Vertical distraction osteogenesis in the human mandible: a prospective morphometric study

Vertical distraction osteogenesis has received considerable interest as a way to augment bone prior to implant placement. However, very little is known regarding the appropriate distraction protocols in the human mandible. In this study, we evaluate the effect of the distraction rate and the duration of neutrofixation on bone formation and closure of the gap in the human mandible. Vertical distraction was performed in the atrophic mandible of 16 edentulous patients, aged 62+/-6 years. The bone was distracted for approximately 10 mm at a rate of either 0.5 or 1 mm/day. Bone biopsies were taken after 7-20 weeks of neutrofixation. Histological analysis demonstrated newly formed bone in the distraction gap in all biopsies. The bone was predominantly of the woven type. After 10 weeks of neutrofixation, the gap was bridged by new bone in two out of three intact samples in the 0.5 mm/day group, but not in two intact samples of the 1 mm/day group. Histomorphometry revealed longer bone trabeculae (P=0.02) and a somewhat increased bone volume in the area where new bone formation started (P=0.07) in the group of patients having the 0.5 mm/day of distraction rate than in the 1 mm/day group. We conclude that in elderly patients, a distraction rate of 0.5 mm/day results in faster osteogenesis in the distraction gap than a rate of 1 mm/day. A minimum of 10 weeks of neutrofixation seems to be needed to close a 10 mm gap after cessation of distraction.     

Two-year clinical results following treatment of peri-implantitis lesions using a nanocrystalline hydroxyapatite or a natural bone mineral in combination with a collagen membrane

Objectives: The aim of the present case series was to evaluate the 2‐year results obtained following treatment of peri‐implantitis lesions using either a nanocrystalline hydroxyapatite (NHA) or a natural bone mineral in combination with a collagen membrane (NBM+CM). Material and Methods: Twenty‐two patients suffering from moderate peri‐implantitis (n=22 intra‐bony defects) were randomly treated with (i) access flap surgery (AFS) and the application of NHA, or with AFS and the application of NBM+CM. Clinical parameters were recorded at baseline and after 12, 18, and 24 months of non‐submerged healing. Results: Two patients from the NHA group were excluded from the study due to severe pus formation at 12 months. At 24 months, both groups revealed clinically important probing depth (PD) reductions (NHA: 1.5±0.6 mm; NBM+CM: 2.4±0.8 mm) and clinical attachment level (CAL) gains (NHA: 1.0±0.4 mm; NBM+CM: 2.0±0.8 mm). However, these clinical improvements seemed to be better in the NBM+CM group (difference between groups: PD reduction: 0.9±0.2 mm; CAL gain: 1.0±0.3 mm). Conclusion: Both treatment procedures have shown efficacy over a period of 24 months, however, the application of NBM+CM may result in an improved outcome of healing.     

Surgical regenerative treatment of peri-implantitis lesions using a nanocrystalline hydroxyapatite or a natural bone mineral in combination with a collagen membrane: a four-year clinical follow-up report

Objectives: The present case series aimed at investigating the 4-year clinical outcomes following surgical regenerative therapy of peri-implantitis lesions using either a nanocrystalline hydroxyapatite (NHA) or a natural bone mineral in combination with a collagen membrane (NBM+CM).
Materials and Methods: Twenty patients suffering from moderate peri-implantitis ( n =20 intrabony defects) were randomly treated with (1) access flap surgery (AFS) and the application of NHA ( n =9), or with AFS and the application of NBM+CM ( n =11). Clinical and radiographic (R) parameters were recorded at baseline (R) and after 36 and 48 (R) months of non-submerged healing.
Results: One patient from the NBM+CM group was discontinued from the study due to severe pus formation at 36 months. Compared with NHA, the application of NBM+CM resulted in higher mean PD reductions (NBM+CM: 2.5 ± 0.9 mm versus NHA: 1.1 ± 0.3 mm) and clinical attachment-level gains (NBM+CM: 2.0 ± 1.0 mm versus NHA: 0.6 ± 0.5 mm) at 48 months. A radiographic bone fill was observed for five sites in the NHA group, and eight sites in the NBM+CM group.
Conclusion: While the application of NBM+CM resulted in clinical improvements over a period of 4 years, the long-term outcome obtained with NHA without barrier membrane must be considered as poor.     

