy access to a GBR-treated site and to facilitate prompt angiogenesis. It also may enhance the physical connection between a bone graft and a recipient site. However, the concept of decortication prior to a GBR procedure is controversial because there are no human clinical trials to support its effectiveness, and there are opposing points of view derived from animal studies regarding its usefulness. METHODS: The literature was assessed to determine whether there are enough data to validate the rationale for using decortication of bone as an integral part of GBR procedures. Eight searches were performed seeking controlled clinical trials that addressed the ability of decortication to enhance GBR. RESULTS: Three controlled animal clinical trials were found that supported the use of decortication prior to performing GBR. Two controlled animal clinical trials were located that indicated decortication did not improve GBR procedures. No human controlled clinical trial was identified that addressed the ability of decortication to alter GBR procedures. The literature addressing the capacity of decortication to affect onlay grafting or wound healing also provided mixed results. CONCLUSION: There is conflicting information and not enough clinical trials to make a definitive determination as to the merits of bone decortication prior to GBR procedures.

Clinical and radiographic evaluation of the papilla level adjacent to single-tooth dental implants. A retrospective study in the maxillary anterior region.

BACKGROUND: The regeneration of gingival papillae after single-implant treatment is an area of current investigation. This study was designed to determine: 1) whether the distance from the base of the contact point to the crest of the bone would correlate with the presence or absence of interproximal papillae adjacent to single-tooth implants, and 2) whether the surgical technique at uncovering influences the outcome. METHODS: A clinical and radiographic retrospective evaluation of the papilla level around single dental implants and their adjacent teeth was performed in the anterior maxilla in 26 patients restored with 27 implants. Six months after insertion, 17 implants were uncovered with a standard technique, while 10 implants were uncovered with a technique designed to generate papilla-like formation around dental implants. Fifty-two papillae were available for clinical and radiographic evaluation. The presence or absence of papillae was determined, and the effects of the following variables were analyzed: the influence of the 2 surgical techniques; the vertical relation between the papilla height and the crest of bone between the implant and adjacent teeth; the vertical relation between the papilla level and the contact point between the crowns of the teeth and the implant; and the distance from the contact point to the crest of bone. RESULTS: When the measurement from the contact point to the crest of bone was 5 mm or less, the papilla was present almost 100% of the time. When the distance was > or = 6 mm, the papilla was present 50% of the time or less. The mean distance between the crest of bone and the most coronal papilla level (interproximal soft tissue height) was 3.85 mm (SD = 1.04). When comparing the conventional and modified surgical technique, the relation shifted from 3.77 mm (SD = 1.01) to 4.01 mm (SD = 1.10), respectively. CONCLUSIONS: These results clearly show the influence of the bone crest on the presence or absence of papillae between implants and adjacent teeth. The data also show a positive influence for the modified surgical technique, aimed at reconstructing papillae at the implant uncovering.

The implant periapical lesion: four case reports and review of the literature.

Postoperative complications have been identified with implant failure in conjunction with the increased use of root-type implant restorations. The failure of osseointegrated dental implants primarily occurs as a result of peri-implantitis and occlusal overload. Less frequently reported failures, however, have been attributed to implant periapical lesions. The etiology and treatment modalities for such lesions have been speculated throughout the literature. This article discusses possible etiologies of and treatment for implant periapical lesions based on the existing literature and four case reports.

Digital shade analysis and verification: a case report and discussion.

Shade analysis and selection requires the accurate and objective evaluation of hue, chroma, value, characterization, and translucency. Conventional shade analysis techniques using shade tabs often result in the subjective analysis and miscommunication of color. Digital shade analysis systems have been designed to eliminate the subjectivity of color analysis and provide exact information for laboratory buildup and fabrication. The advent of digital shade analysis can facilitate the precise and uniform fabrication of aesthetic restorations by technicians at all levels of color expertise.

A prospective 2-year clinical evaluation of overdentures attached to nonsplinted implants utilizing ERA attachments.

