Influence of lateral pressure to the implant bed on osseointegration: an experimental study in dogs

AimTo study osseointegration and bone-level changes at implants installed using either a standard or a reduced diameter bur for implant bed preparation.Material and methodsIn six Labrador dogs, the first and second premolars were extracted bilaterally. Subsequently, mesial roots of the first molars were endodontically treated and distal roots, including the corresponding part of the crown, were extracted. After 3 months of healing, flaps were elevated and recipient sites were prepared in all experimental sites. The control site was prepared using a standard procedure, while the test site was prepared using a drill with a 0.2 mm reduced diameter than the standard one used in the contra-lateral side. After 4 months of healing, the animals were euthanized and biopsies were obtained for histological processing and evaluation.ResultsWith the exception of one implant that was lost, all implants were integrated in mineralized bone. The alveolar crest underwent resorption at control as well as at test sites (buccal aspect similar to 1 mm). The most coronal contact of bone-to-implant was located between 1.2 and 1.6 mm at the test and between 1.3 and 1.7 mm at the control sites. Bone-to-implant contact percentage was between 49% and 67%. No statistically significant differences were found for any of the outcome variables.ConclusionsAfter 4 months of healing, lateral pressure to the implant bed as reflected by higher insertion torques (36 vs. 15 N cm in the premolar and 19 vs. 7 N cm in the molar regions) did not affect the bone-to-implant contact.To cite this article:Pantani F, Botticelli D, Garcia IR Jr., Salata LA, Borges GJ, Lang NP. Influence of lateral pressure to the implant bed on osseointegration: an experimental study in dogs.Clin. Oral Impl. Res. 21, 2010; 1264-1270.doi: 10.1111/j.1600-0501.2009.01941.x.

Patients' Expectations of and Satisfaction with Implant-Supported Fixed Partial Dentures and Single Crowns

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Patients' Expectations Before and Evaluation After Dental Implant Therapy

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Evaluation of Different Methods of Optical Impression Making on the Marginal Gap of Onlays Created with CEREC 3D

Objectives: This study evaluated the marginal gaps on several surfaces of onlays created with the Cerec 3D system using one intraoral and two extraoral optical impression methods. Methods: A human molar (#19) was mounted with its adjacent teeth on a typodont (Frasaco) and prepared for a MODL onlay. The typodont was assembled in the mannequin head in order to simulate clinical conditions. The same operator took 36 individual optical impressions using a CEREC 3D camera. For group 1 (IP), a thin layer of titanium dioxide powder (CEREC powder-VITA) was applied directly onto the surface of the preparation for imaging (n=12). For group 2 (EP), a sectional impression was taken with hydrocolloid Identic Syringable (Dux Dental), a die made with polyvinylsiloxane KwikkModel Scan (R-dental Dentalerzeugnisse GmbH) and powdered with titanium dioxide for imaging (n=12). For group 3 (ES), a sectional impression was taken with PVS and a sectional stock tray, a die fabricated in stone (Diamond die- HI-TEC Dental Products) and the die being imaged without powdering (n=12). One operator designed and machined the onlays in Vita Blocks Mark II for Cerec (VITA) using a CEREC 3D. The marginal gaps (pm) were measured with an optical microscope (50x) at 12 points, three on each surface of the MODL. The results were analyzed by two-way ANOVA/Tukey's (p=0.05). Results: The overall mean marginal gaps (mu m) for the three methods were: IP=111.6 (+/- 34.0); EP=161.4 (+/- 37.6) and ES=116.8 (+/- 42.3). IP and ES were equal, but both were significantly less than EP. The pooled mean marginal gaps (mu m) for the occlusal = 110.5 (+/- 39) and lingual = 111.5 (+/- 30.5) surfaces were equivalent and significantly less than the distal = 136.5 (+/- 42.5) and mesial = 161.1 (+/- 43.3). Conclusion: The marginal gap of CEREC 3D onlay restorations was not different when the optical impression was taken intraorally vs extraorally using a stone cast that does not require powdering. The lingual and occlusal surfaces showed the lowest gaps.