Immunohistochemical, tomographic and histological study on onlay bone graft remodeling. Part II: calvarial bone

Objectives: Little information is available on the molecular events that occur during graft incorporation over time. The calvarial bone (Cb) grafts have been reported to produce greater responses compared with other donor regions in maxillofacial reconstructions, but the scientific evidences for this are still lacking. The objectives of this study are (1) to study the morphological pattern of Cb onlay bone grafts and compare them with the biological events through immunohistochemical responses and (2) to establish the effects of perforations in maintaining the volume and bone density of the receptor bed. Material and methods: Sixty New Zealand White rabbits were submitted to Cb onlay bone grafts on the mandible. In 30 rabbits, the receptor bed was perforated (perforated group), while for the remaining animals the bed was kept intact (non‐perforated group). Six animals from each group were sacrificed at 5, 7, 10, 20 and 60 days after surgery. Histological sections from the grafted area were prepared for immunohistochemical and histological analyses. Immuno‐labeling was found for proteins Osteoprotegerin (OPG), receptor activator of nuclear factor‐κβ ligand (RANKL), alkaline phosphatase (ALP), osteopontin (OPN), vascular endothelial growth factor (VEGF), tartrate‐resistant acid phosphatase (TRAP), Type I collagen (COL I) and osteocalcin (OC). The tomography examination [computerized tomography (CT) scan] was conducted just after surgery and at the sacrifice. Results: The histological findings revealed that the perforations contributed to higher bone deposition during the initial stages at the graft–receptor bed interface, accelerating the graft incorporation process. The results of the CT scan showed lower resorption for the perforated group (P≤0.05), and both groups showed high bone density rates at 60 days. This set of evidences is corroborated by the immunohistochemical outcomes indicating that proteins associated with revascularization and osteogenesis (VEGF, OPN, TRAP and ALP) were found in higher levels in the perforated group. Conclusions: These findings indicate that the bone volume of calvarial grafts is better maintained when the receptor bed is perforated, probably resulting from more effective graft revascularization and greater bone deposition. The process of bone resorption peaked between 20 and 60 days post‐operatively in both groups although significantly less in the perforated group.     

Histomorphometric assessment of bone formation in sinus augmentation utilizing a combination of autogenous and hydroxyapatite/biphasic tricalcium phosphate graft materials: at 6 and 9 months in humans

Objective: The aim of this study was to examine the efficacy of a new biphasic hydroxyapatite/tricalcium phosphate (HA/TCP) bone substitute in combination with particulate autogenous bone in sinus floor augmentation procedures.
Material and methods: A simultaneous or a two-stage sinus augmentation and implant placement were conducted in 28 patients. A mixture of HA/TCP and autogenous bone chips in a 1 : 1 ratio was used as the grafting biomaterial. Cylindrical specimen bone retrieval was performed in all patients except one. Specimens were harvested either at 6 ( n =14) or 9 ( n =13) months post-augmentation. For histologic and histomorphometric evaluations, the non-decalcified tissue processing (Donath's technique) was performed.
Results: Newly formed bone around the grafted particles was found in all samples. The encircling, highly cellular bone followed the outline of the grafted particles in direct contact. Both woven and lamellar types of bone were observed.
Morphometrically, the total mean bone area fraction of all sections was 34.8±10.3%, increasing from 28.6±7.8% at 6 months to 41.6±8.3% at 9 months ( P <0.001). Mean particle area fraction average was 25.5±11.6% and 23.5±9.3% at 6 and 9 months, respectively, with a total mean of 24.5±10.4%. The increase in bone area fraction was not significantly correlated to the decrease of the grafted particles area fraction.
Conclusions: The biphasic HA/TCP showed biocompatible and osteoconductive properties. This alloplast as a composite with autogenous bone chips promotes newly formed bone, which increases in its fraction along an extended healing period.     

Effect of membranes and porous hydroxyapatite on healing in bone defects around titanium dental implants. An experimental study in monkeys.

The purpose of the present study was to examine the effect of treating bony craters around titanium dental implants with polytetrafluoroethylene membranes PTFE, with and without grafting of hydroxyapatite (HA), and with HA alone. 4 standardized bone defects were prepared in the alveolar ridge of edentulous areas in each of 7 monkeys. A titanium implant was then placed centrally in each defect, and in each monkey, the defects were treated with 1 of the following 4 treament modalities: 1 coverage with PTFE membrane;(2) grafting of HA and covering with a PTFE membrane;(3) HA grafting;(4) no treatment. Following a healing period of 12 weeks, all animals were sacrificed and mesiodistal ground sections of the treated areas were prepared. The histological analysis showed that all bone defects around the implants treated with PTFE membranes and 5 of the defects treated with HA and PTFE membranes were completely filled with new bone. The defects treated with HA alone and the control defects with no treatment only demonstrated new bone formation in the bottom of the defects. The results suggest that bone defects around titanium implants can be 1 treated successfully with PTFE membranes.     

