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Replacing the missing maxillary anterior teeth with dental implants and maintaining the soft tissue structure and alveolar profile is an esthetic challenge for the restorative dentist. This clinical report describes the immediate provisional placement and prosthetic rehabilitation of 2 missing maxillary central incisors with scalloped dental implants.
The purposes of the present study were: 1) to investigate the biocompatibility of a natural resin (made of fatty acids extracted from Ricinus communis) implanted in the dental alveolus of rats and 2) to verify any possible interference of that material in the osseous healing following tooth extraction. The resin (AUG-EX, Poliquil Araraquara Polímeros Químicos LTDA, Araraquara--SP) was placed inside de alveoli immediately after extraction of the upper right incisors. The animals were sacrificed 1, 2, 3 and 6 weeks after extraction or extraction + implantation. The hemi-maxillae were decalcified and processed for paraffin embedding. Longitudinal 6-micrometer-thick semi-serial sections stained with hematoxylin and eosin were obtained. Histologic examination showed particles of irregular shape and variable size (700-1200 microns) localized in the medium/cervical alveolar thirds, with a scanty but persistent foreign body reaction. From the second week on, as the relative volume of bone trabeculae increased, it was seen in close contact with the surface of the implanted material in some regions. Histometric analysis (differential point counting method), used to quantify the healing process in the apical third, showed a small but significant decrease (13%-20%) in new bone formation in the implanted rats. In conclusion, the results show that, in spite of its biocompatible nature, the studied resin hinders the post-extration healing process.
Elephant tusk removal usually requires costly surgical procedures that are time-consuming and present a significant risk to the animal when performed using general anesthesia. Such techniques require gauges, chisels, and forceps to remove the tusk. This article reports the simple removal of the tusk of an 18-yr-old African elephant (Loxodonta africana) without the use of surgical instruments and anesthesia. Rubber elastics were placed around a tusk, causing loss of alveolar bone with subsequent exfoliation of the tusk within 3 wk. The healing process was uneventful.
This study evaluated new bone formation in human extraction sockets treated with demineralized freeze-dried bone allografts (DFDBA) and celloc occlusive membranes. Hard tissue biopsies of 7 sites in 6 patients were obtained 14 weeks to 13 months following extraction and grafting. Histologic analysis revealed that individual particles of DFDBA were discernible up to 13 months in situ. In all samples, all particles of DFDBA were well incorporated within new bone, which exhibited osteocyte-containing lacunae. Distinct cement lines clearly demarcated the DFDBA particles from the surrounding, intimately-apposed woven and lamellar bone. The marrow demonstrated a mild degree of fibrosis without signs of inflammatory reaction. There was also a notable lack of fibrous encapsulation of the allograft, and little osteoclasis was observed. Our findings demonstrate that commercially available DFDBA has the potential to function physically as a nidus for appositional new bone growth in alveolar sockets following tooth extraction. Further investigations of the biological activity of DFDBA in situ are warranted.
Use of combination antiretroviral therapy regimens, including a protease inhibitor, has greatly improved the survival and systemic health of HIV-positive patients. Due to the esthetic requirements of the patient in this case report, placement of an endosseous implant into a fresh extraction site, restored with a single crown, was the treatment of choice. The implant and restoration are functioning well 18 months after placement of the fixture.
This prospective clinical trial evaluated 134 implants in 81 patients. The implants were placed at the time of tooth extraction and were not augmented with barrier membranes or graft materials. The implants were placed into good jaw bone anatomy and quality and were restored by dentists familiar with the implant system. Forty-seven implants were followed between 4 to 5 years with a cumulative success rate of 93.3%. Marginal bone levels were measured for 61 patients with 108 implants. The average mesial-distal measurements for maxillary implants at abutment connection were 1.02 mm (SD+/-0.59) and 1.36 mm (SD+/-0.78) at an average of 32 months follow-up. These differences were not significant. The average mandibular mesial-distal measurements at abutment connection were 1.05 mm (SD+/-0.92) and 1.54 mm (SD+/-0.91) at follow-up. These differences were statistically significant (P = 0.0027). Removal of one patient (5 implants) with advanced marginal bone loss from the data provided a marginal bone level of 1.20 mm (SD+/-0.94) at abutment connection and 1.30 mm (SD+/-0.87) at follow-up. These differences were not significant. The results of this study indicate that implants placed at the time of extraction without augmentation or grafting have excellent long-term cumulative success rates.
