Measurement of ridge alterations following tooth removal: a radiographic study in humans

Objective: The aim of this study was a radiographic mesiodistal analysis of the shape of the bone crest 3 months after tooth removal. Material and methods: One hundred single tooth extractions were performed on 100 patients because of orthodontic or prosthetic causes. Bite blocks were used for two radiographs: one on the day of extraction and the other after healing of the socket, 3 months later. These X‐rays were used to determine: (1) the most apical distance of alveolar ridge resorption, with baseline as the line between bone‐to‐teeth contact (the greatest distance in bone resorption height) and (2) the mesiodistal distance (MDD) and mesial and distal angles arising after bone tissue modeling. Results: Significant differences (P<0.05) emerged between the MDDs of multiple‐ [8 mm, 95% confidence interval (CI): 6.09, 9.90] and single‐root teeth (5.60 mm, 95% CI: 4.80, 6.50). However, mesial or distal angles or the most apical distance of alveolar ridge resorption did not differ (mean distance in height=4.32 mm, 95% CI: 3.85, 4.78; mean angle=24°). Conclusions: In this study, the post‐extraction mesiodistal bone distance between teeth adjacent to the edentulous ridge depends on the size of the edentulous space. Nevertheless, the distance does not affect the distance in bone loss height. The distance of bone resorption height reaches a balance at the midpoint, which we consider indicative of stable healing. This resorption process must be considered when placing dental implants in fresh extraction sockets, especially in aesthetic sites, because the implant surfaces could be exposed after 3 months. To cite this article:
Moya‐Villaescusa MJ, Sánchez‐Pérez A. Measurement of ridge alterations following tooth removal: a radiographic study in humans.
Clin. Oral Impl. Res. 21 , 2010; 237–242.
doi: 10.1111/j.1600‐0501.2009.01831.x     

Dynamics of bone tissue formation in tooth extraction sites. An experimental study in dogs

OBJECTIVES: The aim of the present experiment was to study events involved in the healing of marginal, central and apical compartments of an extraction socket, from the formation of a blood clot, to bone tissue formation and remodeling of the newly formed hard tissue. MATERIAL AND METHODS: Nine mongrel dogs were used for the experiment. The fourth mandibular premolars were selected for study and were divided into one mesial and one distal portion. The distal root was removed and the socket with surrounding soft and mineralized tissue was denoted "experimental unit". The dogs were killed 1, 3, 7, 14, 30, 60, 90, 120 and 180 days after the root extractions. Biopsies including the experimental units were demineralized in EDTA, dehydrated in ethanol and embedded in paraffin. Serial sections 7 microm thick were cut in a mesio-distal plane. From each biopsy, three sections representing the central part of the socket were selected for histological examination. Morphometric measurements were performed to determine the volume occupied by different types of tissues in the marginal, central and apical compartments of the extraction socket at different intervals. RESULTS: During the first 3 days of healing, a blood clot was found to occupy most of the extraction site. After seven days this clot was in part replaced with a provisional matrix (PCT). On day 14, the tissue of the socket was comprised of PM and woven bone. On day 30, mineralized bone occupied 88% of the socket volume. This tissue had decreased to 15% on day 180. The portion occupied by bone marrow (BM) in the day 60 specimens was about 75%, but had increased to 85% on day 180. CONCLUSION: The healing of an extraction socket involved a series of events including the formation of a coagulum that was replaced by (i) a provisional connective tissue matrix, (ii) woven bone, and (iii) lamellar bone and BM. During the healing process a hard tissue bridge--cortical bone--formed, which "closed" the socket.     

Effect of calcitonin on alveolar wound healing

The effect of calcitonin (CT) on alveolar wound healing was studied with histomorphometric methods. Wistar rats weighing 80-90 g were submitted to extraction of the three mandibular molars. Half of them were injected intraperitoneally with daily therapeutic doses of CT. The control group received no further treatment. All the rats were killed 14 days after the onset of the experiment. Bone healing was impaired in CT treated animals and involved a more intense bone remodeling activity. Bone resorptive areas were present both on the profiles of the newly formed bone and on the alveolar ridge surface. These results suggest that CT would accelerate the process of bone healing.     

Comparative study of the osseous healing process following three different techniques of bone augmentation in the mandible: an experimental study

The aim of this study was to evaluate the osseointegration of three different bone grafting techniques. Forty-eight mature New Zealand rabbits were divided randomly into three groups of 16 each. Horizontal augmentation was performed on the corpus of the mandible using three different techniques: free bone graft (FBG), free periosteal bone graft (PBG), pedicled bone flap (BF). The animals were sacrificed at postoperative weeks 1, 3, or 8. Specimens were decalcified for histological examination, and histomorphometric measurements were performed. The histological evaluation demonstrated bony fusion between the grafts and the augmented mandibular bone after 8 weeks in all groups. At week 8, the bone volume was significantly greater in the BF group than in the FBG (P < 0.001) and PBG (P = 0.001) groups, and also the trabecular thickness was significantly greater than in the FBG (P = 0.015) and PBG (P = 0.015) groups. Trabecular separation was significantly lower in the BF group than in the FBG group at week 8 (P = 0.015). BF demonstrated greater osseous healing capacity compared to FBG and PBG. The preserved vascularization in BF improves the bone quality in mandibular bone augmentations.     

