Ugo Covani

Osteotomy and membrane elevation during the maxillary sinus augmentation procedure. A comparative study: piezoelectric device vs. conventional rotative instruments.

OBJECTIVES The aim of the present study was to investigate in a randomized-controlled clinical trial the performance of rotary instruments compared with a piezoelectric device during maxillary sinus floor elevation. MATERIALS AND METHODS Thirteen patients who required a bilateral maxillary sinus augmentation for implant-prosthetic rehabilitation were included in this study. A within-patient control study was carried out. The osteotomy for sinus access was performed on one side of the maxilla using the piezosurgery (test sites) and on the other side using conventional rotary diamond burs (control sites). The parameters recorded were as follows: bony window length (L), bony window height (H), bone thickness (T) and osteotomy area (A)--calculated by multiplying L and H. In addition, the time necessary for the osteotomy and sinus membrane elevation as well as the number of surgical complications were calculated. RESULTS The mean length and height of the bone window were similar in both groups. The osteotomy area (A) obtained by multiplying L and H was wider in the control group (151.2 +/- 20.4 mm(2)) compared with the test group (137 +/- 24.2 mm(2)). The time necessary for the osteotomy and the sinus membrane elevation with conventional instruments was 10.2 +/- 2.4 min, while with the piezoelectric device it was 11.5 +/- 3.8 min. Moreover, membrane perforation occurred in 30% of the maxillary sinuses in the test group and in 23% of the control group. None of the differences observed between the two groups reached a level of significance. CONCLUSIONS Within the limits of the present study, it may be concluded that piezosurgery and conventional instruments did not show any differences in the clinical parameters investigated for the maxillary sinus floor elevation.

Tissue changes of extraction sockets in humans: a comparison of spontaneous healing vs. ridge preservation with secondary soft tissue healing

INTRODUCTION As a consequence of extraction, the height of the buccal wall tends to decrease and results in the disappearance of bundle bone. To modify bone remodelling after extraction, various ridge preservation techniques have been proposed. The present research was drawn up with the following considerations in mind: to evaluate and to compare changes of hard and soft tissues in post-extraction sockets which received a ridge preservation procedure, with post-extraction sockets which had healed naturally. MATERIALS AND METHODS Each patient was randomly allocated to a test or control group using a specific software package. After extraction, the sockets were carefully inspected and any granulation tissue was removed. The control sites received silk sutures to stabilize the clot without any grafting material. The test sites were grafted with corticocancellous porcine bone and a collagen membrane. All experimental sites had the membranes left exposed to the oral cavity with a secondary wound healing. The thickness of the buccal alveolar bone, if present, was carefully measured at the time of tooth extraction using a calliper at 1 mm from the edge of the wall. The following clinical parameters were evaluated at baseline and after 4 months at implant placement: vertical bone changes, horizontal bone changes and width of keratinized gingiva. The length, diameter and need for additional bone augmentation were assessed for both groups at the time of implant insertion. RESULTS The control group showed vertical bone resorption of 1 ± 0.7 mm, 2.1 ± 0.6 mm, 1 ± 0.8 mm and 2 ± 0.73 mm at the mesial, vestibular, distal and lingual sites respectively. Moreover, changes in horizontal dimension showed an average resorption of 3.6 ± 0.72 mm. The test sites showed a horizontal bone remodelling of 0.3 ± 0.76 mm, 1.1 ± 0.96 mm, 0.3 ± 0.85 mm, 0.9 ± 0.98 mm at the mesial, vestibular, distal and lingual sites respectively. The horizontal bone resorption at the test sites was 1.6 ± 0.55 mm. The keratinized gingiva showed a coronal shift of 0.7 mm in the control group when compared to 1.1 mm in the test group. In addition, 42% of sites in the control group required an additional bone augmentation at implant placement, when compared to 7% in the test sites. CONCLUSIONS This study clearly points out that an alveolar ridge preservation technique performed with collagenated porcine bone and a resorbable membrane--according to the procedure reported in this study--was able to limit the contour changes after tooth extraction. Finally, the test sites showed a better preservation of facial keratinized tissue when compared to control sites; grafted sites allowed the placement of longer and wider implants when compared to implants inserted in non-grafted sites.

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.

