Biologic width around titanium implants. A physiologically formed and stable dimension over time

Research in implant dentistry has mainly focused on hard tissue integration with much less data available with regards to soft tissue integration involving epithelium and connective tissue. In the present study, the implantogingival junction of unloaded and loaded non-submerged titanium implants has been analyzed histometrically in the canine mandible. In 6 foxhounds, 69 implants were placed. Dogs in the unloaded group were sacrificed 3 months after implant placement. Loaded implants were restored with gold crowns and those dogs were sacrificed after 3 months and 12 months of loading. Non-decalcified histologic sections were analyzed histometrically measuring the dimensions of the Sulcus Depth (SD), the Junctional Epithelium (JE), and the Connective Tissue Contact (CTC). Histometric evaluation revealed that significant changes within tissue compartments (SD, JE, CTC) occurred over time (P < 0.05). Sulcus Depth had a mean of 0.49 mm and 0.50 mm after 3 months and 6 months of healing, but after 15 months was 0.16 mm which was significantly different. Similarly, the length of the Junctional Epithelium after 3 months and 6 months of healing was 1.16 mm and 1.44 mm, respectively, and these values were significantly different from measurements taken after 15 months (1.88 mm). The area of Connective Tissue Contact showed a different pattern of change in that after 3 months of healing (1.36 mm) it was significantly different from the same area after 6 months and 15 months which were 1.01 mm and 1.05 mm, respectively. Interestingly, the sum of SD, JE, and CTC, forming the Biologic Width, did not change over the observation period (P > 0.05). These data indicate that the Biologic Width is a physiologically formed and stable structure over time in the case of non-submerged, one-piece titanium implants as evaluated histometrically under unloaded and loaded conditions. Dynamic changes did occur, however, within the overall Biologic Width dimension. Thus, the use of non-submerged, one-piece implants allow for stable overall peri-implant soft tissues as evaluated under loaded conditions for up to 12 months.     

Biologic Width around one- and two-piece titanium implants

Gingival esthetics around natural teeth is based upon a constant vertical dimension of healthy periodontal soft tissues, the Biologic Width. When placing endosseous implants, however, several factors influence periimplant soft and crestal hard tissue reactions, which are not well understood as of today. Therefore, the purpose of this study was to histometrically examine periimplant soft tissue dimensions dependent on varying locations of a rough/smooth implant border in one-piece implants or a microgap (interface) in two-piece implants in relation to the crest of the bone, with two-piece implants being placed according to either a submerged or a nonsubmerged technique. Thus, 59 implants were placed in edentulous mandibular areas of five foxhounds in a side-by-side comparison. At the time of sacrifice, six months after implant placement, the Biologic Width dimension for one-piece implants, with the rough/smooth border located at the bone crest level, was significantly smaller (P<0.05) compared to two-piece implants with a microgap (interface) located at or below the crest of the bone. In addition, for one-piece implants, the tip of the gingival margin (GM) was located significantly more coronally (P<0.005) compared to two-piece implants. These findings, as evaluated by nondecalcified histology under unloaded conditions in the canine mandible, suggest that the gingival margin (GM) is located more coronally and Biologic Width (BW) dimensions are more similar to natural teeth around one-piece nonsubmerged implants compared to either two-piece nonsubmerged or two-piece submerged implants.     

Biologic width changes around loaded implants inserted in different levels in relation to crestal bone: histometric evaluation in canine mandible

Objectives: The aim of the present study was to evaluate histometric changes around dental implants inserted at different levels in relation to the crestal bone, under different loading conditions. Material and methods: Thirty‐six implants were inserted in the edentulous mandible of six mongrel dogs. Each implant was assigned to an experimental group according to the distance from the top of the implant to the crestal bone: Bone Level (at the crestal bone level), Minus 1 (1 mm below the crestal bone) or Minus 2 group (2 mm below the crestal bone). Each hemimandible was submitted to a loading protocol: conventional or immediate restoration. After 90 days, the animals were killed. Specimens were processed, and measurements were performed concerning the length of soft and hard peri‐implant tissues. Data were analyzed using ANOVA and Student's t test (α=5%). Results: Among conventionally restored sites, the distance from the most coronal position of soft tissue margin (PSTM) and first bone–implant contact (fBIC) was greater for Minus 2 than for Bone Level and Minus 1 sites (P=0.03), but significant differences were not observed among immediately restored sites. Differences among groups were not observed concerning the PSTM, and the distance from the implant–abutment junction to fBIC. Greater amounts of lateral bone loss were observed for conventionally than for immediately restored sites (P=0.006). Conclusions: These findings suggest that the apical positioning of the top of the implant may not jeopardize the position of soft peri‐implant tissues, and that immediate restoration can be beneficial to minimize lateral bone loss. Further studies are suggested to evaluate the clinical significance of these results in longer healing periods.     