Edentulism is a major oral healthcare issue for an ever-increasing older population in the United States. Most previous studies examined the success of overdentures supported by splinted implants utilizing clip bars and other types of attachments. This longitudinal study of 10 consecutive patients involves mandibular overdentures supported by nonsplinted implants with ERA attachments. Two-year results indicate that nonsplinted implants can be successfully used with ERA attachments to support overdentures. Each patient reported increased satisfaction with comfort, chewing, retention, and phonetics with the implant-assisted ERA-retained overdenture.

A comparative study utilizing open flap debridement with and without enamel matrix derivative in the treatment of periodontal intrabony defects: a 12-month re-entry study.

BACKGROUND: Previous studies have demonstrated that enamel matrix derivative (EMD) has the ability to improve clinical parameters when used to treat intraosseous defects. The purpose of the present study was to compare at 12 months postsurgery sites treated with open flap debridement (OFD) alone to those treated with OFD and EMD. METHODS: Twenty-three subjects with at least 2 intrabony defects were chosen. Fifty-three defects received EMD in conjunction with OFD. Thirty-one defects in these same 23 subjects were treated with OFD alone. Stents were fabricated to serve as fixed reference points. Re-entries were performed at least 1 year after initial surgery. Soft tissue measurements were recorded prior to initial surgery and prior to re-entry for gingival (GI) and plaque (PI) indices, probing depth (PD), gingival margin position, and clinical attachment level (CAL). Hard tissue measurements were recorded during the initial and re-entry surgery for level of crestal bone and depth of defect. Statistical analysis was conducted using the method of generalized estimating equations to determine changes in GI, PI, PD, CAL, fill of the osseous defect, and crestal resorption. Percent of defect fill was also calculated. RESULTS: In all categories, treatment with EMD (test) was superior to treatment without EMD (control). Average PI and GI were not significantly different either initially or prior to re-entry. The average PD reduction was 2.7 mm greater with EMD than controls. The average CAL gains were 1.5 mm greater, and the average fill of osseous defect 2.4 mm greater with EMD than controls. The average percent of defect fill after adjusting for crestal bone loss was more than 3 times greater for EMD versus control-treated sites (74% defect fill with EMD versus 23% defect fill for control sites). CONCLUSIONS: This study indicates that treatment of periodontal intraosseous defects with EMD is clinically superior to treatment without EMD (open flap debridement) in every parameter evaluated. Re-entry data demonstrate that percent fill of osseous defects treated with EMD compares favorably with the treatment results utilizing bone grafts or membrane barriers, according to published literature.

Alumina ceramic implant abutments used for single-tooth replacement: a prospective 1- to 3-year multicenter study.

PURPOSE: The aim of the study was to compare results after 1 and 3 years when single crowns supported by CerAdapt (test) ceramic abutments or CeraOne (control) titanium abutments were loaded. MATERIALS AND METHODS: The material was divided into two groups: in group A, 69 (34 test, 35 control) abutments/crowns from all involved clinics were followed for 1 year; and in group B, 20 (10 test, 10 control) abutments/crowns from one of the clinics were followed for 3 years. RESULTS: No implant failed, giving a cumulative success rate of 100% for the implants. Two CerAdapt abutments in group A fractured, giving a cumulative success rate of 93% for the CerAdapt and 100% for the CeraOne abutments after 1 year. No abutment failed in group B, giving a cumulative success rate of 100% both for the CerAdapt and the CeraOne abutments between 1 and 3 years. The CerAdapt fractures might have been due to the fact that the abutments were impaired through too-extensive preparation and/or had been exposed to a too-high bending moment. Almost no marginal bone loss was recorded, indicating a stable bone situation both at CerAdapt and CeraOne abutments on single-tooth implants. Healthy conditions, with a relatively stable level of the periimplant mucosa in relation to the abutment/crown, were recorded for soft tissues both at CerAdapt and CeraOne abutments. Both clinicians and patients rated the esthetic result as excellent for practically all cases. CONCLUSION: The results demonstrate the esthetic possibilities and the safety of single-tooth replacement when accepted treatment concepts are followed and documented components are used. The tested abutments worked well, although the fractured CerAdapt abutments indicate that ceramic abutments are more sensitive to handling procedures than the titanium abutments.

