Roberto Crespi

Role of primary stability for successful osseointegration of dental implants: Factors of influence and evaluation

A secure implant primary (mechanical) stability is positively associated with a successful implant integration and long-term successful clinical outcome. Therefore, it is essential to assess the initial stability at different time-points to ensure a successful osseointegration. The present study critically reviews the factors that may play a role in achieving a successful initial stability in dental implants. Databases were searched from 1983 up to and including October 2013 using different combinations of various keywords. Bone quality and quantity, implant geometry, and surgical technique adopted may significantly influence primary stability and overall success rate of dental implants.

Bacterial plaque colonization around dental implant surfaces

Purpose:To examine the distribution of bacteria into the internal and external surfaces of failed implants using histologic analysis. Materials and Methods:There were 10 failed pure titanium and 5 failed hydroxyapatite-coated titanium implants consecutively removed various years after their placement. Criteria for fixture removal were peri-implant radiolucency and clinical mobility. The mobile fixtures were retrieved with the patients under local anesthesia. Fixtures were removed maintaining the abutments with the aim to observe the bacterial infiltration at the level of abutment/implant interface and on the implant surface. Results:A thin radiolucent space was always present around all the failed implants. The abutments screws were tightly secured in all clinicalcases. The bacterial cells were composed of cocci and filaments, which were adherent to the implant surface with an orientation perpendicular to the long axis of the implant. All the specimens included in this study showed bacteria at the level of implant/abutment interface. Conclusions:Histologic analysis at the level of abutment/implant interface in 2-stage implants identified heavy bacterial colonization. These findings appear to support those studies showing bacteria penetration at the level of the micro-gap, which can legitimate the hypothesis that the micro-gap at the bone level could present a risk for bone loss caused by bacterial colonization.

Fresh-socket implants in periapical infected sites in humans.

BACKGROUND The aim of the present study is to compare the outcome of the immediate placement of implants when used in the replacement of teeth with and without chronic periapical lesions. METHODS Thirty patients requiring a single-tooth extraction of a monoradicular or premolar tooth were selected. The control group (CG) included 15 patients without periapical lesions but with root caries and root fractures. The test group (TG) included 15 patients with periapical lesions, periapical radiolucencies, and no signs of pain, fistulas, or suppuration. Thirty teeth were extracted, and implants were immediately positioned in fresh sockets and loaded after 3 months in both groups. Clinical parameters (probing depth [PD], modified plaque index, modified bleeding index [mBI], marginal gingiva level [MGL], and keratinized mucosa [KM]) and marginal bone levels were evaluated at baseline and 12 and 24 months after implant placement. Comparisons between CG and TG values over time were performed by the Student two-tailed t test. RESULTS At the 24-month follow-up, a survival rate of 100% was reported for all implants. The mean bone loss was 0.82 +/- 0.52 mm for the CG and 0.86 +/- 0.54 for the TG. Plaque accumulation was 0.74 +/- 0.29 for the CG and 0.69 +/- 0.29 for the TG. The mBI was 0.77 +/- 0.33 for the CG and 0.72 +/- 0.36 for the TG. The soft tissue profile MGL and KM remained stable for up to 24 months for the CG and TG. The mean PD was 2.05 +/- 0.66 mm for the CG and 1.99 +/- 0.57 mm for the TG. Differences that were not statistically significant were reported between the CG and TG over time and between time points. CONCLUSION At the 24-month follow-up, endosseous implants placed immediately in extraction sites affected by periapical infection rendered an equally favorable soft and hard tissue integration of the implants, revealing a predictable outcome.

Implant surface morphology and primary stability: is there a connection?

Purpose:The aim was to review the influence of surface morphology on the primary stability of dental implants. Methods:MEDLINE-PubMed databases were explored from 1991 up to and including April 2010 using different combinations of the following terms: “dental,” “implant surface roughness,” “immediate loading,” “initial stability,” “primary stability,” and “osseointegration.” Articles published only in English language were included and hand searching was also performed. Letters to the Editor and unpublished data were excluded. Results:Ten studies (three clinical and seven experimental) were included according to the search databases. In six studies (three experimental and three clinical), the implant stability was measured at least after 4 weeks after implant insertion; and primary implant stability was recorded in four experimental studies, using the insertion and removal torque tests and resonance frequency analysis using implant stability quotient values. Conclusion:Rough-surfaced implants have significantly higher success rates compared with dental implants with smooth surfaces; however, the question “Is there a connection between implant surface roughness (microdesign) and primary stability?” remains unanswered.