Deep-Frozen Allogeneic Onlay Bone Grafts for Reconstruction of Atrophic Maxillary Alveolar Ridges: A Preliminary Study

PURPOSE The purpose of this article was to evaluate the suitability of deep-frozen allograft for ridge augmentation procedures in severely atrophic maxillae and to evaluate the clinical success of dental implants inserted after grafting and before prosthetic rehabilitation. PATIENTS AND METHODS This study included 13 patients (3 men and 10 women) aged 36 to 65 years. All the patients selected for this study required bone augmentation procedures because of severe alveolar ridge atrophy and were scheduled for onlay bone allograft and titanium implants in a 2-stage procedure. The dental implants were inserted 5 months after grafting. The follow-up period for the implants was 6 months after placement at the second stage of implant surgery. RESULTS A total of 24 onlay block allografts were used to augment atrophic maxillae in 13 patients. Of the 24 onlay block allografts, 5 were scheduled for vertical alveolar ridge augmentation and the remaining 19 for horizontal alveolar ridge augmentation. Early exposure of the onlay bone graft was observed in 2 patients. All the block grafts showing early exposure had to be completely removed because of infection. All the observed complications were associated with onlay bone grafts placed to increase the vertical dimension of the alveolar ridges. Thirty-eight implants ranging in length from 10 to 15 mm were placed in the area of bone augmentation. All implants inserted achieved satisfactory primary stability. Two implants failed to integrate 6 months after placement during the second stage of surgery. The failed implants were successfully replaced without any need for additional bone grafting. CONCLUSIONS The use of block allografts to treat maxillary atrophy yielded successful outcomes. Moreover, the augmentation procedure allowed the insertion of implants in the grafted area 5 months after surgery. Therefore, on the basis of this preliminary study, deep-frozen bone allograft can be considered a promising treatment for severe maxillary atrophy, with more extensive follow-up studies being needed to confirm these preliminary data.

Clinical evaluation of a ridge augmentation procedure for the severely resorbed alveolar socket: multicenter randomized controlled trial, preliminary results

OBJECTIVE To radiographically analyze extraction sites left untreated or treated using a socket preservation technique. MATERIALS AND METHODS A total of 20 patients scheduled for single extraction in the maxilla from second to second premolar were enrolled in this study. All sites showed a bone defect >5 mm at the buccal wall and no soft tissue recession. At baseline (T0), tooth extraction was performed; subsequently, sites were randomly allocated to the control (CG: left to heal without grafting) or test group (TG: grafted using hydroxyapatite). Two months later (T1), implants were inserted and eventual GBR procedure was performed. Three months later, the definitive crown was placed. Follow up was 24 months (T2). A cone-beam computed tomographic examination (CT) was performed at each time point. At each radiographic analysis, horizontal and vertical widths of the sockets were measured. Comparisons between CG and TG were performed by a Wilcoxon non-parametric test. RESULTS At the end of the study, no patient dropped out and all implants inserted (10 in each group) resulted integrated. GBR procedures were performed at T1 only in the CG. In the CG, the mean value of the horizontal width in the coronal CT slices was 0.98 mm (± 0.37), 7.70 mm (± 0.92), 7.45 mm (± 0.69) at T0, T1 (after bone regeneration) and T2, respectively. In the TG, the mean value of the horizontal width in the coronal CT slices was 0.96 mm (± 0.41), 8.97 mm (± 1.91), 9.48 mm (± 1.56); at T2, it was 9.52 mm (± 1.87) at T0 (pre- and post-socket preservation) T1 and T2, respectively. At each follow up, the mean horizontal bone width in TG was statistically significantly greater than in the control group (P < 0.05). At T0, mean value of the vertical bone defect length (BDL) was 6.93 mm for TG, 6.5 mm for CG. At T1 and T2, mean BDL value was 0 for both groups. Statistically significant difference was not found between TC and CG at any time point (P > 0.05). CONCLUSIONS This randomized controlled trial suggested that in sites with buccal bone defects >5 mm, the application of HA can minimize alveolar crest resorption following tooth extraction. Furthermore, compared with traditional regenerative procedure carried out following socket healing, this preservation technique seems to result in better horizontal regeneration of the buccal bone wall.

A Randomized Clinical Evaluation of Ultrasound Bone Surgery Versus Traditional Rotary Instruments in Lower Third Molar Extraction

PURPOSE The purpose of this study was to investigate and compare, in a randomized and controlled clinical trial, the use of ultrasound bone surgery devices and the use of rotary instruments in lower third molar extractions. MATERIALS AND METHODS We selected 26 patients (12 women and 14 men) for this study; the mean age was 31.2 years (range, 24-45 years). A randomized clinical trial was planned. Patients in the control group received treatment with the conventional rotary instruments; patients in the test group received treatment with the ultrasound bone surgery tools. Twenty-six third molars were allocated to the test and control groups according to a computer-generated randomization list. All the surgical procedures were performed by the same surgeon. Pain, trismus, cheek swelling, and number of analgesics taken were evaluated at baseline (before surgery) and at the first-, third-, fifth-, and seventh-day visits. RESULTS Pain levels (evaluated on a visual analog scale) were higher in the control group when compared with the ultrasonic group; however, no statistically significant differences were found. On the contrary, the number of analgesics taken in the test group was significantly lower when compared with the control group. The occurrence of trismus was significantly higher in the control group when compared with the test group. The clinical values of cheek swelling were higher in the rotary group when compared with the ultrasound group at the fifth-day visit. CONCLUSION This study showed that the use of ultrasound bone surgery for third molar extraction significantly reduced the occurrence of postsurgical trismus, the occurrence of swelling, and the number of analgesics taken after surgery.

