Dimensional Accuracy of Computer-Aided Design/Computer-Assisted Manufactured Orbital Prostheses

Purpose: The aim of this research was to assess the dimensional accuracy of orbital prostheses based on reversed images generated by computer-aided design/computer-assisted manufacturing (CAD/CAM) using computed tomography (CT) scans. Materials and Methods: CT scans of the faces of 15 adults, men and women older than 25 years of age not bearing any congenital or acquired craniofacial defects, were processed using CAD software to produce 30 reversed three-dimensional models of the orbital region. These models were then processed using the CAM system by means of selective laser sintering to generate surface prototypes of the volunteers` orbital regions. Two moulage impressions of the faces of each volunteer were taken to manufacture 15 pairs of casts. Orbital defects were created on the right or left side of each cast. The surface prototypes were adapted to the casts and then flasked to fabricate silicone prostheses. The establishment of anthropometric landmarks on the orbital region and facial midline allowed for the data collection of 31 linear measurements, used to assess the dimensional accuracy of the orbital prostheses and their location on the face. Results: The comparative analyses of the linear measurements taken from the orbital prostheses and the opposite sides that originated the surface prototypes demonstrated that the orbital prostheses presented similar vertical, transversal, and oblique dimensions, as well as similar depth. There was no transverse or oblique displacement of the prostheses. Conclusion: From a clinical perspective, the small differences observed after analyzing all 31 linear measurements did not indicate facial asymmetry. The dimensional accuracy of the orbital prostheses suggested that the CAD/CAM system assessed herein may be applicable for clinical purposes. Int J Prosthodont 2010;23:271-276.

The Importance of Adhesive Area Delimitation in a Microshear Bond Strength Experimental Design

Purpose: The purpose of this study was to assess the influence of adhesive area delimitation on the microshear bond strength of different adhesives to dentin. Materials and Methods: Eighteen bovine incisors were sectioned and the exposed dentin surfaces were prepared with 600-grit SIC paper. These teeth were randomly divided into three groups, according to the adhesive to be applied: two-step etch-and-rinse Adper Single Bond 2 (3M ESPE), two-step self-etching Clearfil SE Bond (Kuraray), and one-step Clearfil S(3) Bond (Kuraray). On each dentin surface, 4 samples were built up with the composite resin Z100 (3M ESPE); on 2 of these, a suggested area delimitation technique was employed. After 24 h of storage in water at 37 degrees C, samples were subjected to the microshear bond strength test, and the failure modes were evaluated under optical and scanning electron microscopes. The obtained results were statistical analyzed using two-way ANOVA and Tukey`s test. Results: Groups without area delimitation presented significantly higher bond strength results (p < 0.05) and a higher incidence of cohesive failures. In these groups, fractures tended to occur beyond the limits of the actual adhesive area, while the area restriction technique succeeded in avoiding this phenomenon. The three adhesives performed similarly when area delimitation was employed (p > 0.05), but Clearfil S(3) Bond showed significantly higher bond strength results when no area delimitation was taken into account (p < 0.05). Conclusion: The extension of the adhesive area beyond the limits of the composite cylinder may play an important role in the results of microshear bond strength tests, while the suggested area delimitation technique may lead to less questionable outcomes.

The success of endosseous implants in human immunodeficiency virus-positive patients receiving antiretroviral therapy A pilot study