Clinical evaluation of natural coral and porous hydroxyapatite implants in periodontal bone lesions: results of a 1 -year follow-up

Abstract This study examines the suitability of 2 bone graft substitutes, natural coral skeleton (NCS) and porous hydroxyapatite (PHA) for treating periodontal bone defects in human subjects, and compares them to debridement alone (DEBR). A total of 30 sites in 10 patients were treated. Measurements were made before treatment and during surgical reexamination 12 months after treatment on lesions filled with NCS (10 sites), PHA (10 sites), or DEBR (10 sites). There was no significant difference in the use of NCS or PHA for 1, 2 wall, or combined defects for the group of parameters measured in this study (clinical probing depth, clinical attachment, gingival recession, bone fill, % bone fill, and crest remodelling). Statistical analysis (Wilcoxon non-parametric test for paired values and ANOVA for repeated measurements) revealed the beneficial effects of using each the biomaterials (57.4% for NCS, 58.1% for PHA, p < 0.86) as opposed to simple debridement (22.2%; p < 0.002; p < 0.004).     

rhBMP-2、PRF和自体骨分别复合珊瑚羟基磷灰石成骨效能的比较研究

目的：通过建立动物骨缺损模型,比较重组人骨形成蛋白-2（rhBMP-2）与珊瑚羟基磷灰石（CHA）复合物、富血小板纤维蛋白（PRF）与珊瑚羟基磷灰石复合物、自体骨与珊瑚羟基磷灰石复合物以及单纯珊瑚羟基磷灰石这四种骨移植材料在骨缺损中的成骨效能。方法：在比格犬双侧胫骨干骺端制备四个相同的骨缺损区,在缺损区分别植入rhBMP-2/CHA、 PRF/CHA、自体骨/CHA及CHA （对照）;3个月后处死动物,行大体标本观察;拍牙科CT,观察各植骨区骨密度情况;制作石蜡切片、 HE染色,比较各植骨区骨组织学特点及新骨形成量。结果：大体标本见四组骨缺损间隙均完全关闭。 X线示自体骨/CHA组和PRF/CHA组骨密度较致密, rhBMP-2/CHA组致密性低于前两者, CHA组未见明显骨致密影。 HE切片见四组新生骨与宿主骨连接紧密,新生骨小梁不规则,粗细不一,排列无序;复合型骨移植材料的新生骨小梁比对照组更密集、粗大,连续性更好;四组植骨区成骨量比较：自体骨/CHA组〉PRF/CHA组〉rhBMP-2/CHA组〉CHA组。结论：复合型骨移植材料成骨效应明显优于单纯珊瑚羟基磷灰石;三种复合型材料中自体骨/CHA成骨效应最好,其次为PRF/CHA, rhBMP-2/CHA最差。     

Autogenous onlay bone grafts vs. alveolar distraction osteogenesis for the correction of vertically deficient edentulous ridges: a 2-4-year prospective study on humans

OBJECTIVES: The purposes of this study were to compare: (a) autogenous bone grafts (ABG) and distraction osteogenesis (DO) for their ability in correcting vertically deficient mandibular ridges and their capability in maintaining over time the vertical bone gain obtained before and after implant placement; and (b) the survival and success rates of implants placed in the reconstructed or distracted areas. MATERIAL AND METHODS: In a 2-year period (2001-2002), 17 patients presenting with vertically atrophied partially edentulous mandibles requiring implant-supported prosthetic rehabilitation, were included in this study. Patients were randomly assigned to two groups. Eight patients (group 1) were treated with ABG harvested from the mandibular ramus, while nine patients (group 2) were treated by means of DO. In group 1, patients received implants 4-5 months after the reconstructive procedure, while in group 2 implants were placed at the time of distraction device removal (approximately 3 months after the completion of distraction). A total of 19 endosseous implants were placed in group 1, and 21 implants were placed in group 2 patients. For both groups, after an additional 3-5-month period, prosthetic rehabilitation was started. RESULTS: Bone resorption before implant placement was significantly higher in group 1 (P=0.01), while no statistically significant differences were found between the two groups as far as survival and success rates of implants and peri-implant bone resorption after the start of prosthetic loading were concerned. CONCLUSION: The results suggested that: (a) both techniques may effectively improve the deficit of vertically resorbed edentulous ridges; (b) survival and success rates of implants placed in the reconstructed/distracted areas are consistent with those of implants placed in native bone.     