Histologic response to intraligament injections using a computerized local anesthetic delivery system. A pilot study in mini-swine.

BACKGROUND: Intraligamentary (periodontal ligament) injection has been used to locally control pain with minimal anesthetic dose. The purpose of the present study was to determine the histologic effect of using a computer-controlled local anesthesia delivery system (CCLADS) for the administration of a periodontal ligament injection in the mini-swine model system. METHODS: Thirty-two sites in 3 mini-swine pigs with healthy periodontium were selected. Each site was notched on the mesial-lingual line angle of the tooth to allow a reference for needle placement and provide a histologic marker. An anesthetic cartridge was used with a 30-gauge needle attached to the handpiece of the CCLADS. This provided a controlled flow rate for 2 minutes. The control sites were treated with the same needle in place for 20 seconds. The animals were sacrificed and provided observation periods of 1 hour, 1, 4, 7, 21, and 49 days. Specimens were stained with hematoxylin and eosin and trichrome. RESULTS: Twenty-four hours after injection, limited localized inflammation was present. By 7 days, the ligament appeared within normal limits. Apical migration of the junctional epithelium extended to the apical limit of the notch and was similar in test and control specimens. CONCLUSIONS: Within the limits of this study, the histologic results showed that tissue responses following intraligament injections using a CCLADS demonstrated limited inflammatory responses within the first 24 hours, which abated by 7 days postinjection. Similar migration of the junctional epithelium was seen in test and control specimens and was probably related to tooth injury rather than anesthetic injections. Further investigations are warranted using CCLADS to determine whether clinical benefits will translate in the human model system.

Gingival recession around implants: a 1-year longitudinal prospective study.

A longitudinal study was performed, which measured the soft tissue around implants following surgery, to determine if a predictable pattern of soft tissue changes could be identified. This study evaluated 63 implants in 11 patients. Baseline measurements were recorded at stage 2 surgery in 2-stage implant systems, and at stage 1 surgery in the 1-stage system. Subsequent measurements were recorded at 1 week, 1 month, 3 months, 6 months, 9 months, and 1 year after baseline measurements. The majority of the recession occurred within the first 3 months, and 80% of all sites exhibited recession on the buccal. It is therefore recommended that one wait 3 months for the tissue to stabilize before either selecting a final abutment or making a final impression. As a general rule, one can anticipate approximately 1 mm of recession from the time of abutment connection surgery. A comparison of this study's results with data recorded in previously reported studies reveals clinically significant trends in the nature of soft tissue healing.

The effect of inter-implant distance on the height of inter-implant bone crest.

BACKGROUND: The biologic width around implants has been well documented in the literature. Once an implant is uncovered, vertical bone loss of 1.5 to 2 mm is evidenced apical to the newly established implant-abutment interface. The purpose of this study was to evaluate the lateral dimension of the bone loss at the implant-abutment interface and to determine if this lateral dimension has an effect on the height of the crest of bone between adjacent implants separated by different distances. METHODS: Radiographic measurements were taken in 36 patients who had 2 adjacent implants present. Lateral bone loss was measured from the crest of bone to the implant surface. In addition, the crestal bone loss was also measured from a line drawn between the tops of the adjacent implants. The data were divided into 2 groups, based on the inter-implant distance at the implant shoulder. RESULTS: The results demonstrated that the lateral bone loss was 1.34 mm from the mesial implant shoulder and 1.40 mm from the distal implant shoulder between the adjacent implants. In addition, the crestal bone loss for implants with a greater than 3 mm distance between them was 0.45 mm, while the implants that had a distance of 3 mm or less between them had a crestal bone loss of 1.04 mm. CONCLUSIONS: This study demonstrates that there is a lateral component to the bone loss around implants in addition to the more commonly discussed vertical component. The clinical significance of this phenomenon is that the increased crestal bone loss would result in an increase in the distance between the base of the contact point of the adjacent crowns and the crest of bone. This could determine whether the papilla was present or absent between 2 implants as has previously been reported between 2 teeth. Selective utilization of implants with a smaller diameter at the implant-abutment interface may be beneficial when multiple implants are to be placed in the esthetic zone so that a minimum of 3 mm of bone can be retained between them at the implant-abutment level.