Background. In a pilot study, the authors aimed to determine the success rate of dental implants placed in patients who were positive for human immunodeficiency virus (HIV) and were receiving different regimens of highly active anti-retroviral therapy (HAART). They considered patients` levels of cluster of differentiation (CD) 4(+) cells and viral load, and they attempted to verify whether patients with baseline biochemical signs of bone mineral density loss could experience osseointegration impairment. Materials and Methods. One of the authors, a dentist, placed dental implants in the posterior mandibles of 40 volunteers, divided into three groups: one composed of HIV-positive patients receiving protease inhibitor (PI)-based HAART; a second composed of HIV-positive patients receiving nonnucleoside reverse transcriptase inhibitor based HAART (without PI); and a control group composed of HIV-negative participants. The authors assessed pen-implant health six and 12 months after implant loading. They analyzed the success of the implants in relation to CD4(+) cell counts, viral load and baseline pyridinoline and deoxypyridinoline values. Results. The authors followed 59 implants for 12 months after loading. Higher baseline levels of pyridinoline and deoxypyridinoline found in HIV-positive participants did not interfere with osseointegration after 12 months of follow-up. Average pen-implant bone loss after 12 months was 0.49 millimeters in group 1, 0.47 mm in group 2, and 0.55 mm in the control group. Conclusions. The placement of dental implants in HIV-positive patients is a reasonable treatment option, regardless of CD4(+) cell count, viral load levels and type of antiretroviral therapy. Longer, follow-up periods are necessary to ascertain the predictability of the long-term success of dental implants in these patients. Clinical Implications. Limited published scientific evidence is available to guide clinicians in regard to possible increased risks associated with dental implant placement in HIV-positive patients.

Assessment of the Availability of Bone Volume for Grafting in the Donor Retromolar Region Using Computed Tomography: A Pilot Study

Purpose: The purpose of this study was to evaluate the area and volume of bone available for grafting in a donor retromolar region using computed tomography (CT). Materials and Methods: Ten patients previously scanned by multislice CT were selected for evaluation. Images from partially and completely dentate patients at least 18 years of age were included in the study; those from patients with impacted or erupted third molars or intrabony lesions in the study area were not included. Computer software with appropriate tools was used to handle the images. Two calibrated observers made measurements separately. Safety margins in relation to the lingual cortex, the base of mandible, and the alveolar canal were established in each cross-section of the CTs. Measurements were done by using cross-sectional views, and the results were calculated after three-dimensional reconstruction, providing area and volume data. Results: The mean area of bone available for grafting was 8.12 cm(2) ( range, 0.00 to 13.60 cm(2)) and 8.32 cm(2) ( range, 0.00 to 14.30 cm(2)) for observers 1 and 2, respectively. Mean available bone volume for grafting was 0.79 cm(3) ( range, 0.00 to 1.50 cm(3)) for observer 1 and 0.85 cm(3) ( range, 0.00 to 1.60 cm(3)) for observer 2. Interobserver analysis showed substantial agreement. Conclusion: The retromolar region showed a wide variety of anatomic differences among patients. Three-dimensional multislice CT allows reproducible measurements of the area and volume of the retromolar region. Int J Oral Maxillofac Implants 2010; 25: 374-378

Treatment of infrabony defects with or without enamel matrix proteins: A 24-month follow-up randomized pilot study

Objective: To evaluate a comparison of open-flap debridement (OFD) with or without the use of enamel matrix proteins (EMP) for the treatment of infrabony defects. Method and Materials: Ten volunteers (38 infrabony defects) were randomized to receive OFD + EMP (test site) and OFD (control site). Clinical outcomes included mean changes in Plaque Index, Gingival Index, probing pocket depth (PPD), relative attachment level (RAL), gingival recession, width of keratinized tissue, and dental mobility at baseline and at 24 months. Results: A significant reduction of 4.21 +/- 0.97 mm was observed in PPD for the OFD + EMP group (from 6.30 +/- 0.99 mm to 2.09 +/- 0.97 mm) and of 3.28 +/- 1.23 mm for the OFD group (from 6.13 +/- 0.88 mm to 2.85 +/- 1.42 mm) (P < .001). The reduction in PPD was statistically significantly greater for OFD + EMP compared to OFD (P = .03). The mean RAL decreased from 13.26 +/- 1.88 mm to 7.57 +/- 2.05 mm for the OFD + EMP group (a gain of 5.69 +/- 1.96 mm) and from 13.37 +/- 1.71 mm to 8.13 +/- 1.34 min (P < .001) for the OFD group (a gain of 5.24 +/- 1.55 mm). Gingival recession was higher it) the OFD + EMP group than in the OFD group. The mean keratinized tissue significantly decreased from 4.41 +/- 1.39 mm to 3.63 +/- 1.54 mm for OFD flap group (P < .01). Conclusion: Both treatment modalities were efficient in improving RAL and PPD. Within groups, there was a significant reduction in keratinized tissue for OFD and a significant postoperative recession for the OFD + EMP group. Infrabony defects treated with OFD + EMP showed significantly more PPD reduction when compared to OFD. (Quintessence Int 2010;41:125-134)

