Critical features of periodontal flaps with regard to blood clot stability: A review

BackgroundWound healing is a multifactorial procedure involving different cell types and biological mediators. The principles of wound healing are also applicable to periodontal tissues. The formation and stability of blood clots play a vital role in successful healing of wounds in periodontal tissues. The aim of the present review was to highlight the vital factors of periodontal flaps associated with blood clot stability.HighlightThe data on periodontal regeneration and wound healing have evolved greatly in light of several factors, including space for blood clots and blood clot stabilization. In periodontal osseous defects, the stability of blood clots seems critical to wound healing. If mechanical forces can be managed by wound stabilization, the gingival flap-tooth root interface may show connective tissue repair. However, compromised adhesion is susceptible to mechanical forces and can cause wound breakage and epithelialization.ConclusionThe presence of a thick blood clot may hinder the plasmatic circulation between the recipient bed and graft during the initial stage of healing, which is critical in cases of mucogingival surgery. Root conditioning can also determine the healing consequence by enhancing blood clot adhesion.     

Sinus floor augmentation with simultaneous placement of dental implants in the presence of platelet-rich plasma or recombinant human bone morphogenetic protein-7

The aim of the present study was to evaluate the possible benefit of platelet-rich plasma (PRP) in sinus grafting as compared with recombinant human bone morphogenetic protein-7 (rhBMP-7). For this purpose, we performed a bilateral sinus augmentation with anorganic bovine bone and simultaneous insertion of a titanium screw implant in five miniature pigs. Six hundred microliters of PRP and 15%-vol. autologous bone, which was collected with a trap during preparation of the implant recipient site, were added to the right sinus and 420 microl rhBMP-7 to the left sinus. A polychrome sequential labeling was performed. The animals were sacrificed 6 weeks after surgery. Undecalcified ground sections were evaluated by microradiography, digitized histomorphometry and under fluorescent light. The mean bone-implant contact using rhBMP-7 was 45.8% and 5.7% under PRP (P=0.002). The mean height of newly mineralized bone in the augmented area using rhBMP-7 amounted to 8.3 mm as opposed to 3.6 mm under PRP (P=0.013). Using PRP, the mean area of the newly formed bone was enhanced (51.3%) as compared with rhBMP-7 (33.1%); however, this difference was not statistically significant (P=0.081). In conclusion, under the selected experimental conditions the use of rhBMP-7 led to superior outcomes with regard to the osseointegration of dental implants and the height of new bone as compared with the use of PRP.     

以藻酸钙为载体的可注射性组织工程骨研究

目的：研究藻酸钙／骨髓基质成骨细胞复合物在有免疫动物体内成骨的可行性。方法：从免筋骨中获取骨髓基质成骨细胞，将骨髓基质成骨细胞与25g／L藻酸钠溶胶混合形成藻酸钠／骨髓基质成骨细胞复合物，取其2ml与0．17g硫酸钙粉末混合均匀，注射于新西兰兔背部皮下，观察成骨情况。结果：藻酸钙／骨髓基质成骨细胞复合物植入免皮下四周后有类软骨样组织形成，8周时有骨小梁、骨髓腔等骨组织结构。结论：藻酸钙／骨髓基质成骨细胞复合物通过注射方式在有免疫动物体内可以形成骨组织。     

Reconstructive periodontal therapy with simultaneous ridge augmentation. A clinical and histological case series report