Influence of various implant platform configurations on peri-implant tissue dimensions: an experimental study in dog

AimTo evaluate the influence (i) of various implant platform configurations and (ii) of implant surface characteristics on peri-implant tissue dimensions in a dog model.Material and methodsMandibular premolars and first molars were extracted bilaterally in six Labrador dogs. After 3 months of healing, two implants, one with a turned and a second with a moderately rough surface, were installed on each side of the mandible in the premolar region. on the right side of the mandible, implants with a tapered and enlarged platform were used, while standard cylindrical implants were installed in the left side of the mandible. Abutments with the diameter of the cylindrical implants were used resulting in a mismatch of 0.25 mm at the tapered implant sites. The flaps were sutured to allow a non-submerged healing. After 4 months, the animals were sacrificed and ground sections were obtained for histometric assessment.ResultsAll implants were completely osseointegrated. A minimal buccal bone resorption was observed for both implant configurations and surface topographies. Considering the animals as the statistical unit, no significant differences were found at the buccal aspect in relation to bone levels and soft tissue dimensions. The surface topographies did not influence the outcomes either.ConclusionsThe present study failed to show differences in peri-implant tissue dimensions when a mismatch of 0.25 mm from a tapered platform to an abutment was applied. The surface topographies influence a neither marginal bone resorption or peri-implant soft tissue dimension.To cite this article:Baffone GM, Botticelli D, Pantani F, Cardoso LC, Schweikert MT, Lang NP. Influence of various implant platform configurations on peri-implant tissue dimensions: an experimental study in dog.Clin. Oral Impl. Res. 22, 2011; 438-444.

Group A T-loop for differential moment mechanics: An implant study

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of disinfectant agents on dimensional stability of elastomeric impression materials.

STATEMENT OF PROBLEM: Difficulties in sterilizing impressions by traditional methods have led to chemical disinfection as an alternative, and some studies have shown that disinfectants may adversely affect impressions. PURPOSE: This study investigated the effect of disinfection methods on the dimensional stability of 6 elastomeric materials. MATERIAL AND METHODS: Impression materials were submitted to the following treatments: immersion in 5.25% sodium hypochlorite solution for 10 minutes, immersion in 2% glutaraldehyde solution for 30 minutes, and no immersion (control). After treatments, impressions were poured, and respective stone casts were measured with a Nikon Profile projector and compared with the master model. RESULTS: The elastomeric materials had different reproduction capacities, and the disinfecting treatments did not differ from the control.

Homogenous implant in rat tibias of matrix preserved in 98% glycerin: histomorphologic study.

As a chemical medium for preservation of tissues, glycerin has shown good results because it maintains the cellular integrity despite the tissue dehydration it causes. Taking advantage of the osteoinducing properties of the osseous matrix and glycerin as a proper medium for tissue preservation, osseous matrix was implanted in rat tibias. Twenty-four rats were used, each receiving two surgical wounds. In one of the wounds an osseous matrix preserved in 98% glycerin was implanted and the other received a matrix without preservatives. Six animals were sacrificed on days 10, 20, 30 and 60 post-implant. After routine histological processing, the specimens were stained in hematoxylin-eosin and Masson's trichrome. The results showed that the matrixes preserved in glycerin presented faster resorption with replacement by newly formed tissue.

Microbiologic and radiographic analysis of ligature-induced peri-implantitis with different dental implant surfaces

