Clinical and histologic evaluation of the demineralized freeze-dried bone membrane used for ridge augmentation

The biologic principle of guided bone regeneration has been successfully used to regenerate alveolar ridges. The objective of this pilot study was to clinically and histologically evaluate the demineralized freeze-dried bone membrane. Four premolar teeth were extracted from two dogs, and the remaining alveolar bone was surgically reduced in width and height to produce Class III ridge defects. After a 2-month healing period, mucoperiosteal flaps were elevated, and demineralized freeze-dried cortical columns were used as space maintainers. Bone membranes were used as barriers. The animals were sacrificed at 3 months and the surgical areas were recovered and processed for histologic evaluation. Results showed ridge augmentation in all sites. Clinically, the augmented areas appeared to have the same hardness as the surrounding bone on the periphery of the experimental site. After elevation of a mucoperiosteal flap, the bone membrane could be seen. Histologically, the bone membrane acted as an efficient barrier, excluding the nonosteogenic tissues. New bone formation underneath the membrane was found in all specimens. This study suggests that a bone membrane in combination with a space maintainer can guide new bone formation to regenerate localized chronic alveolar ridge defects.     

Alveolar ridge augmentation using nonresorbable hydroxylapatite with or without autogenous cancellous bone

A four-year prospective evaluation of the use of nonresorbable, particulate hydroxylapatite (HA) to augment deficient alveolar ridges was performed. The material was used alone and in combination with finely crushed autogenous cancellous bone. Implants were delivered subperiosteally by syringe injection, usually using local anesthesia for Class I to Class III ridges and general anesthesia for Class III and Class IV ridges. The improved ridge height and width were stable. Postoperative resorption with significant loss of ridge height, frequently seen with rib and iliac crest onlayed grafts, was not observed with HA augmentation. Permanent denture construction began as early as three weeks postoperatively and by four to six weeks if HA was combined with autogenous cancellous bone. It was possible to place mandibular staple implants simultaneously or following HA augmentation. Visor osteotomy techniques were improved by use of HA to produce a wider, more convex stable ridge. Although skin, mucosa, or dermal vestibuloplasties were performed as early as three months postoperatively in a small number of patients, there appeared to be a lesser need for vestibuloplasty after HA augmentation than after onlay bone grafting. In addition, prosthodontists performed fewer denture relines after HA augmentation than after onlay bone grafts. The authors believe the most significant factor accounting for these observations is the firm, nonmobile mucosal base resulting from augmentation with HA. The resultant stable, soft tissue base and improved ridge height and contour have contributed to a comfortable, retentive, stable denture for these patients. The prosthetic and surgical procedures are easier to perform and have produced superior, more permanent results than onlay bone grafts and alloplasts. Preliminary studies also point to exciting possibilities for use of HA as a bone substitute/marrow extender in maxillary and mandibular defects, cysts, and clefts and in osteotomies for orthognathic surgery.     

Healing of mandibular ridge augmentations using hydroxylapatite with and without autogenous bone in dogs

Dog mandibles were augmented with either hydroxylapatite (HA) alone or HA combined with autogenous bone. Within the limited time frame of this experiment (16 weeks) the group which received HA alone did not demonstrate the induction of bony ingrowth further than 1-2 mm into the augmented ridge. However, the animals augmented with HA combined with autogenous bone demonstrated an active, lamellar-type bony ingrowth, maturing bony haversian systems, and vascular elements forming throughout the entire area, extending to the overlying soft tissue interface. The clinical assessment of both types of augmented ridges (HA and HA and bone) were similar; both formed hard, firm ridges at approximately the same rate. This observation is consistent with human clinical experience with HA or HA mixed with bone. However,for patients who have severe mandibular atrophy and for whom increased mandibular bony bulk is crucial, a combination of HA and bone should be advantageous because of the increased extent of bony ingrowth.     

Loaded hydroxylapatite-coated implants and uncoated titanium-threaded implants in distracted dog alveolar ridges