New Directions in Surgical Endodontics: Immediate Implantation into an Extraction Socket

Endodontic surgical procedures may reveal compromising factors that indicate a modification of the treatment (e.g. tooth extraction, root amputation, etc.). To take advantage of the osseous height and width, as well as the natural tooth angulation, immediate placement of implants after extraction is a reasonable alternative treatment. In this study, 32 titanium alloy implants were inserted immediately after extraction of teeth diagnosed during endodontic surgery as having root fractures, perforations, or endodontic-periodontal complications. After 4 to 6 months of osseointegration, only one implant failed to integrate, and the remaining implants were prosthetically restored. Sixteen months after occlusal loading, bone loss was approximately 1.5 mm for the 31 implants remaining. It seems that the immediate placement of implants following tooth extraction due to endodontic complications is a reliable procedure.

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.

Analysis of the pattern of the alveolar ridge remodelling following single tooth extraction.

INTRODUCTION Tooth extraction is followed by marked osseous changes of the residual alveolar ridge including severe bone alterations both in height and in width. However, such remodelling could jeopardize the subsequent implant insertion for two main reasons. Firstly, the absence of adequate bone levels makes implant placement impossible; secondly, aesthetic problems in the fabrication of implanto-supported restoration could be caused by serious bone re-absorption. Thus, it is of crucial importance that the dental surgeon knows how the alveolar crest changes when a single tooth has been removed. The aim of this study was to evaluate the pattern of alveolar crest remodelling observed in a single intercalated area of tooth extraction after at least a period of 6 months of healing, using standardized photos of model casts. MATERIAL AND METHODS Among the patients who were treated for a single intercalated tooth extraction during the last 2 years at the department of dentistry at Versilia Hospital, Lido di Camaiore (Lucca), Italy, we selected 50 patients. The amount of alveolar crest remodelling was assessed on standardized photos of study models. All measurement were recorded on an Excel sheet (Excel, Windows XP(®)) and each value was multiplied by the enlargement index so that true values of re-absorption could be obtained. Finally, we have calculated the percentage of amount of alveolar crest remodelling and shifting of alveolar crest. RESULTS We calculated the percentage of buccal remodelling and alveolar crest shift. The buccal re-absorption was 19.4 ± 9.4% at mesial point, 39.1 ± 10.4% at midpoint and 20.3 ± 10.7% at distal level. Moreover, the shift of the alveolar crest was 59.1 ± 11.2% at mesial point, 64.8 ± 10.5% at the midpoint and 56 ± 12.5% at distal point. CONCLUSIONS This study confirmed that buccal wall tends to re-absorb after the extraction according to a specific pattern. Thus, the re-absorption at the midpoint represent the double of bone loss at the distal and the mesial points. Furthermore, we have observed first how the alveolar crest shifts placing along the more lingual/palatal line which divides the original alveolar crest into three parts.

Extraction Socket Healing in Humans After Ridge Preservation Techniques: Comparison Between Flapless and Flapped Procedures in a Randomized Clinical Trial

BACKGROUND The preservation of hard and soft tissue volume, partially lost after tooth removal, can potentially reduce the need for the more demanding augmentation procedures used in implant-supported rehabilitation. The objective of this research study is to investigate the effect of filling with xenogeneic material the postextractive sockets of two surgical procedures (flapless versus flapped). METHODS In this prospective randomized clinical survey, two types of socket preservation were performed on two groups of patients: the control, treated via full-thickness mucoperiosteal flap, and the test, via a flapless procedure. Anatomic measurements and related outcome variables at the third month were analyzed using multiway analysis of variance. Multiple comparison tests, using Tukey honestly significant difference test, and appropriate pairwise comparison tests for independent samples were carried out. RESULTS Sixty-four patients were treated, 32 for each of the two socket preservation procedures. Statistically significant differences were registered for the output variables -- changes in width of keratinized gingiva, changes in bucco-lingual width, and vertical bone changes at four sites -- between the two socket preservation techniques, with P values of <0.001, <0.001, and 0.0105, respectively. CONCLUSIONS A full-thickness mucoperiosteal flap gave significantly more negative results than that of the less-demanding flapless procedure, with an increased width resorption of the postextraction site. Moreover, the increased value of the keratinized gingival width attested to the positive outcome of a flapless procedure in terms of soft tissue preservation and improvement. On the other hand, the flapped technique seemed to show less vertical bone resorption on the buccal aspect than the flapless technique.