BACKGROUND: Lyodura has been used in periodontology and maxillofacial surgery to overcome different clinical conditions. The use of lyodura to induce new bone formation in humans has not been widely reported. The purpose of this article is to describe the use of lyodura as a resorbable barrier to promote bone formation in osseous defects around dental implants. METHODS: The study group consisted of 22 healthy patients (12 women and 10 men), with a mean age of 32 (range 20 to 45). A total of 44 implants (9 titanium screw-type and 35 hydroxyapatite-coated cylinder implants) were placed. Of these, 27 implants were placed in the maxilla and 17 in the mandible. At 27 extraction sites bony vertical defects were measured on the buccal, lingual, mesial and distal sides of the implant. In the remaining 17 cases, where either immediate or staged implantation was performed, and a dehiscence was present, its vertical length was measured from the alveolar crest. All bony defects were grafted with autogenous bone harvested from the tuberosity. Each site was covered with lyodura. RESULTS: Healing was uneventful; no inflammation, infection, or soft tissue dehiscence was observed. At all extraction sites and in 76% of the dehiscence defects, hard tissue appearing clinically similar to bone completely filled the defect. Of those defects not completely filled, a mean vertical bone increase of 2.5 mm was recorded. A mean vertical bone increase of 2.6 mm was achieved at extraction sites and a mean increase of 2.79 mm was achieved at dehiscence sites. CONCLUSIONS: Lyodura can safely and effectively be used for guided bone regeneration at both extraction sites and for dehiscence defects.
BACKGROUND: Guided bone regeneration (GBR) has been widely utilized for the promotion of bone augmentation in bone loss areas. However, little information has been available regarding chronological changes in newly formed bone and alterations in the nature of newly formed bone after removal of a barrier membrane. The present study attempted to establish a GBR model for rat maxillae. We also examined the effects of membrane application periods on newly formed bone and its remodeling process after removal of the membrane in this experimental model. METHODS: Thirty-five Wistar rats were divided into 2 groups: a membrane application group and a membrane removal group. The chronological changes of newly formed bone were evaluated histologically and statistically. RESULTS: At 2 weeks after the GBR procedure, bony cavities had completely filled the newly formed bone in the experimental side. In the control side, corticalization on the surface of the newly formed bone proceeded with a decrease in the bone marrow cavity, whereas the bone marrow space had enlarged by 12 weeks post-surgery in the experimental side. In the membrane removal group, the osteoblasts appeared on newly formed bone at 1 week after membrane removal. Comparatively thick compact bone had formed on the surface of the newly formed bone at 4 weeks after membrane removal, and corticalization proceeded later. CONCLUSIONS: The long-term application of a barrier membrane induces the enlargement of the bone marrow spaces. We suggest that PTFE membrane removal in adequate time promotes the corticalization and maturation of the newly formed bone by the GBR technique.
BACKGROUND: Studies concerning immediate implantation describe its use in the anterior and premolar regions. However, its clinical effectiveness in immediately replacing molar teeth has rarely been challenged. The purpose of this study was to evaluate the survival rate of implants placed immediately after extraction of molar teeth to support a fixed ceramo-metal prosthesis. METHODS: From 1989 to 1996, 56 immediate implants were placed in 43 patients following extraction of 51 molars; 46 molars were replaced by 1 implant and 5 molars replaced by 2 implants. All implants were restored with fixed prostheses (4 single crowns and 52 splinted). Mean follow-up period was 15 months (range, 4 to 60 months). The influence of the following parameters on implant failure was evaluated: gender, arch, smoking, pre-extraction vertical bone loss, implant length, and severity of complications between the two stages of surgery. RESULTS: The 5-year cumulative survival rate (5-year CSR) was 89%. The 5-year CSR among men was 84% compared to 93.5% among women. The maxillary 5-year CSR was 82% and the mandibular 92%. Among non-smokers (50 implants), the 5-year CSR was 90% compared to 83% among smokers (6 implants). Complications were evident in 8 (6 minor, 2 major) out of 50 non-failing implants compared to 2 (minor) of the 6 failing implants. No differences were evident in the other study variables. CONCLUSIONS: Immediate implantation in the molar region is an alternative, predictable surgical treatment. Immediate implantation in the posterior mandible has a better prognosis than in the posterior maxilla.