AIMS: The aim of this study was to determine the response of alveolar bone after it was augmented vertically with distraction osteogenesis, implanted with hydroxylapatite (HA)-coated implants and noncoated titanium-threaded implants, and subsequently loaded for 1 year. METHODS: Eight dogs each had 4 implants placed horizontally into an edentulous mandibular quadrant. After integration, a distraction osteogenesis device was fabricated in the laboratory. An osteotomy was made to allow the crest of the alveolar ridge to be distracted vertically. After 10 mm of vertical distraction, the distraction devices were stabilized with light cured resin. After bone fill of the distraction gap was radiographically confirmed in all dogs at 10 weeks, 2 implants were placed into the ridges. Four dogs had threaded titanium implants placed, and 4 dogs had threaded HA-coated implants placed, with 1 implant in the distracted bone and 1 implant in adjacent nondistracted bone, for both groups. After 4 months for implant integration, bridges were fabricated and secured to the implants with screws. Crestal bone levels were evaluated by radiographs through 1 year of function. Animals were killed after 1 year of loading for histologic evaluation. RESULTS: The vertical ridge augmentation averaged 8.8 +/- 1.0 mm after 10 weeks of healing after distraction. Analysis of variance indicated a significantly greater change from baseline for HA-coated implants and for distracted bone sites. Histologic examination showed that bone had formed between the distracted segments creating an augmented ridge. The average thickness of the labial cortex in the distraction gap was significantly thinner than the lingual cortex in distracted bone or the lingual and labial nondistracted cortical bone. The presence of a dental implant did not significantly affect cortical bone thickness. Serial sections showed that implants remained integrated and functional without soft tissue inflammation. CONCLUSION: Dental implants placed into alveolar ridges augmented with the technique of distraction osteogenesis were functional for the length of this study.     

空气喷磨机去除窝沟龋的扫描电镜观察

使用美国空气喷磨机（ＫＣＰ１０００），选用２７μｍ颗粒，８．２６８×１０＾５Ｐａ（１２０ｐｓｉ）气压，喷磨时间５～１０ｓ作为实验参数喷除新鲜离体人牙Ｈｅ面窝沟龋，扫描电镜观察显示，ＫＣＰ去龋干净，形成的釉质窝洞线角及洞缘圆钝，洞底粗糙不平，呈密集，不规则的凹凸状结构，实验结果提示ＫＣＰ能有效去除窝沟龋，产生的形态学改变特别适合应用复合树脂的粘接。     

Ridge augmentation using solid and porous hydroxylapatite particles with and without autogenous bone or plaster

Edentulous areas of dog jaws were augmented with solid or porous particles of hydroxylapatite (HA) alone, or combined with either finely crushed autogenous bone or plaster of paris. At the end of the experiment (24 weeks), the augmented ridges were firm and stable and covered with healthy mucosa. The ridges augmented with only porous particles of HA demonstrated a greater amount of bone ingrowth compared with the solid, dense particles. The new bone formation occurred in those parts of the implants adjacent to the underlying alveolar bone. The addition of autogenous bone to the HA particles did not enhance bony deposition, and none of the autogenous bone chips survived for 24 weeks. The amount of new bone in the ridges augmented with plaster of paris and HA was similar to the other groups, and the plaster did not interfere with healing. There was evidence of resorption of the underlying cortical bone in many of the specimens.     

Effect of recombinant human bone morphogenetic protein-2 in an absorbable collagen sponge with space-providing biomaterials on the augmentation of chronic alveolar ridge defects

BACKGROUND: Recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) carrier has been shown to support significant bone formation in the craniofacial skeleton. When used as an onlay, however, rhBMP-2/ACS may become compressed with limited resulting bone formation. The objective of this study was to evaluate the effect of two space-providing biomaterials, bioactive glass (BG) and demineralized/mineralized bone matrix (DMB), on rhBMP-2/ACS induced alveolar ridge augmentation. METHODS: Bilateral alveolar ridge defects were produced in the mandible in six mongrel dogs. rhBMP-2/ACS with biomaterials was surgically implanted into contralateral defects in four animals. Treatments were alternated between jaw quadrants in consecutive animals. Two animals received rhBMP-2/ACS or sham-surgery in contralateral defects. The animals were injected with fluorescent bone labels to monitor bone formation. Clinical evaluations were made at ridge augmentation and 12 weeks post-implantation when the animals were euthanized and block biopsies collected for histopathologic evaluation. RESULTS: Sham-surgery produced limited horizontal alveolar augmentation (0.1 +/- 0.6 mm). Implantation of rhBMP-2/ACS resulted in alveolar augmentation amounting to 2.2 +/- 1.8 mm. Alveolar augmentation in sites receiving rhBMP-2/ACS with DMB or BG was 2-fold greater compared to rhBMP-2/ACS alone averaging 4.4 +/- 1.3 and 4.6 +/- 1.5 mm, respectively. The DMB biomaterial appeared substituted by newly formed bone. The BG particles were observed imbedded in bone or encapsulated in dense connective tissue without associated bone metabolic activity. Fluorescent light microscopy suggested that the new bone was formed within 4 weeks. CONCLUSION: The bioglass and demineralized/mineralized bone matrix biomaterials utilized in this study in combination with rhBMP-2/ACS supported clinical and histological ridge augmentation.     