A 4-Year Evaluation of the Peri-Implant Parameters of Immediately Loaded Implants Placed in Fresh Extraction Sockets

BACKGROUND The present study considers the correlation between the meaning of keratinized mucosa (KM) and the long-term maintenance of endosseous root-form dental implants placed in fresh sockets and immediately loaded. METHODS Twenty-nine patients requiring extractions of ≥2 teeth in the maxilla and mandible were selected. One-hundred thirty-two maxillary and 32 mandibular teeth, in the incisor, canine, and premolar regions, were extracted. Implants were positioned in fresh sockets and immediately loaded. Based on the amounts of KM, implants were categorized as follows: KM ≥2 mm (group A) and KM <2 mm (group B). Clinical parameters (probing depth, modified plaque index, modified bleeding index, and gingival index) and marginal bone levels were followed at 4 years after implant placement. Comparisons between group A and B values were performed by the Student two-tailed t test. RESULTS At 4-year follow-up, a survival rate of 100% was reported for all implants. The mean values of group B were significantly higher (P <0.05) than group A for the following parameters: gingival index (group A, 0.67 ± 0.09; group B, 1.01 ± 0.11); modified plaque index (group A, 1.18 ± 0.09; group B, 1.71 ± 0.12); and modified bleeding index (group A, 0.35 ± 0.05; group B, 0.78 ± 0.05). Gingival recession was significantly elevated in group B. In both group A and group B, up to 60% of gingival recession occurred within the first 6 months. For mean bone loss values, statistically non-significant differences were reported between groups. CONCLUSIONS At 4-year follow-up, the results suggested that the presence of mid-buccal KM is not a critical factor in the maintenance of interproximal bone level around fresh socket implants immediately loaded. Conversely, less width of KM is significantly associated with more gingival inflammation, more plaque accumulation, and more gingival recession.

Laser wavelengths and oral implantology.

In modern implant dentistry there are several clinical indications for laser surgery. Different laser systems have a considerable spectrum of application in soft and hard peri-implant tissues. The literature was searched for clinical application of different laser wavelengths in peri-implant tissues: second-stage surgery of submerged implants, treatment of infrabony defects, removal of peri-implant hyperplastic overgrowths, and, possibly, the preparation of bone cavities for implant placement. This report describes the state-of-the-art application of different laser systems in modern implant dentistry for the treatment of peri-implant lesions and decontamination of implant surfaces. Our study evaluated in vitro examinations, clinical experience and long-term clinical studies. The exact selection of the appropriate laser system and wavelength was dependent on the scientific evaluation of recent literature and the level of changes in implant and tissue temperatures during laser application. The significant reduction in bacteria on the implant surface and the peri-implant tissues during irradiation and the cutting effects associated with the coagulation properties of the lasers are the main reasons for laser application in the treatment of peri-implant lesions and the successful long-term prognosis of failing oral implants. The various applications of lasers in implant dentistry are dependent on the wavelength and laser–tissue interactions.

Immediate Loading of Dental Implants Placed in Periodontally Infected and Non-Infected Sites: A 4-Year Follow-Up Clinical Study

BACKGROUND The aim of the present study is to compare the outcomes of immediate loading of implants in replacing teeth with and without chronic periodontal lesions at 4 years of follow-up. METHODS Thirty-seven patients were included in this study. A total of 275 implants were placed and immediately loaded in extraction sockets, 197 in periodontally infected sites (infected sites group [IG]), and 78 implants in non-infected sites (non-infected sites group [NG]). Marginal bone levels and clinical parameters (plaque accumulation and bleeding index) were evaluated at baseline and 12, 24, and 48 months after implant placement. Comparisons between IG and NG values over time were performed by the Student two-tailed t test. RESULTS At 48 months of follow-up, the IG presented a survival rate of 98.9% because two implants were lost 1 month after placement; the NG reported a survival rate of 100%. The marginal bone level was 0.79 +/- 0.38 mm for the IG and 0.78 +/- 0.38 mm for the NG, plaque accumulation was 0.72 +/- 0.41 for the IG and 0.71 +/- 0.38 for the NG, and the bleeding index was 0.78 +/- 0.23 for the IG and 0.75 +/- 0.39 for the NG. No statistically significant differences were reported between the IG and NG over time and between time points. CONCLUSION At 48 months of follow-up, dental implants that were placed and immediately loaded in periodontally infected sockets showed no significant differences compared to implants placed in uninfected sites.