Surgical intervention in enchondral and membranous bone: intraindividual comparisons in the rabbit

Background: The long bones, which are of enchondral origin, are often used in histologic evaluations of dental implants that clinically will be placed in bones of membranous origin. Purpose: The aim of this investigation was to study the effect of surgical trauma by multiple drill perforations on both enchondral and membranous bone—the tibial and maxillary bone architecture—8 weeks after surgery. Materials and Methods: In eight rabbits the medial metaphyses of both tibiae and the edentulous ridges of both sides in the maxilla were surgically exposed. On the test sides, 25 to 30 holes were drilled through the cortical plate and 5 mm into the medullary space. The contralateral sides underwent no treatment and served as controls. Eight weeks later the animals were killed to obtain transverse ground sections for histomorphometry. A paired analysis of the bone densities of the tibiae and the jaw specimens was made. Results: In general the morphologic appearances of the test and control tibiae were similar. In the control group the anatomy of the medullary space appeared normal, with few bone trabeculae and with abundant marrow tissue. In the test group, areas of resorption were evident on the cortical bone plate that had been perforated 8 weeks previously; also evident were ingrowths of marrow tissue and bone formation. In a few specimens some newly formed bone trabeculae were found in the medullary space, both contiguous to the perforated cortical bone plate and as small islets in the marrow tissue. The mean test and control site values for each parameter were similar, and no statistically significant differences were found. In the maxilla, the bone architecture had altered substantially by way of an increase in the proportion of trabecular bone and a decrease in the proportion of cortical bone. Drilling appeared to have little effect on tibial bone density, which did not significantly differ between test and control sites. Maxillary bone density, however, was significantly greater at the test sites than at the control sites. Comparisons of bone density between tibia and jaw specimens revealed no significant differences either between test sides or between control sides. Thus, the same magnitude of surgical trauma that altered the bone architecture and density of the rabbit maxilla was not found to have altered those of the tibia in the same animal 8 weeks after surgery. The reasons for the differences are discussed in this article. Conclusions: As observed 8 weeks post surgery, multiple drill perforations were not found to cause significant alterations in the metaphysis of the tibia whereas a considerable change in bone architecture and an increase in bone density were found in the maxilla. Whether this depends on different embryologic origins or reflects morphologic and functional differences in the mature bone demands further study.     

低幅度高频率振动波对种植体骨结合影响的研究进展

低幅度高频率振动波(low-magnitude high-frequency vibration,LMHFV)作为一种短期、简便、洁净、不良反应少的物理疗法已被证明有一定的成骨效应,LMHFV在身体各部位骨重建中有着积极的作用,也被报道证实其可以促进种植体周围骨的愈合和骨结合.本文就LMHFV的作用机制、传导机制、对种...     

Efficacy of bone morphogenetic protein (BMP) with osteopromotive membranes – an experimental study in rat mandibular defects

The effect of bone morphogenetic protein (BMP) on healing of standardized bone defects was studied with and without the placement of osteopromotive membranes. Two different bovine BMP (bBMP) preparations were tested. These contained primarily collagen as a carrier. Standardized transosseous bone defects, 5 mro in diameter, were created in mandibles of rats. If left untreated, such "critical size defects" never heal during the lifetime of the animal, whereas covering with an osteopromotive membrane is known to cause complete healing of the defects in 6 weeks. The bBMP was implanted in defects and were either covered with an expanded polytetrafluoroethylene (e-PTFE) membrane (GORE–TEX®) or were left uncovered. Control defects did not receive any bBMP and were either covered with membrane or were left uncovered. Histological evaluation was made after 12 d and 24 d of healing, respectively. Implantation of bBMP alone was associated with formation of voluminous amounts of new bone, resulting in essentially complete defect healing at 24 d. However, the combination of membrane and bBMP was dearly less effective in stimulating bone healing, being only about as efficient as when using membranes alone. It was concluded that whereas both bBMP preparations were strongly osteoinductive, no further improvement of bone healing was seen when the membrane technique was supplemented with bBMP, compared to membrane alone. An explanation may be that the presence of an e-PTFE membrane prevents the degradation of the carrier material in the preparations, thus strongly reducing the availability of bBMP.     