Precise Insertion of Orthodontic Miniscrews with a Stereolithographic Surgical Guide Based on Cone Beam Computed Tomography Data: A Pilot Study

Purpose: Orthodontic miniscrews are commonly used to achieve absolute anchorage during tooth movement. One of the most frequent complications is screw loss as a result of root contact. Increased precision during the process of miniscrew insertion would help prevent screw loss and potential root damage, improving treatment outcomes. Stereo lithographic surgical guides have been commonly used for prosthetic implants to increase the precision of insertion. The objective of this paper was to describe the use of a stereolithographic surgical guide suitable for one-component orthodontic miniscrews based on cone beam computed tomography (CBCT) data and to evaluate implant placement accuracy. Materials and Methods: Acrylic splints were adapted to the dental arches of four patients, and six radiopaque reference points were filled with gutta-percha. The patients were submitted to CBCT while they wore the occlusal splint. Another series of images was captured with the splint alone. After superimposition and segmentation, miniscrew insertion was simulated using planning software that allowed the user to check the implant position in all planes and in three dimensions. In a rapid-prototyping machine, a stereolithographic guide was fabricated with metallic sleeves located at the insertion points to allow for three-dimensional control of the pilot bur. The surgical guide was worn during surgery. After implant insertion, each patient was submitted to CBCT a second time to verify the implant position and the accuracy of the placement of the miniscrews. Results: The average differences between the planned and inserted positions for the ten miniscrews were 0.86 mm at the coronal end, 0.71 mm at the center, and 0.87 mm at the apical tip. The average angular discrepancy was 1.76 degrees. Conclusions: The use of stereolithographic surgical guides based on CBCT data allows for accurate orthodontic mini screw insertion without damaging neighboring anatomic structures. INT J ORAL MAXILLOFAC IMPLANTS 2011;26:860-865

Clinical, Histological, and Microbiological Findings in Peri-Implant Disease: A Pilot Study

Objectives: This study is intended to verify the correlation among clinical indices of the peri-implant soft tissues, the histological condition and the presence of 3 pathogens commonly associated with peri-implant diseases (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Tannerella forsythia). Materials: Four clinical indices, Gingival Index (GI), Sulcus Bleeding Index, GI modified by Mombelli, and Plaque Index modified by Mombelli (mPI) were evaluated around I dental implant of each subject (n = 10). Subgingival plaque was collected for bacterial analysis (polymerase chain reaction) and a biopsy of peri-implant soft tissues for histological analysis was harvested. The clinical indices and detected pathogens correlated with a developed histological index (HI). Results: There was no statistically significant relationship between the clinical indices (GI, Sulcus Bleeding Index, and GI modified by Mombelli) and the HI, except for the mPI on the central area of lingual aspects (r = 0.85, P = 0.0029). There was a tendency for a positive correlation between the mPI on the central area of buccal aspects and the HI (r = 0.63, P = 0.0544). The counting of lymphocytes and plasmocytes correlated positively with 111, thus suggesting the index reliability. The prevalence of A. actinomycetemcomitans, P. gingivalis, and T. forsythia did not present a significant relationship with the HI. Conclusion: Despite the small number of samples and the poor statistical significance, the mPI seems to be useful for evaluation of inflammatory severity on soft tissue around dental implants as demonstrated by its relationship with the HI. Further studies are necessary to elucidate this subject. (Implant Dent 2009;18:334-344)