Y500R可吸收珊瑚羟基磷灰石人工骨体外成骨细胞相容性研究

目的：探讨Y500R可吸收珊瑚羟基磷灰石作为人工骨支架材料在体外的成骨效能,评价其组织相容性的优劣,为临床应用提供必要的实验依据。方法：采用酶消化法获得小鼠成骨细胞后,分为空白组、实验组和对照组。空白组为小鼠成骨细胞单独培养,实验组和对照组分别为颗粒型Y500R可吸收珊瑚羟基磷灰石、颗粒型羟基磷灰石（HA）与小鼠成骨细胞复合培养。对比小鼠成骨细胞在3组中的生长状况、形态学特征、碱性磷酸酶活性、矿化结节形成等成骨活性指标的差异,并采用扫描电镜观察、对比Y500R人工骨与角孔珊瑚在支架三维结构、孔隙率、孔径及孔的均匀度方面的差异。结果：实验组成骨细胞在成骨活性等指标方面与空白组无显著性差异。扫描电镜下可见Y500R可吸收珊瑚羟基磷灰石的断面呈多孔海绵状结构,微孔呈圆形,排列规则,与天然松质骨结构十分相似。Y500R的三维多孔结构和孔隙率与角孔珊瑚相比,结构类似,在电镜下几乎分不出差异,唯孔径比角孔珊瑚略小,但大小均匀、规则。结论：Y500R可吸收珊瑚羟基磷灰石具有良好的细胞相容性和成骨活性,复合培养不影响成骨细胞的正常生理功能,Y500R可吸收珊瑚羟基磷灰石能够满足组织工程对支架材料的要求,可作为一种新型的骨代用品。     

Bone response to free form-fabricated hydroxyapatite and zirconia scaffolds: a histological study in the human maxilla

Objectives: Synthetic and biological materials are increasingly used to provide temporary or permanent scaffolds for bone regeneration. This study evaluated the effect of material chemistry and microporosity on bone ingrowth and osseointegration of zirconia (ZrO₂) and hydroxyapatite (HA) scaffolds in the human maxilla.
Material and methods: Twelve patients subjected to dental implant placement were enrolled in the study. Scaffolds of ZrO₂ and HA were placed in the maxilla of each subject, using a randomization protocol. After 3 months of healing, biopsies were harvested comprising the scaffolds and surrounding bone tissue. The biopsies were processed for histological evaluation and morphometric analysis (bone ingrowth and bone-to-scaffold contact).
Results: Healing was uneventful in all cases. All scaffolds demonstrated a measurable bone response using light microscopy and scanning electron microscopy. Microporous HA scaffolds revealed four times larger bone ingrowth and seven times larger bone contact as compared with ZrO₂ scaffolds.
Conclusion: The results show that chemistry and microporosity of HA promote bone ingrowth and bone contact of ceramic scaffolds in human maxilla.     

Healing of intrabony peri-implantitis defects following application of a nanocrystalline hydroxyapatite (Ostim) or a bovine-derived xenograft (Bio-Oss) in combination with a collagen membrane (Bio-Gide). A case series

OBJECTIVES: The aim of the present case series was to evaluate the healing of intrabony peri-implantitis defects following application of a nanocrystalline hydroxyapatite (NHA) or a bovine-derived xenograft in combination with a collagen membrane (BDX+BG). MATERIAL AND METHODS: Twenty-two patients having moderate peri-implantitis (n=22 intrabony defects) were randomly treated with (i) access flap surgery (AFS) and the application of NHA, or with AFS and the application of BDX+BG. Clinical parameters were recorded at baseline and after 6 months of non-submerged healing. RESULTS: Post-operative wound healing revealed that NHA compromized initial adhesion of the mucoperiosteal flaps in all patients. At 6 months after therapy, NHA showed a reduction in the mean PD from 7.0+/-0.6 to 4.9+/-0.6 mm and a change in the mean clinical attachment loss (CAL) from 7.5+/-0.8 to 5.7+/-1.0 mm. In the BDX+BC group, the mean PD was reduced from 7.1+/-0.8 to 4.5+/-0.7 mm and the mean CAL changed from 7.5+/-1.0 to 5.2+/-0.8 mm. CONCLUSION: Within the limits of the present case series, it can be concluded that at 6 months after surgery both therapies resulted in clinically important PD reductions and CAL gains.     

Vertical distraction osteogenesis of the mandible applied to an iliac crest graft: report of a case

OBJECTIVES: This clinical case represents a particular application of vertical distraction osteogenesis of the mandible. The surgical technique was applied to an iliac crest bone graft previously positioned on an anterior mandibular defect with the aim to restore the vertical height after a partial resorption in a trauma patient. CASE REPORT: Distraction osteogenesis was applied because it was necessary to restore the mandibular height in a young male patient who presented with a post-trauma anterior mandibular bony deficiency. Because of the irregularity of the mandibular surface and the depth of the defect, the patient first underwent an iliac crest bone grafting that, after 3 months, showed partial resorption. Vertical distraction osteogenesis was performed on the grafted mandible in order to obtain a satisfactory bony height of the mandibular ridge. Then the patient was successfully rehabilitated by means of an implant-supported prosthesis. CONCLUSION: Vertical distraction osteogenesis appears to be a versatile surgical procedure, which can be applied as a secondary treatment in patients presenting with mandibular trauma sequelae.