Luigi Vito Stefanelli

Platelet Rich Fibrin (P.R.F.) in reconstructive surgery of atrophied maxillary bones: clinical and histological evaluations.

Introduction. Maxillary bone losses often require additional regenerative procedures: as a supplement to the procedures of tissue regeneration, a platelet concentrate called PRF (Platelet Rich Fibrin) was tested for the first time in France by Dr. Choukroun. Aim of the present study is to investigate, clinically and histologically, the potential use of PRF, associated with deproteinized bovine bone (Bio-Oss), as grafting materials in pre-implantology sinus grafting of severe maxillary atrophy, in comparison with a control group, in which only deproteinized bovine bone (Bio-Oss) was used as reconstructive material. Materials and Methods. 60 patients were recruited using the cluster-sampling method; inclusion criteria were maxillary atrophy with residual ridge < 5mm. The major atrophies in selected patients involved sinus-lift, with a second-look reopening for the implant insertion phase. The used grafting materials were: a) Bio-Oss and b) amorphous and membranous PRF together with Bio-Oss. We performed all operations by means of piezosurgery in order to reduce trauma and to optimize the design of the operculum on the cortical bone. The reopening of the surgical area was scheduled at 3 different times. Results. 72 sinus lifts were performed with subsequent implants insertions. We want to underline how the histological results proved that the samples collected after 106 days (Early protocol) with the adding of PRF were constituted by lamellar bone tissue with an interposed stroma that appeared relaxed and richly vascularized. Conclusions. The use of PRF and piezosurgery reduced the healing time, compared to the 150 days described in literature, favoring optimal bone regeneration. At 106 days, it is already possible to achieve good primary stability of endosseous implants, though lacking of functional loading.

How accurate is CBCT in measuring bone density? A comparative CBCT-CT in vitro study.

PURPOSE Recently, cone beam computed tomography (CBCT) has become widely used for oral and maxillofacial imaging. Twenty dry mandibles were CBCT and conventional multislice CT scanned to evaluate if there is a statistically significant difference between the bone density values they produce, defined as gray density values, and to determine any correlation between them. MATERIALS AND METHODS Using software and a radiographic template, the CT and CBCT scan images were overlapped, and two data sets were created, each one giving the respective gray values (voxel value [VV] or Hounsfield unit [HU]) of the same area with the same spatial coordinates. For the statistical analysis, t-test, Pearsons correlation, and Pearsons r were used. RESULTS The differences between the CBCT (VV) and CT (HU) gray density values were statistically significant (p ≤ .05), whereas the Pearsons correlation coefficients and Pearsons r-values demonstrated a statistically significant linear correlation between VV and HU gray density values. CONCLUSION The lower radiation dose and reduced costs of CBCT make this a useful substitute for CT; however, this study has shown that, in order to more accurately define the bone density with CBCT, a conversion ratio needs to be applied to the VV.

Depth deviation and occurrence of early surgical complications or unexpected events using a single stereolithographic surgi-guide §

The purpose of this study was to determine the accuracy of depth implant insertion and to describe the frequency of early surgical complications or unexpected events, recorded using a single, totally guided, stereolithographic surgi-guide (bone-, mucosa- and teeth-supported) for both osteotomy site preparation and implant delivery. Ten adults were included in this study. Six patients were treated in both arches, and the number of computer aided implantology (CAI) interventions was 16, which equalled the number of guides used, for a total of 111 implants inserted. Complications and unexpected events occurred during the positioning of the surgical guide and whilst preparing the implant site and installing implants. In order to minimize the risk of complications and unexpected events, attention must be paid to every stage of treatment, including checking computed tomography (CT) images, guide manufacturing, proper guide positioning in the mouth, guide fixation, rotational allowance of drill in tubes, shape and sharpness of the drills, first entry point, mouth opening and guided implant insertion.

The Influence of the Tolerance between Mechanical Components on the Accuracy of Implants Inserted with a Stereolithographic Surgical Guide: A Retrospective Clinical Study

BACKGROUND The stereolithographic-guided surgery system involves a sequence of diagnostic and therapeutic events, and errors can arise at different stages. In these systems, one of the potentially clinically relevant errors may be the mechanical errors caused by the bur-guide gap due to the presence of a rotational allowance of the drills in the tubes. PURPOSE The purpose of this retrospective clinical study is to determine if it is possible to reduce the total error by limiting the tolerance among the mechanical components and to evaluate its clinical incidence. MATERIALS AND METHODS Sixty-six implants were inserted using the External Hex Safe® (Materialise Dental, Leuven, Belgium) system (Group A), and 71 implants were inserted using the same system with mechanical components modified to minimize the tolerance (Group B). Regarding only the angular deviation values, the t-test was used to determine the influence of reduced tolerance among the mechanical components on the accuracy values. RESULTS t-Test showed that there is a statistically significant better accuracy with the modified system (Group B). CONCLUSIONS Limiting the error that originates from mechanical components, total error could be statistically significantly reduced. Mechanical error is one of the most important source of error using External Hex Safe stereolithographic surgical guide.