Recent outcomes and perspectives of the application of bone morphogenetic proteins in implant dentistry

Background: Since the discovery of bone morphogenetic proteins (BMPs), the number of related studies has increased substantially, and more recent outcomes have cast encouraging perspectives on their use in reconstructive surgery. Purpose: The aim of the present review was to summarize the present knowledge about the use of BMPs in conjunction with dental implants based on the literature. Materials and Methods: Scientific articles dealing with the use of growth factors and bone healing with or without dental implants were searched for on MEDLINE and critically scrutinized. Results: Thirty‐nine scientific reports formed the base for the present review. Whereas the osteoinductive capability of BMPs is well documented, studies on their effects in implant dentistry are still incipient. Preclinical and clinical studies did not show outstandingly good outcomes of the application of BMPs compared with conventional treatments or controls. Conclusions: The number of studies in the field of dental implantology in which BMPs have been used is still too small for establishing clinical protocols of their use in order to improve a recipient bone bed prior to implant placement or to enhance the integration process of an implant.     

Management and Histobacteriological Findings of Mucosal Fenestration: A Report of 2 Cases

This article describes 2 unusual cases of mucosal fenestration associated with necrotic infected teeth, resulting in exposure of the root apex to the oral cavity. Both cases consisted of maxillary incisors with pulp necrosis and radiographic/tomographic evidence of apical periodontitis. Clinically, the root apex was exposed to the oral cavity through a fenestration in both bone and mucosa and covered with bacterial plaque and calculus. These teeth were treated by a combination of nonsurgical and surgical endodontic treatment. During surgery, the root apices were resected to within the alveolus and the fenestrated area covered by the flap. Specimens consisting of the root apex and surrounding soft tissues were subjected to histopathological and histobacteriological analyses. Histobacteriological analysis revealed extensive resorptive defects on the root apices filled with thick bacterial biofilm, irregular detachment of the cementum layers with consequent infection of the underlying spaces, and heavy infection in the apical foramina. The soft tissue specimens exhibited no or minimal inflammation. The 2 cases showed satisfactory postsurgical healing of the hard and soft tissues. Both cases of mucosal fenestration showed root apices covered with dense bacterial biofilms and associated with a bone crypt with no significant inflammatory tissue therein. The 2 cases were successfully treated by conservative approaches involving a combination of nonsurgical and surgical endodontic treatment with root-end resection.     

固定方式对下颌升支矢状截骨术骨愈合影响的实验动物研究

目的：比较不同固定方式对下颌升支矢状截骨术术后骨创愈合情况的影响。方法16只成年犬随机分成4组,各组均行改良的双侧下颌升支矢状截骨术,分别采用4种骨段固定形式：①钢丝结扎固定;②小夹板固定;③双皮质螺钉固定;④夹板及钢丝联合固定。术后6周、12周分别处死每组动物2只,完整取出下颌骨,HE染色,镜下观察骨组织愈合情况。结果：各组均可见颊舌侧皮质骨的骨膜下有新骨形成;各组术后6周和12周时组织学表现基本相同;后两组可见直接骨愈合,愈合时无内骨痂形成,截骨线不易辨认,骨髓腔和截骨区充满新骨。结论：固定模式影响了骨段稳定性和应力分布状态,从而影响了截骨创的骨愈合,良好的固定对减少术后远期骨性复发有积极意义。     

Bone healing pattern in surgically created circumferential defects around submerged implants: an experimental study in dog

Objective: To describe the healing of marginal defects below or above 1 mm of dimension around submerged implants in a dog model. Material and methods: In 12 Labrador dogs, all mandibular premolars and first molars were extracted bilaterally. After 3 months of healing, full‐thickness flaps were elevated in the edentulous region of the right side of the mandible. Two recipient sites were prepared and the marginal 5 mm were widened to such an extent to obtain, after implant installation, a marginal gap of 0.5 mm at the mesial site (small defect) and of 1.25 mm at the distal site (large defect). Titanium healing caps were affixed to the implants and the flaps were sutured allowing a fully submerged healing. The experimental procedures were subsequently performed in the left side of the mandible. The timing of the experiments and sacrifices were planned in such a way to obtain biopsies representing the healing after 5, 10, 20 and 30 days. Ground sections were prepared and histomorphometrically analyzed. Results: The filling of the defect with newly formed bone was incomplete after 1 month of healing in all specimens. Bone formation occurred from the base and the lateral walls of the defects. A larger volume of new bone was formed in the large compared with the small defects. Most of the new bone at the large defect was formed between the 10‐ and the 20‐day period of healing. After 1 month of healing, the outline of the newly formed bone was, however, located at a similar distance from the implant surface (about 0.4 mm) at both defect types. Only minor newly formed bone in contact with the implant, starting from the base of the defects, was seen at the large defects (about 0.8 mm) while a larger amount was detected at the small defects (about 2.2 mm). Conclusion: Marginal defects around titanium implants appeared to regenerate in 20–30 days by means of a distance osteogenesis. The bone fill of the defects was, however, incomplete after 1 month. To cite this article:
Rossi F, Botticelli D, Pantani F, Pereira FP, Salata LA, Lang NP. Bone healing pattern in surgically created circumferential defects around submerged implants: an experimental study in dog.
Clin. Oral Impl. Res 23 , 2012; 41–48.
doi: 10.1111/j.1600‐0501.2011.02170.x