Three-year post-placement survival of implants mobile at placement.

BACKGROUND: Although rigid fixation of endosseous implants at the time of placement is generally thought to be a prerequisite for successful osseointegration, the Dental implant Clinical Research Group (DICRG) of the Department of Veterans Affairs has reported on implants that integrated despite being mobile at placement. The present study examines the frequency of osseointegration and the 36-month post-placement survival of implants mobile at placement in a prospective, multicenter, longitudinal clinical study of more than 3,000 implants conducted by the DICRG. METHODS: A total of 3,111 implants of 6 different designs were placed in all jaw regions in more than 800 patients at 32 study centers. At the time of this report, 2,770 of these implants had been followed for 36 months post-placement. They included 89 implants that were mobile at placement. Data for demographic variables, implant coating, bone quality, incision type, bone augmentation, and antibiotic usage were recorded. An electronic hand-held probe was used to measure mobility at uncovering and at regular follow-up intervals. RESULTS: Eighty-nine of 2,770 inserted implants were mobile at placement. Results are reported for two periods: from placement to 36 months and from prosthetic loading to 36 months. The latter method eliminated early failures and resulted in substantially higher scores for both mobile implants at placement (95.9% survival from prosthetic loading to 36 months post-placement versus 79.8% from placement to 36 months) and implants not mobile at placement (98.4% versus 93.4%). Mobility at placement was significant to 3-year survival (P < 0.001). Hydroxyapatite (HA) coating improved the performance of implants mobile at placement (91.8% for HA-coated versus 53.6% for non-HA) and those not mobile at placement (97.2% for HA-coated versus 87.4% for non-HA). Radiographic findings suggested that crestal bone response around implants which were mobile versus immobile at placement was similar. CONCLUSIONS: Although implant stability at the time of placement is clearly desirable as seen in the superior 3-year survival of stable implants, it may not be an absolute prerequisite to osseointegration or to long-term survival. Several factors may influence the decision to remove or replace a mobile implant. HA-coating significantly improved the performance of both mobile and immobile implants at placement to 3 years post-placement (P < 0.001).

Histologic and clinical comparison of bilateral sinus floor elevations with and without barrier membrane placement in 12 patients: Part 3 of an ongoing prospective study.

In 1993 the Department of Implant Dentistry at New York University College of Dentistry began a long-term clinical, histologic, histomorphometric, and radiographic study of the sinus elevation procedure. One of the parameters under evaluation in this study is the effect of barrier membrane placement on the creation of vital bone in the grafted sinus cavity. This report presents a histologic and histomorphometric evaluation of healing with and without the placement of an expanded polytetrafluoroethylene (e-PTFE) barrier membrane over the lateral window at the time of sinus grafting. The data were collected from 12 patients who underwent bilateral sinus elevation surgery. In each of these 12 patients the same grafting material was used in both sinuses, making the presence or absence of an e-PTFE barrier membrane the only controlled variable. Under the conditions of this study, the results indicate that (1) placement of the barrier membrane tends to increase vital bone formation; (2) placement of a barrier membrane has a positive effect on implant survival; and (3) membrane placement should be considered for all sinus elevation procedures.

Human histologic evidence of integration of functionally loaded hydroxyapatite-coated implants placed simultaneously with sinus augmentation: a case report 2 1/2 years postplacement.

This article histologically and clinically presents a case report showing two retrieved implants that were placed simultaneously at the time of the antral augmentation. These implants were retrieved 2.5 years after placement and 2 years after loading. To our knowledge, this is the first human histological case report of implants that were simultaneously placed with a sinus lift and loaded.