Accuracy of positioning of implants inserted using a mucosa-supported stereolithographic surgical guide in the edentulous maxilla and mandible.

PURPOSE The aim of this study was to evaluate the accuracy of implants inserted using a mucosa-supported stereolithographic surgical guide and to determine the influence of surgical management of the guide (fixed or unfixed), arch (maxilla or mandible), and smoking habit (normal or hyperplastic mucosa) on accuracy. MATERIALS AND METHODS In completely edentulous subjects, preoperative computed tomography (CT) was performed, and the images were used to plan implant positions. After the implants were placed, CT was performed again, and the presurgical and postoperative images were compared. With computer software, the jaw contours from the two CT scans were matched and the deviations between the planned and actual implant positions were evaluated. Surgical technique, arch, and smoking habit were examined as independent variables, and their influence on accuracy was evaluated with a t test. RESULTS Twenty-eight surgical guides (225 implants) were included in this study. Deviations between planned and actual positions were seen in the global coronal (mean±SD: 1.68±0.6 mm), global apical (2.19 ± 0.83 mm), and angular (4.67 ± 2.68 degrees) dimensions. Fixation of surgical guides (fixed: 4.09 degrees; not fixed: 5.62 degrees) and use of the guide in the maxilla (4.36 degrees; mandible: 5.46 degrees) resulted in statistically significantly less angular deviation (ie, better accuracy). Nonsmoking patients showed statistically significantly better accuracy in global coronal (nonsmokers: 1.54 mm; smokers: 1.83 mm) and global apical (nonsmokers: 2.08 mm; smokers: 2.27 mm) deviations. CONCLUSION The greater supporting surface of the maxilla and fixation of the surgical guide improved the accuracy of the guides. The reduced mucosa thickness in nonsmokers decreased global coronal and global apical deviation.

Is it possible to improve the accuracy of implants inserted with a stereolithographic surgical guide by reducing the tolerance between mechanical components

When using a stereolithographic surgical guide, a potentially clinically relevant error may be the mechanical error caused by the bur guide cylinder gap due to the presence of a rotational allowance of drills in the tubes. The aim of the present study was to determine if it is possible to reduce the total error by limiting the tolerance among the mechanical components and to evaluate its clinical incidence. Sixty implants were inserted in eight totally edentate subjects using the External Hex Safe(®) system with mechanical components modified to minimize the tolerance. Pre- and postoperative computed tomography images were compared, and the angular deviation was calculated between the planned and the placed implants. The mean angular deviation was 2.02° (range 0.81-3.48°; standard deviation 0.87). The results of the present study show that by limiting the error that originates from mechanical components, the total error could be significantly reduced.

Accuracy of a computer-aided implant surgical technique.

The purpose of this in vivo retrospective study was to evaluate the accuracy of a computer-designed stereolithographic surgical guide. One hundred eleven implants were placed in 10 patients. Pre- and postoperative computed tomography images were compared using specific software. Global, angular, depth, and lateral deviations were calculated between planned and placed implants. Mean global deviations between planned and placed implants at the coronal and apical aspects were 1.52 mm (range, 0.13 to 3.00 mm) and 1.97 mm (range, 0.34 to 4.23 mm), respectively, while the mean angular deviation was 4.68 degrees (range, 0.10 to 15.25 degrees). This study highlighted a reasonable mean accuracy with relatively high maximum deviations between the postoperative position and the preoperative plan. These results should serve as a warning for the clinician if implants are placed near vital structures.

Clinical, Radiographic, and Histologic Evaluation of Maxillary Sinus Lift Procedure Using a Highly Purified Xenogenic Graft (Laddec(®)).