Purpose: The goal of this study was to evaluate microbiota and radiographic peri-implant bone loss associated with ligature-induced peri-implantitis. Materials and Methods: Thirty-six dental implants with 4 different surfaces (9 commercially pure titanium, 9 titanium plasma-sprayed, 9 hydroxyapatite, and 9 acid-etched) were placed in the edentulous mandibles of 6 dogs. After 3 months with optimal plaque control, abutment connection was performed. On days 0, 20, 40, and 60 after placement of cotton ligatures, both microbiologic samples and periapical radiographs were obtained. The presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia/nigrescens, Campylobacter spp, Capnocytophaga spp, Fusobacterium spp, beta-hemolytic Streptococcus, and Candida spp were evaluated culturally. Results: P intermedia/nigrescens was detected in 13.89% of implants at baseline and 100% of implants at other periods. P gingivalis was not detected at baseline, but after 20 and 40 days it was detected in 33.34% of implants and at 60 days it was detected in 29.03% of dental implants. Fusobacterium spp was detected in all periods. Streptococci were detected in 16.67% of implants at baseline and in 83.34%, 72.22%, and 77.42% of implants at 20, 40, and 60 days, respectively. Campylobacter spp and Candida spp were detected in low proportions. The total viable count analysis showed no significant differences among surfaces (P = .831), although a significant difference was observed after ligature placement (P < .0014). However, there was no significant qualitative difference, in spite of the difference among the periods. The peri-implant bone loss was not significantly different between all the dental implant surfaces (P = .908). Discussion and Conclusions: These data suggest that with ligature-induced peri-implantitis, both time and periodontal pathogens affect all surfaces equally after 60 days.

Experimental peri-implant tissue breakdown around different dental implant surfaces: Clinical and radiographic evaluation in dogs

Purpose: Tissue reactions to 4 different implant surfaces were evaluated in regard to the development and progression of ligature-induced peri-implantitis. Materials and Methods: In 6 male mongrel dogs, a total of 36 dental implants with different surfaces (9 titanium plasma-sprayed, 9 hydroxyapatite-coated, 9 acid-etched, and 9 commercially pure titanium) were placed 3 months after mandibular premolar extraction. After 3 months with optimal plaque control, abutment connection was performed. Forty-five days later, cotton ligatures were placed around the implants to induce peri-implantitis. At baseline and 20, 40, and 60 days after placement, the presence of plaque, peri-implant mucosal redness, bleeding on probing, probing depth, clinical attachment loss, mobility, vertical bone loss, and horizontal bone loss were assessed. Results: The results did not show significant differences among the surfaces for any parameter during the study (P > .05). All surfaces were equally susceptible to ligature-induced peri-implantitis over time (P < .001). Correlation analysis revealed a statistically significant relationship between width of keratinized tissue and vertical bone loss (r 2 = 0.81; P = .014) and between mobility and vertical bone loss (r 2 = 0.66; P = .04), both for the titanium plasma-sprayed surface. Discussion and Conclusions: The present data suggest that all surfaces were equally susceptible to experimental peri-implantitis after a 60-day period.

Evaluation of transfer impressions for osseointegrated implants at various angulations

The accuracy of impressions that transfer the relationship of the implant to the metal framework of the prosthesis continues to be a problem. This study was designed to evaluate the accuracy of the transfer process under variable conditions with regard to implant analog angulations, impression materials, and techniques. Replicas (n = 60) of a metal matrix (control) containing four implants at 90°, 80°, 75°, and 65° in relation to the horizontal surface were obtained by using three impression techniques: T1 - indirect technique with conical copings in closed trays; T2 - direct technique with square copings in open trays; and T3 - square copings splinted with autopolymerizing acrylic resin; and four elastomers: P-polysulfide; I-polyether; A-addition silicone; and Z-condensation silicone. The values of the implant analog annulations were assessed by a profilometer to the nearest 0.017°, then submitted to analysis of variance for comparisons at significance of 5% (P < .05). For implant analog at 90°, the material A associated with T2 and material Z with T3 behaved differently (P < .05) from all groups. At 80°, all materials behaved differently (P < .01) with T1. At 75°, when T1 was associated, materials P and A showed similar behavior, as well as materials I and Z; however, P and A were different from I and Z (P < .01). When T3 was associated, all experimental groups behaved differently among them (P < .01). At 65°, the materials P and Z behaved differently (P < .01) from the control group with T1, T2, and T3; the materials I and A behaved differently from the control group (P < .01) when T1 and T2, respectively, were associated. The more perpendicular the implant analog annulation is in relation to the horizontal surface, the more accurate the impression. The best materials were material I and A and the most satisfactory technique was technique 3.