Treatment of intrabony periodontal defects with a combination of a natural bone mineral (NBM) and guided tissue regeneration (GTR) has been shown to promote periodontal regeneration in intrabony defects. In certain clinical situations, the teeth presenting intrabony defects are located at close vicinity of the resorbed alveolar ridge. In these particular cases, it is of clinical interest to simultaneously reconstruct both the intrabony periodontal defect and the resorbed alveolar ridge, thus allowing insertion of endosseous dental implants. The aim of the present study was to present the clinical and histological results obtained with a new surgical technique designed to simultaneously reconstruct the intrabony defect and the adjacently located resorbed alveolar ridge. Eight patients with chronic advanced periodontitis displaying intrabony defects located in the close vicinity of resorbed alveolar ridges were consecutively enrolled in the study. After local anesthesia, mucoperiosteal flaps were raised, the granulation tissue removed, and the roots meticulously scaled and planed. A subepithelial connective tissue graft was harvested from the palate and sutured to the oral flap. The intrabony defect and the adjacent alveolar ridge were filled with a NBM and subsequently covered with a bioresorbable collagen membrane (GTR). At 11-20 months (mean, 13.9+/-3.9 months) after surgery, implants were placed, core biopsies retrieved, and histologically evaluated. Mean pocket depth reduction measured 3.8+/-1.7 mm and mean clinical attachment level gain 4.3+/-2.2 mm, respectively. Reentry revealed in all cases a complete fill of the intrabony component and a mean additional vertical hard tissue gain of 1.8+/-1.8 mm. The histologic evaluation indicated that most NBM particles were surrounded by bone. Mean new bone and mean graft area measured 17.8+/-2.8% and 32.1+/-8.3%, respectively. Within their limits, the present findings indicate that the described surgical approach may be successfully used in certain clinical cases to simultaneously treat intrabony defects and to reconstruct the resorbed alveolar ridge.     

煅石膏、骨形成蛋白及羟基磷灰石三元复合人工骨修复骨缺损的实验研究

以煅石膏(PLP）作为颗粒型羟基磷灰石(HA)人工骨粘接成形剂和骨形成蛋白(BMP)的载体，制成三元复合人工骨．分别用HA—bBMP、HA—PLP和单纯HA植入狗下颌骨实验性骨缺损中，采用组织学、定量组织学、免疫组织化学、X线摄片和扫描电镜观察的方法评价该复合人工骨的生物学性能。术后1，2，4，8和16周观察发现，HA—bBMP—PLP复合人工骨具有明显的骨诱导活性．PLP可充当BMP缓慢释放系统载体．增强BMP骨诱导活性，和作为颗粒型HA的粘接成形剂．使复合人工骨具有一定的可塑性和成形性，可达到准确的植入，植入后早期可有效防止HA颗粒移动。本研究证实．HA—bBMP—PLP三元复合人工骨不但可限制植入后HA颗粒的早期移动，更重要的是可以迅速增加新骨形成量．从形态和功能上大大提高了复合人工骨修复骨缺损的质量。     

吻合旋股外侧血管髂骨移植在颌面部的应用

吻合血管髂骨移植是修复颌骨缺损的常用手术。作者应用吻合旋股外侧血管升支髂骨瓣移植修复颌面部骨缺损４例，证实以该血管为蒂的髂骨瓣的临床可行性。旋股外侧血管升支位置恒定、血管口径较粗，所形成的血管蒂较长，操作安全、方便。作者认为以该血管为蒂的髂骨移植是颌骨缺损修复的可供选择术式之一。本文对该髂骨瓣的血供、手术注意点等进行了讨论。     

Maxillary sinus floor grafting with beta-tricalcium phosphate in humans: density and microarchitecture of the newly formed bone

OBJECTIVES: Graft insertion can effectively enhance the regeneration of debilitated bone. The effects of an alloplastic bone-replacing material, beta-tricalcium phosphate (Cerasorb), and of autogenous bone graft were compared. MATERIALS AND METHODS: In 17 edentulous patients, the maxillary sinus floor was extremely atrophied to such an extent that implant placement was impossible. The Schneiderian membrane was surgically elevated bilaterally by insertion of Cerasorb (experimental side) and autogenous bone graft (control side). After surgery, the recovery was followed clinically and radiologically. After 6 months, 68 bone cylinders were excised from the grafted areas and implants were inserted into their places. The bone samples were embedded into resin, and the osteointegration of the grafts was studied histologically. Trabecular bone volume (TBV) and trabecular bone pattern factor (TBPf) were quantified by histomorphometry. RESULTS: Cerasorb proved to be an effective bone-replacing material with osteoconductivity; it was capable of gradual disintegration, thereby providing space for the regenerating bone. The new bone density was not significantly different on the experimental and control sides (32.4+/-10.9% and 34.7+/-11.9%, respectively). However, the graft biodegradation was significantly slower on the experimental side than the control side. The TBPf value was lower on the control side than on the experimental side (-0.53+/-1.7 and -0.11+/-1.4 mm(-1), respectively), but this difference was not significant. CONCLUSIONS: Six months after insertion of the grafts, the bone of the augmented sinus floor was strong and suitable for anchorage of dental implants, irrespective of whether autogenous bone or Cerasorb particles had been applied.     