Alveolar ridge deformities are usually the result of trauma, periodontal disease, surgical insult, or developmental defects. Preventing ridge collapse with the extraction of maxillary anterior teeth is vital to an esthetic restorative result. Several techniques are available to prevent ridge collapse. In these case presentations, ridge preservation was achieved utilizing an acellular dermal matrix as a barrier membrane with a demineralized freeze-dried bone allograft. This report demonstrated an acceptable esthetic result with no loss of ridge height or width. Soft tissue dimensions were also preserved. The two graft materials were well accepted by the body and healing was rapid and without significant discomfort. The technique illustrated provides the surgeon with another option to prevent ridge collapse and ultimately improve esthetics.
When maxillary anterior teeth are extracted, subsequent ridge collapse can significantly compromise esthetics. Preservation of an adequate volume of bone is vital to successful implant placement. Ridge preservation achieved utilizing an acellular dermal matrix as a barrier membrane with a demineralized freeze-dried bone allograft has been previously reported. In this case presentation, guided bone regeneration was achieved around an immediate endosseous implant when this same technique was used. As in the previous case reports, this technique demonstrated an acceptable esthetic result with virtually no loss of ridge height or width. Soft tissue dimensions were also preserved. Both the hard and soft tissue grafts were well accepted by the body and healing was rapid and without significant discomfort. This surgical technique provides the clinician with an option to provide immediate implant therapy when primary closure cannot be achieved.
BACKGROUND: Myospherulosis of the oral cavity is an inflammatory, granulomatous lesion historically associated with the use of petrolatum-based antibiotic ointment placed in third molar extraction sites to prevent postoperative infection. METHODS: A case of bilateral myospherulosis is presented, in which large lesions complicated the procurement of a cortical block graft used to prepare a mandibular molar edentulous space for implant placement. By obtaining the block graft from a more lateral location on the mandible, an adequate graft was procured and was successfully grafted into an atrophic edentulous ridge. RESULTS: The cortical block graft was successfully incorporated by the recipient site, which received a wide-body, threaded dental implant 6 months later. Healing was uncomplicated, and a functional implant-supported restoration was successfully achieved. CONCLUSIONS: Myospherulosis, though rare today, may present a significant obstacle to the procurement of cortical block grafts. In this case, thorough debridement of the material resulted in subsequent healing of the myospherulosis defect, but prevented procurement of the cortical graft from the planned site. The dimension and volume of the neighboring cortical bone were adequate, and the augmented edentulous space was subsequently restored with a functional endosseous implant. The success seen in these 2 sites would seem to confirm the assumption that size and location of myospherulosis defects are critical factors in obtaining a successful clinical result in implant patients.
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BACKGROUND: Implant restoration of the posterior maxilla poses significant challenges to the clinician. In an effort to increase the apical occlusal dimension of available bone for implant placement, a number of sinus augmentation approaches have been suggested. This paper describes a simplified technique for predictable sinus augmentation at the time of maxillary molar extraction. METHODS: A modified trephine and osteotome technique was utilized to implode the interradicular bone following maxillary molar extraction. Particulate material and a membrane were then placed to maximize regeneration of alveolar bone. RESULTS: One hundred sixty-seven (167) implants were subsequently placed in regenerated bone following the above technique. One hundred thirty-seven (137) of these implants were restored and in function for up to 3 years at the time of statistical compilation, and 136 of the 137 implants were functioning successfully by the Albrekteson criteria for a cumulative success rate of 97.8%. CONCLUSIONS: The technique presented for simultaneous sinus augmentation at the time of molar extraction, followed by subsequent implant placement after maturation of regenerating tissues, demonstrates a high success rate for up to 3 years in function. Long-term studies may be useful in evaluating the continual efficacy of such an approach.