The effect of CO 2 laser irradiation on failed implant surfaces

The aim of this investigation was to evaluate the cleaning effect of CO 2 on surface topography and composition of failed dental implant surfaces. Ten failed dental implants were retrieved from nine patients (mean age, 46.33 ± 5.81 years) as a result of early or late failure. The implants were divided into two parts: one side of the implant was irradiated with a CO 2 laser (test side), while the other side did not receive irradiation (control side). The CO 2 laser was operated at 1.2 W in a continuous wave for 40 seconds (40 J energy). The handpiece of the CO 2 laser was kept at a distance of 30 mm from the implant surface, resulting in a spot area of 0.031415 cm 2 (38.20 W/cm 2; 1559 J/cm 2) in scanning mode (cervical-apical). One unused dental implant was used as a negative control for both groups. All implant surfaces were examined by scanning electron mi croscopy (SEM) and energy-dispersive spectrometer x-ray (EDS) for element analysis. SEM showed that the surface of the test sides consisted of different degrees of organic residues, appearing mainly as dark stains similar to those observed on the control sides. None of the test surfaces presented alterations such as crater-like alterations, lava-like layers, or melting compared with the nonirradiated surfaces. Foreign elements such as carbon, oxygen, sodium, calcium, and aluminum were detected on both sides. These results suggest that CO 2 laser irradiation does not modify the implant surface, although the cleaning effect was not satisfactory.

Powder processing and In Vivo evaluation of a titanium porous coating implant

The processing of titanium porous coatings using powder metallurgy technique to achieve a porous structure that allows osseointegration with bone tissue was discussed. The porous microstructure exhibited micropores and interconnected macropores with size ranges that allowed bone ingrowth. The macropores in the coatings were originated from the binder evaporation while the micropore was related with the porous titanium powder and the low compaction pressure used. The in vivo evaluation indicated that osseointegration had occurred between the bone and porous material.

Zygomatic bone: Anatomic bases for osseointegrated implant anchorage

Purpose: The aim of the present study was to evaluate zygomatic bone thickness considering a possible relationship between this parameter and cephalic index (Cl) for better use of Cl in the implant placement technique. Materials and Methods: Cl was calculated for 60 dry Brazilian skulls. The zygo matic bones of the skulls were divided into 13 standardized sections for measurement. Bilateral measurements of zygomatic bone thickness were made on dry skulls. Results: Sections 5, 6, 8, and 9 were appropriate for implant anchorage in terms of location. The mean thicknesses of these sections were 6.05 mm for section 5, 3.15 mm for section 6, 6.13 mm for section 8, and 4.75 mm for section 9. In only 1 section, section 8, did mean thickness on 1 side of of the skull differ significantly from mean thickness on the other side (P <.001). Discussion: For the relationship between quadrant thick ness and Cl, sections 6 and 8 varied independently of Cl. Section 5 associated with brachycephaly, and section 9 associated with subbrachycephaly, presented variations in the corresponding thickness. Conclusion: Based on the results, implants should be placed in sections 5 and 8, since they presented the greatest thickness, except in brachycephalic subjects, where thickness was greatest in section 5, and in subbrachycephalic subjects, where thickness was greatest in section 9. Cl did not prove to be an appropriate parameter for evaluating zygomatic bone thickness for this sampling.

Histomorphometric evaluation of a threaded, sandblasted, acid-etched implant retrieved from a human lower jaw: A case report

The purpose of this study was to histomorphometrically evaluate the bone-to-implant contact and bone area around a titanium implant retrieved from a human lower jaw. A screw-shaped titanium implant (sandblasted and acid-etched surface) was removed from a 68-year-old male after having been in function for 40 months because of a fracture of the abutment screw. Following the implant removal, an undecalcified section was obtained. The histomorphometric analysis showed a rate of 75.40% of bone-to-implant contact and 89.30% of bone area filling within the limits of the implant threads. The surrounding bone healed in a well-organized pattern and could not be differentiated from the anginal alveolus. The histologic evidence showed a high degree of osseointegration in a threaded, sandblasted, and acid-etched implant retrieved from a human lower jaw after functional loading for 40 months. Copyright © 2005 by Lippincott Williams & Wilkins.