Periodontal tissue regeneration in beagle dogs after laser therapy.

Class III periodontal furcations still represent a challenge for the periodontist. Aim of this study was to test the effect of CO2 laser on the treatment of class III furcation defects.

Magnesium-Enriched Hydroxyapatite Versus Autologous Bone in Maxillary Sinus Grafting: Combining Histomorphometry With Osteoblast Gene Expression Profiles Ex Vivo

BACKGROUND Many biomaterials are proposed for sinus floor lifting and grafting in the posterior maxilla for insufficient bone volume (BV). The aim of this study was to compare the use of magnesium-enriched hydroxyapatite (mHA) versus autogenous bone graft (AB) for maxillary sinus lift procedures by histomorphometric and ex vivo gene expression profiling. METHODS Fifteen patients requiring bilateral maxillary sinus augmentation received autologous bone particles (group A) and mHA (group B) (split-mouth design). Five months later, implants were placed, and biopsies were obtained. Bone specimens were analyzed by histomorphometry, BV and vital bone (VB) percentages were calculated, and ex vivo osteoblast expansion followed by highly sensitive osteoblast specific gene expression profiling for cbfa1, osteocalcin, osteopontin, collagen type I, receptor activator of nuclear factor-kappa B ligand (RANKL), and osteoprotegerin (OPG) by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) were performed. Comparisons were made using the Student t test. RESULTS After healing with no complications, BV was comparable in the two groups (80.79% +/- 14.27% for autologous versus 76.72% +/- 11.47% for mHA; P = not statistically significant), but VB was lower in the mHA group (29.65% +/- 9.81% versus 78.40% +/- 16.72%; P <0.05). Real-time RT-PCR analyses showed significantly higher expression of the osteoblast differentiation factor Cbfa1 and the matrix formation marker osteocalcin in the mHA group compared to the AB group, whereas type I collagen was comparable, and osteopontin was decreased. Attesting to a lower osteoclastogenic potential, the RANKL/OPG ratio was diminished. CONCLUSIONS Autogenous bone samples provided higher vital over comparable total bone levels than mHA-grafted sites. Osteoblast gene expression profiles from mHA grafts revealed higher expression of certain specific markers of osteoblast differentiation and bone formation, associated with a lower osteoclastogenic potential.

Osteotome Sinus Floor Elevation and Simultaneous Implant Placement in Grafted Biomaterial Sockets: 3 Years of Follow-Up

BACKGROUND Immediate bone grafting procedures were proposed to preserve bone volume in residual damaged alveolar walls and to prevent the expansion of the sinus floor in the maxillary molar region. The use of an osteotome allows vertical bone augmentation and localized sinus elevation with minimal surgical trauma. The aim of this study is to evaluate the clinical outcome of implants placed in previously grafted alveoli that were expanded at a second-stage surgery by an osteotome technique. METHODS Twenty patients requiring extraction of one or two upper molar teeth and/or a second premolar were selected. Thirty teeth were extracted, and their fresh sockets immediately received magnesium-enriched hydroxyapatite as a graft material. Three months after bone filling, osteotome sinus floor elevations were performed in grafted sites, and 30 titanium dental implants were placed. Three months after implant placement, temporary restorations were performed. Follow-up examinations and intraoral digital radiographs were taken at baseline and 6, 12, 24, and 36 months after implant placement to evaluate the alveolar bone gain for each implant. Comparisons among mean values of alveolar bone gain over time were performed by the Student two-tailed t test. RESULTS At the 36-month follow-up, a survival rate of 100% was reported for all implants. The alveolar bone gain after 6 months of healing was 2.41 +/- 1.23 mm. Successively, after 12 months, the bone gain increased (3.85 +/- 1.37 mm). At 24 and 36 months after implant placement, the levels were stable (3.86 +/- 1.50 mm and 3.82 +/- 1.57 mm, respectively). Statistical analyses showed a significant difference (P <0.05) only between the 6- and 12-month values. CONCLUSION At the 36-month follow-up, the use of the osteotome technique for vertical expansion of the grafted tissue was considered a predictable procedure in the implant surgery.