Alveolar ridge augmentation with rhBMP-2 and bone-to-implant contact in induced bone.

The objective of this study was to examine alveolar ridge augmentation following implantation of recombinant human bone morphogenetic protein (rhBMP-2) with an allogeneic freeze-dried demineralized bone matrix (DBM) mixed with autologous blood. A second objective was to evaluate bone-to-implant contact in induced bone. Bilateral surgically created supraalveolar ridge defects in five young adult beagle dogs were implanted with the rhBMP-2-DBM-blood device. Transmucosal dental implants were placed at weeks 8 and 16 postsurgery The animals were euthanized 24 weeks following ridge augmentation. Healing was uneventful in all animals. Radiographic observations indicated substantial bone formation, including regions of radiolucency, at week 8. At week 16, the radiolucencies were generally resolved, and the trabecular structure of the induced bone resembled that of the adjacent residual bone. There were no remarkable differences in radiographic observations between weeks 16 and 24 after ridge augmentation. Histologic analysis revealed dense woven and lamellar induced bone. Any residual DBM appeared remineralized, at least in part. A large portion of the dental implants (approximately 70%) were housed in induced bone with evidence of limited crestal resorption. There was no significant difference in bone density between induced and residual bone, and the levels of bone-to-implant contact were similar (approximately 55%). The rhBMP-2 construct used in this study has a potential to augment alveolar ridge defects. Also, no difference in levels of osseointegration may be expected in induced and residual bone following a two-stage procedure of rhBMP-2-induced ridge augmentation and dental implant placement.     

Use of durapatite for the rehabilitation of resorbed alveolar ridges

These investigations were undertaken to evaluate durapatite, a particulate, ceramic, nonresorbable bone-grafting material for augmentation of deficient alveolar ridges. A total of 207 augmentations were reported among 198 patients over 24 months. Subjective and objective data showed that durapatite alone was successful for all classes of ridges augmented; height, bulk, contour, and ridge form generally improved and soft tissue overlying the augmented ridges was firm and immobile. Impressions for dentures usually began 4 to 6 weeks after surgery and these dentures remained stable, retentive, and esthetically pleasing throughout the study. Other than transiently altered sensations resulting from mental nerve manipulation during surgery, no other important procedural complications were noted. No infection or bone resorption beneath the implant was observed throughout these studies. Durapatite used in an outpatient setting provides a less costly and more permanent method for alveolar ridge augmentation than do augmentation procedures using autogenous or banked bone.     

The effect of therapeutic radiation on canine alveolar ridges augmented with hydroxylapatite.

The purpose of this investigation was to evaluate the effect of radiation on hydroxylapatite (HA) implanted subperiosteally for alveolar ridge augmentation in dogs. All bicuspids and molars were extracted from 16 dogs. After 6 weeks, nonporous HA granules were implanted subperiosteally on the alveolar ridge. Following 4 months of healing, 12 dogs (experimental group) underwent therapeutic radiation therapy (Co60, 4,000 rad [40 Gy]) to the head and neck region. Four dogs were not irradiated and served as controls. Four animals (three experimental and one control) were killed at 5,6,7, and 8 months after HA augmentation. Light microscopic evaluation showed that approximately 25% of HA granules were encased by bone while the others were surrounded by fibrous connective tissue. Dissolution of the HA was observed. Microparticles of HA were phagocytized as part of a granulomatous inflammatory reaction. This reaction decreased significantly as time elapsed after implantation. Osteoclastic activity was seen at the junction of HA and periosteum and as part of bone remodeling. Dissolution of the HA granules and the granulomatous inflammatory reaction were not significantly increased by therapeutic radiation. The radiation did not cause development of dehiscence or osteonecrosis.     

Alveolar ridge augmentation in rats by combined hydroxylapatite and osteoinductive material.

The purpose of this study was to examine if increased bony ingrowth developed when hydroxylapatite was implanted together with an osteoinductive substrate. Dense hydroxylapatite granules (HA) (Calcitite, Calcitek, San Diego, CA, USA) were mixed with equal volumes of allogenic, demineralized, lyophilized dentin or bone and implanted subperiosteally for alveolar ridge augmentation purposes and heterotopically in the abdominal muscles in rats. Light microscopic evaluation revealed that HA was surrounded by fibrous connective tissue containing foreign body giant cells and it had neither an osteoinductive nor an osteoconductive effect. The newly formed bone induced from the implanted allogenic, demineralized, lyophilized dentin or bone was never found in close contact with the HA and did not incorporate the implant.     