Plaque-induced inflammation around implants.

This article is a review of plaque-induced inflammation around dental implants. The microflora around successful implants is similar to healthy sulci, while that associated with failing implants is similar to periodontally diseased sites. Implant microflora is similar to the tooth microflora in the partially edentulous mouth. The microflora of implants in partially edentulous mouths differs from that in edentulous mouths. This seems to indicate a bacterial reservoir around the teeth and the possibility of reinfection of the implant sulcus by periodontal pathogens. The maintenance of a tooth microflora consistent with periodontal health in partially edentulous mouths may lead to maintaining an implant microflora consistent with peri-implant health. Thus, periodontal and implant maintenance are linked and neither can be overlooked.     

Hydroxylapatite-coated dental implants. Biologic rationale and surgical technique

Implant prosthodontics now offers our patients more benefits than conventional prosthetics. Considerations of bone biology, occlusal principles, occlusal materials, implant design, implant biomaterials, patient health profile, patient bone density and quality, site classification, manufacture quality and ethics, and operator efficiency all go into the prognosis and affect our final product. Emerging biomaterials help the clinician, in certain areas, to achieve a more predictable result. The time-tested principle--such as unloaded healing, atraumatic gentle surgical placement, and machined components--are carried along into the new systems that are being developed for clinical use. The use of the HA-coated cylinder has proved to be of extreme value in these past 5 years. It is another step closer to the ideal implant system.     

Effect of barrier membranes and autologous bone grafts on ridge width preservation around implants

Background: The purpose of this study was to explore the effect of barrier membranes and autologous bone grafts on the preservation of ridge width around implants. Materials and Methods: Sixty‐one patients were chosen from a database of case series; treatment assignment was based on clinical judgment. The patients received a total of 76 implants:34 implants with guided tissue regeneration procedures, 27 with autologous bone grafts, and 15 without ridge preservation procedures (control group). Results: The ridge width around the 76 implants decreased an average of 1.4 mm (95% CI, ‐1.9 to‐1.1 mm). Implants placed with autologous bone grafts or membranes tended to have worse outcomes. When compared to the no augmentation group, implants placed with guided tissue regeneration and autologous bone grafts resulted in 0.1 mm of additional bone loss (95% CI, ‐1.7 to ‐1.5 mm; p <.93) and 0.8 mm of additional bone loss (95% CI, ‐2.3 to 0.7 mm; p <.28), respectively. Conclusions: Autologous graft procedures or barrier membranes do not appear to improve crestal ridge preservation around implants.     

"Biologic width"and crestal bone remodeling with sintered porous-surfaced dental implants: a study in dogs

PURPOSE: The aim of this study was to obtain histometric measurements of bone and peri-implant mucosal tissue contact with implants of 2 sintered porous-surfaced designs. The "short-collar" design had a collar height (smooth coronal region) of 0.75 mm, while the "long-collar" model had a smooth coronal region of 1.8 mm. MATERIALS AND METHODS: Implants (2 per side) were placed in healed mandibular extraction sites of 4 beagle dogs using a submerged technique. After 4 weeks of healing, they were uncovered and used to support fixed partial dentures for a 9-month period. After sacrifice, specimens were retrieved and nondemineralized sections were examined histometrically to determine the most coronal bone-to-implant contact (first BIC) using the microgap as a reference and standard mucosal parameters of "biologic width." RESULTS: Significant (P = .001) differences in first BIC were found between designs (1.97 mm for long-collar versus 1.16 mm for short-collar implants) for posteriorly located implants but not for anteriorly located ones (1.21 mm versus 1.38 mm; P = .40). If crestal bone loss involved sintered surface, fibrous connective tissue ingrowth was observed to replace lost bone. No significant differences in peri-implant mucosal measurements (total peri-implant mucosal thickness; length of the epithelial component of this mucosa, and thickness of the connective tissue component) were detected between implant designs. CONCLUSIONS: Results suggest that "biologic width" accommodation drives initial crestal bone loss with sintered porous-surfaced implants. Histometric data obtained for bone contact showed no significant differences between the long- and short-collar implant designs.     