ABSTRACT Objectives The aim of this study was to evaluate the clinical, radiographic and histologic results when a highly purified xenogenic bone (Laddec®) was used as grafting material in maxillary sinuses. Material and Methods In fifteen patients requiring unilateral maxillary sinus augmentation, the grafting procedure was performed with Laddec®. Forty-two implants were installed after a 6 month healing period. The height of the augmented sinus was measured radiographically immediately after augmentation and postoperatively up to 36 months. At the time of implant placement, a bone core was harvested in each patient for histological examination. Results The cumulative implant survival rate was 97.6%. The original height was 3.65 (SD 0.7) mm and the augmented sinus height was 13.8 (SD 1.4) mm after the surgery. The reduced height of grafted xenogenic material (RDL) at the implant insertion was 0.83 (SD 0.38) mm, and at the final postoperative visit was 0.91 (SD 0.25) mm, showing no significant correlation with the follow-up periods by Spearman’s test (P = 0.118). In addition, no significant difference in the RDL was observed according to the site of implantation (P = 0.682). The mean implant marginal bone loss was 0.38 (SD 0.24) mm. Histological analysis showed the bone cores were composed of 64.72 (SD 3.44)% newly formed bone, 17.41 (SD 2.02)% connective tissue, 16.93 (SD 2.83)% residual graft particles, and 0.94 (SD 0.11)% inflammatory cells. Conclusions According to our data, the highly purified xenogenic bone (Laddec®), used as graft material in the sinus lift procedure, may create adequate bone volume, and appropriate osseointegration of dental implants.

Factors Influencing the Soft Tissue Changes Around Single Laser Microtextured Implants-Abutments in the Anterior Maxilla: A 5-Year Retrospective Study.

Purpose:The aim of this study was to evaluate the possible factors that influenced the periimplant soft tissue changes around single implants-abutments with laser-microtextured surface (LMS) in the esthetic zone. Materials and Methods:Thirty-nine units, formed by implant-abutment with LMS were studied. Variables possibly associated with the periimplant soft tissue changes were obtained from clinical measurements (plaque [present/absent], periimplant biotype [thin/thick], and probing depth); intrasurgical measurements (vertical height in millimeters of the keratinized gingiva in the vestibular part of the implant site vestibular keratinized gingiva [VKG], implant vestibular crestal exposition, vestibular crestal level, and vestibular bone width); cast models (implant position [buccal/palatal], implant abutments angle); periapical radiographs (distance from the contact point to the interproximal bone crest of the adjacent tooth [CP-BC], distance from the contact point to the implant platform [CP-P], distance from the contact point to the first bone to implant contact [CP-IB]); and digital clinical photographs. Fisher exact test was used to determine the influence of each factor on the papilla level and on the facial marginal mucosal level. Results:The papillae level at the implant sites was significantly associated with the distance from the contact point to the alveolar bone crest, whereas no association was found with other variables. Periimplant biotype, differences in the VKG, CP-BC, and CP-IB were found associated with the different facial marginal mucosal level groups. Conclusions:This study showed that the papilla level at single-tooth implants-abutments with LMS in the anterior maxilla was mainly influenced by the interproximal bone crest level of the adjacent tooth, whereas the marginal mucosal level was affected by periimplant biotype, facial bone crest level, and crestal implant exposition.

Bone Healing in Extraction Sockets Covered With Collagen Membrane Alone or Associated With Porcine-Derived Bone Graft: a Comparative Histological and Histomorphometric Analysis

ABSTRACT Objectives The present paper reports data of a randomized study aimed to analyse and compare the histologic and histomorphometric aspects of bone healing in extraction sites covered with collagen membrane alone or associated with porcine-derived bone graft. Material and Methods Thirty patients, with single extraction sockets without severe bone wall defects in the premolar/molar region, were included. Ten extraction sockets were grafted with porcine-derived bone and covered with collagen membrane (group 1), 10 sites were covered with collagen membrane alone (group 2), and 10 sites healed spontaneously (group 3). After 4 months of healing, 26 (8 in group 1, 9 in group 2, and 9 in group 3) bone core specimens were harvested for histologic evaluation, then dental implants were placed. Results Sites in the group 1 and in the group 2 showed similar histologic and histomorphometric results without significantly differences in the percentage of vital bone (57.43% [SD 4.8] vs. 60.01% [SD 3.2]), and non-mineralized connective tissue 22.99% (SD 5.3) vs. 18.53% (SD 6.2). In group 1 a 16.57% (SD 3.8) of residual material was found. Conclusions Results showed that the use of collagen membrane alone or associated to porcine-derived bone improves the healing bone process compared to that of extraction sites spontaneously healed. Moreover, histomorphometric data related to bone quality, indicated that extraction sites without severe walls defects and with a vestibular bone thickness > 1.5 mm, treated with a low resorbtion rate collagen membrane alone, do not need more than 4 months for dental implant insertion.