Alveolar ridge augmentation in rats by combined hydroxylapatite and osteoinductive material

Abstract— The purpose of this study was to examine if increased bony ingrowth developed when hydroxylapatite was implanted together with an osteoinductive substrate. Dense hydroxylapatite granules (HA) (Calcitite, Calcitek, San Diego, CA, USA) were mixed with equal volumes of allogenic, demineralized, lyophilized dentin or bone and implanted subperiosteally for alveolar ridge augmentation purposes and heterotopically in the abdominal muscles in rats. Light microscopic evaluation revealed that HA was surrounded by fibrous connective tissue containing foreign body giant cells and it had neither an osteoinductive nor an osteoconductive effect. The newly formed bone induced from the implanted allogenic, demineralized, lyophilized dentin or bone was never found in close contact with the HA and did not incorporate the implant.     

Nonporous hydroxylapatite granules as an extracranial and extranasal augmenting material in dogs: technique and initial findings

The purpose of this study was to evaluate the use of nonporous hydroxylapatite (HA) granules as an extracranial and extranasal augmentation material in dogs. Clinical evaluation revealed that the HA granules became stable within 6 weeks and lost some of the augmented height. Histologic evaluation revealed no evidence of inflammation, bone resorption, or bone formation; also the granules were separated from other granules and the cranial surface by a layer of collagen fibers. This study concluded that nonporous HA granules are a practical extracranial and extranasal augmentation material, but its final augmentation contour is difficult to predict and control because of the consistency of the material. Either researchers need to develop a better method to stabilize HA granules in extracranial and extranasal applications or they need access to an HA block material that maintains better augmented contour.     

Alveolar ridge augmentation using titanium micromesh: an experimental study in dogs.

PURPOSE: Augmentation of the alveolar ridge before implant placement is frequently performed. The purpose of this study was to compare the amount and quality of bone formation under Micro Titanium Augmentation Mesh (M-TAM) when used alone for guided tissue regeneration or in combination with a porous hydroxyapatite (HA) bone graft substitute. MATERIALS AND METHODS: Nine adult female dogs underwent extraction of premolars and molars and had a knife-edge ridge created. Three months later, the ridges were augmented with either M-TAM alone or M-TAM with a nonresorbable porous HA (Interpore 200; Interpore Cross International, Irvine, CA). Six months after augmentation, the dogs were killed, and the mandibles were harvested and imaged using 3-dimensional computed axial tomography. Statistical analysis was performed from the data obtained from the scans. The mandibles were then fixed, sectioned, and examined by light microscopy. RESULTS: Dehiscence occurred in 22 of 32 experimental sites. Seven of these 22 dehisced sites showed increased ridge width. Ridge width increased in both the HA and non-HA groups. The HA group showed a greater increase in ridge width. CONCLUSION: A high rate of dehiscence was observed in this animal study using M-TAM for guided tissue regeneration. In animals that did not dehisce, increased width was greater when nonresorbable porous HA was used as a bone graft substitute.     

Alveolar ridge augmentation with bioactive glass ceramics: a histological study

A particulate BGC (bioactive glass ceramics), has been developed as a new bone graft biomaterial for alveolar ridge augmentation and has been evaluated by simulated animal models. Five beagle dogs were used in this investigation. Prior to augmentation the mandibular posterior teeth of the animals were extracted. Three months after the extractions, the porous BGC particles were packed into the subperiosteal tunnels in the ridges with a special syringe. The animals were killed at different time intervals and the specimens were examined by light microscopy, scanning electron microscopy (SEM), and X-ray energy dispersive analysis (EDAX), respectively. The results of this study indicate that the BGC particles are firmly combined with the adjacent hard and soft tissues by the bone bonding interface between the implants and the alveolar bone, and by the ingrowth of bone or fibrous connective tissue into the interspaces and the pores of the particles. The results have demonstrated that particulate BGC with pores is an excellent implant material for alveolar ridge augmentation because of its very good biocompatibility.     

Localized vertical maxillary ridge augmentation using symphyseal bone cores: a technique and case report

Vertical augmentation of the alveolar ridge is intended to restore resorbed alveolar ridges. This procedure is important for the placement of dental implants in a favorable position and also to enhance restoration esthetics. This article presents an approach for vertical ridge augmentation in the anterior maxilla utilizing symphyseal bone cores. A patient presented with 2 localized bony defects around the maxillary lateral incisors. Following extraction of these teeth, vertical bone defects of 7 mm on the right and 6 mm on the left were observed in relation to the cementoenamel junction of the adjacent teeth. Two bone cores were harvested from the mandibular symphysis using a trephine. These bone cores were tapped into 2 predrilled osteotomy sites with corresponding diameters until stabilization was achieved. The 2 sites were grafted with demineralized freeze-dried bone allograft and a titanium-reinforced expanded polytetrafluoroethylene membrane. After 5 months, the membranes were removed and vertical ridge augmentation of 5 mm on the right and 4 mm on the left was observed. The width of the ridge was increased as well. Two implants were placed in favorable positions, restored after 6 months, and followed successfully for 1 year after loading. This technique represents a viable approach for augmentation of deficient alveolar ridges prior to the placement of dental implants.     