Microbiota around root-form endosseous implants: a review of the literature

Although high success rates for root-form endosseous implants have been reported, failures occasionally occur, and these implants must be removed. At least 10% of the failures have been suggested to be the result of peri-implantitis. There is some evidence that periodontal pathogens, mainly those belonging to the group of gram-negative anaerobic rods, play a role in the etiology of peri-implantitis. This article provides an overview of the literature associated with common peri-implant microbiology and an assessment as to whether bacteria associated with periodontitis exert a possible risk for peri-implant tissue breakdown. The peri-implant area is colonized by a large variety of oral microbial complexes. The microflora of the oral cavity prior to implant placement determines the composition of the microflora in the peri-implant area. Implants involved in peri-implantitis are colonized with large amounts of gram-negative anaerobic bacteria, including Fusobacteria, spirochetes, Bacteroides forsythus, and "black-pigmented bacteria" such as Prevotella intermedia, Prevotella nigrescens, and Porphyromonas gingivalis. Also, Actinobacillus actinomycetemcomitans can be isolated from these lesions. Thus, the microflora of peri-implantitis lesions resembles that of adult or refractory periodontitis. However, the presence of periodontal pathogens does not always lead to a destructive process. Therefore, the etiologic role of specific microorganisms in implant failure related to infection is still not resolved. Controversy remains as to whether organisms recovered from the original microflora cause the failure (and if so to what extent) or merely result from the infection. Nevertheless, there is accumulating evidence that bacteria cause the disease, while the individual's genetic makeup and environmental influences determine the severity of the disease.     

Assessing bone's adaptive capacity around dental implants: A literature review

BackgroundIncreased stress (force) on prostheses induces strain (deformation) in the peri-implant bone. Elevated stress and strain could result in the failure of implants that support prostheses. However, the survival rate of implants supporting prostheses under increased stress is high. Either the bone is stronger than expected or it adapts to increased stress. Concepts regarding bone’s adaptive capacity continue to evolve and are the focus of this literature review.Types of Studies ReviewedThe authors searched the literature to find studies that addressed the bone’s capacity to adjust to increased stress and strain. They assessed experimental and clinical trials in which investigators monitored healing after placement of dental implants.ResultsThe data indicate that forces greater than the bone’s adaptive ability can induce loss of osseointegration, as well as osseous resorption. In contrast, it is possible that increased stress on prostheses initiates a reparative process, thereby facilitating retention of implants experiencing increased stress. Numerous lines of evidence support the concept that bone can modify itself to withstand increased mechanical forces.Practical ImplicationsThe authors provide an explanation for the high success rate of prostheses and implants in bone that are exposed to increased stress and strain.     

Oral squamous cell carcinoma around dental implants.

It is well documented that oral squamous cell carcinoma (OSCC) is related to risk factors such as smoking and alcohol consumption as well as premalignant lesions and conditions such as leukoplakia, oral lichen planus (OLP), and previous malignancy of the upper respiratory system and gastrointestinal tract. Osseointegrated dental implants are rarely reported in association with OSCC. This article presents 2 cases of OSCC adjacent to dental implants in patients at risk for oral cancer--1 was a heavy smoker with OLP; the other had a history of previous oral and colon cancer. Six additional cases of malignancy adjacent to dental implants were retrieved from the literature; the majority of cases had at least 1 recognized risk factor for oral cancer. Although such cases are rarely reported, patients at risk for oral cancer, especially those with multiple existing risk factors, that present with failing dental implants should be thoroughly evaluated to rule out the presence of malignancy disguised as peri-implant disease.     

Maxillary and mandibular width changes studied using metallic implants.

The purpose of this implant study was to evaluate the transverse stability of the basal maxillary and mandibular structures. The sample included 25 subjects between 12 and 18 years of age who were followed for approximately 2.6 years. Metallic implants were placed bilaterally into the maxillary and mandibular corpora before treatment. Once implant stability had been confirmed, treatment (4 first premolar extractions followed by fixed appliance therapy) was initiated. Changes in the transverse maxillary and mandibular implants were evaluated cephalometrically and two groups (GROW+ and GROW++; selection based on growth changes in facial height and mandibular length) were compared. The GROW++ group showed significant width increases of the posterior maxillary implants (P <.001) and the mandibular implants (P =.009); there was no significant change for the anterior maxillary implants. The GROW+ group showed no significant width changes between the maxillary and mandibular implants. We conclude that (1) there are significant width increases during late adolescence of the basal mandibular and maxillary skeletal structures and (2) the width changes are related with growth potential.     

Early wound healing around endosseous implants: a review of the literature

The knowledge base of information related to early wound healing around endosseous dental implants is rapidly changing and expanding. Unless one is directly involved with creating this pool of information or has an extraordinary interest in the literature of the field, it is difficult to keep up to date with the flow of information. This article is intended to provide the clinician with a state-of-the-art review of the current literature related to early wound healing and the creation of an osseointegrated interface between living and nonliving structures. While some literature dealing with basic laboratory studies including tissue culture is discussed, the primary focus of the article is the in vivo literature, ie, animal and human studies.