BACKGROUND: It has been shown that the amount of healed bone following guided bone regeneration (GBR) with demineralized freeze-dried bone allograft (DFDBA) and a bioabsorbable membrane is significantly less than the initial quantity. A study was designed to determine if the amount of GBR would be affected by using an osteoinductive DFDBA and bioabsorbable membrane and membrane stabilization. METHODS: Eleven extraction sites (10 patients) were treated with DFDBA and bioabsorbable membrane before placing endosseous implants. Standardized alveolar height and width measurements were taken after extraction, GBR, and 4 months postoperatively, at predetermined measurement points (sites midpoint and 3 mm mesial and distal from the midpoint) and classified as augmented (<1 mm increase of GBR height or width) or grafted (>1 mm increase). Five membranes were stabilized. RESULTS: Three mm from the crest, augmented points exhibited a complete loss of augmented width. There was also some loss of pre-GBR bone width (ranging from 4.7% to 20%) at augmented and grafted points. Five mm from the crest, augmented points lost 83.3% to 92.3% of augmented width and grafted points lost 12.9% to 18% of pre-GBR width. Loss of augmented height ranged from 93.5% to 100%. Augmented (except distal) and grafted measurement points lost 2.1% to 12% of pre-GBR height. Comparing tacked and non-tacked sites, the former manifested less loss of augmented bone width, the latter augmented bone height. CONCLUSIONS: Results indicate a complete loss of augmented width 3 mm from the crest and almost complete loss in height and width 5 mm from the crest. Membrane stabilization appeared beneficial.
BACKGROUND: Zirconia might be an alternative material to titanium for dental implant fabrication. The aim of the present study was to investigate the histological behavior (osseointegration) of loaded zirconia implants in an animal model and to compare it with the behavior of titanium implants. METHODS: Five months after extraction of the upper anterior teeth, 12 custom-made titanium implants (control group) and 12 custom-made zirconia implants (test group) were inserted in the extraction sites in six monkeys. Before insertion, the titanium implant surfaces were sandblasted with Al2O3 and subsequently acid-etched. The zirconia implants were only sandblasted. Six months following implant insertion, impressions were taken for the fabrication of single crowns. A further 3 months later, nonprecious metal crowns were inserted. Five months after insertion of the crowns, the implants with the surrounding hard and soft tissues were harvested, histologically prepared, and evaluated under the light microscope regarding the peri-implant soft tissue dimensions and mineralized bone-to-implant contact. RESULTS: No implant was lost during the investigational period. The mean height of the soft peri-implant tissue cuff was 5 mm around the titanium implants and 4.5 mm around the zirconia implants. No statistically significant differences were found in the extent of the different soft tissue compartments. The mean mineralized bone-to-implant contact after 9 months of healing and 5 months of loading amounted to 72.9% (SD: 14%) for the titanium implants and to 67.4% (SD: 17%) for the zirconia implants. There was no statistically significant difference between the different implant materials. CONCLUSION: Within the limits of this animal experiment, it can be concluded that the custom-made zirconia implants osseointegrated to the same extent as custom-made titanium control implants and show the same peri-implant soft tissue dimensions.
BACKGROUND: Alveolar bone changes following tooth extraction have been well documented and have given rise to a number of treatment approaches. Included in these approaches are placement of various grafting materials, immediate implant placement, and a combination of both. METHODS: A review of all pertinent literature discussing regenerative therapy at the time of tooth extraction or immediate implant placement with or without concomitant regenerative therapy was carried out. RESULTS: A clinically-based hierarchy of treatment selection following extraction of single rooted teeth is proposed, based upon the available literature and clinical experience. The role of patient phenotype is considered. CONCLUSION: Utilization of the proposed hierarchy of treatment selection affords a logical framework within which to predictably treat a variety of patients.
BACKGROUND: The purpose of this study was to evaluate the predictability of implant placement at the time of maxillary molar extraction using a modified insertion technique and implant design. METHODS: At the time of maxillary molar extraction, 83 tapered-end implants with an apical diameter of 4.1 mm and a neck diameter of 6.5 mm were placed in maxillary first or second molar sites, following manipulation of the remaining interradicular bone with osteotomes. Regenerative materials, consisting of demineralized freeze-dried bone allograft (DFDBA) and/or osseous coagulum, and bioabsorbable or non-resorbable membranes were placed, and passive soft-tissue primary closure was attained in all cases. RESULTS: Soft-tissue closure was maintained until the time of clinical reentry 6 months after implant insertion in 81 of 83 sites. Loss of primary soft-tissue closure in the other two areas did not result in complete uncovering of the cover screw and implant top. All implants were clinically immobile at the time of implant uncovery 6 months after insertion and were restored with single crowns. All implants were functioning successfully for up to 18 months (mean: 12.4 months). CONCLUSION: The combination of atraumatic removal of hopeless maxillary molars, controlled manipulation of the residual interradicular bone, insertion of implants of the aforementioned design, and use of appropriate regenerative materials at the time of implant insertion predictably afforded a stable implant for restoration with a single crown.