羟基磷灰石复合骨诱导蛋白“夹心”式植入牙槽嵴加高术

为解决粘膜裂开、溃疡形成及术后变形等问题，采用羟基磷灰石（ｈｙｄｒｏｘｙａｐａｔｉｔｅ，ＨＡ）复合骨诱导蛋白（ｂｏｎｅｍｏｒｐｈｏｇｅｎｉｃｐｒｏｔｅｉｎ，ＢＭＰ）“夹心”式植入修复牙槽嵴萎缩。动物实验术后行光镜和扫描电镜观察，临床病例术前术后进行Ｘ光片检查。结果显示：实验动物术后植入物牢固，周围有大量新骨形成且多面与宿主骨连接。由于牙槽嵴顶部外形、解剖结构完好，临床检查见修复效果可靠，并发症较少，术后义齿修复满意。结果表明：采用ＨＡ－ＢＭＰ复合物“夹心”式植入修复牙槽嵴萎缩有如下优点：①利用ＨＡ与ＢＭＰ共同作用，生物相容性好，具备骨引导和骨诱导双重功能，新骨形成快而多；②植入物与原牙槽嵴多面结触，诱导新骨形成作用强，植入物固位好，术后牙槽嵴不易变形，增加高度大、可靠；③保持了牙槽嵴顶的原解剖结构，不易形成粘膜破裂及溃疡；④形成的新骨与原宿主骨为直接连结，强度大；⑤手术简捷、安全。     

Augmentation of rat mandibular ridge with demineralized bone implants

Demineralized bone implants were placed as onlays in submucosal pockets on the edentulous segment of the rat mandible, between the incisor and posterior teeth. These implants, predictably, induced osteogenesis. The mass of induced bone and implant was united to the ridge by two weeks, and there was little or no resorption over a six-month follow-up period. This study suggests that demineralized bone implants may be useful for mandibular ridge augmentation.     

Experimental alveolar ridge augmentation by distraction osteogenesis using a simple device that permits secondary implant placement

The purpose of this study was to develop an improved technique of alveolar ridge augmentation by distraction osteogenesis using distraction screws, and to investigate tissue reactions to titanium implants at the distraction site. The left mandibular premolars were extracted from 6 adult dogs. After 12 weeks, a box-shaped osteotomy of the alveolar bone was carried out, and distraction devices were placed on the transport and base segments. After a 7-day latency period, the alveolar bone was augmented by 7 mm vertically at a rate of 1.0 mm/day. Just after distraction, these devices were replaced with dental implants for fixation of the transport segment and bone formation of the distraction site. Histologic and radiographic evaluations were made at 8 and 12 weeks after distraction. Vertical augmentation averaged 6.1 mm after 12 weeks of consolidation. It was possible to lengthen the alveolar bone without great difficulty, and good bone formation was recognized in the distraction site. Greater integration between the implant and the distracted bone was observed at 12 weeks after distraction than at 8 weeks. Distraction osteogenesis was successfully applied to alveolar ridge augmentation by this improved technique, and the implants osseointegrated in the augmented ridge.     

Use of hydroxylapatite for the augmentation of deficient alveolar ridges

Investigations were undertaken to evaluate nonresorbable, particulate ceramic hydroxylapatite (durapatite) for augmentation of deficient alveolar ridges. One hundred and fifteen augmentations in both jaws were reported for 110 patients over a 33-month postoperative period. Subjective and objective data show that the implant was successful for all classes of ridges augmented; height, bulk, contour, and ridge form generally improved, and soft tissue overlying the augmented ridges was firm and immobile. Impressions for dentures were usually obtained four to six weeks after surgery, and the dentures were more stable, retentive, and esthetically pleasing than the preoperative prostheses and required fewer relinings. Other than transiently altered sensations resulting from mental nerve manipulation during surgery, patients had few complications. No infection or bone resorption beneath the implant was observed throughout these studies. It was concluded that hydroxylapatite particles placed through a subperiosteal tunnel offer a highly successful method of ridge augmentation and eliminate the most serious problems associated with the use of autogenous or banked bone, namely, morbidity, risk, costliness, and poor results.