Significance of primary stability for osseointegration of dental implants

AIM: To investigate the significance of the initial stability of dental implants for the establishment of osseointegration in an experimental capsule model for bone augmentation. MATERIAL AND METHODS: Sixteen male rats were used in the study. In each rat, muscle-periosteal flaps were elevated on the lateral aspect of the mandibular ramus on both sides, resulting in exposure of the bone surface. Small perforations were then produced in the ramus. A rigid, hemispherical Teflon capsule with a diameter of 6 mm and a height of 4 mm and with a hole in its middle portion, prepared to fit the circumference of an ITI HC titanium implant of 2.8 mm in diameter, was fixed to the ramus using 4 mini-screws. On one side of the jaw, the implant was placed through the hole in such a way that its apex did not make contact with the mandibular ramus (test). This placement of the implant did not ensure primary stability. On the other side of the jaw, a similar implant was placed through the hole of the capsule in such a way that contact was made between the implant and the surface of the ramus (control). This provided primary stability of the implant. After placement of the implants, the soft tissues were repositioned over the capsules and sutured. After 1, 3, 6 and 9 months, four animals were sacrificed and subjected to histometric analysis. RESULTS: The mean height of direct bone-to-implant contact of implants with primary stability was 38.8%, 52.9%, 64.6% and 81.3% of the implant length at 1, 3, 6 and 9 months, respectively. Of the bone adjacent to the implant surface, 28.1%, 28.9%, 52.6% and 69.6%, respectively, consisted of mineralized bone. At the test implants, no bone-to-implant contact was observed at any observation time or in any of these non-stabilized specimens. CONCLUSION: The findings of the present study indicate that primary implant stability is a prerequisite for successful osseointegration, and that implant instability results in fibrous encapsulation, thus confirming previously made clinical observations.     

Extensive augmentation of the alveolar ridge using autogenous calvarial split bone grafts for dental rehabilitation

Free autogenous iliac bone is the most commonly used graft material for an extensive alveolar ridge reconstruction. The application of iliac bone, however, is associated with problems, such as transplant loss resulting from postoperative infection and late bone resorption. A bone-graft material more suitable than iliac bone is therefore still needed. This paper describes a concept for alveolar-ridge reconstruction using calvarial split bone, and the related surgical techniques. Clinical and radiological follow-up examinations were undertaken to evaluate the potential benefit of calvarial split bone in alveolar-ridge reconstruction. Between 1999 and 2002, 13 patients with a mean age of 54 years (range 31-70 years) underwent surgery, seven patients in the maxilla and six in the mandible. In four cases, wound dehiscence occurred postoperatively. In one of these cases, the dehiscence was associated with a local infection. However, no bone transplants were lost. After a mean follow-up time of 19.6 months, bone resorption, measured radiologically, was minimal. Endosseous dental implants were successfully installed and maintained. Satisfactory prosthetic rehabilitation was achieved in all patients. Our preliminary experience suggests that calvarial split bone may be regarded as a promising alternative to autogenous iliac bone in connection with extensive augmentation of the alveolar ridge.     

非血管化游离骨移植中细胞活力的实验研究

目的 :探讨非血管化游离骨块中细胞存活能力及数量与离体时间的关系。方法 :取狗非血管化游离髂骨块 ,在离体 2 5～ 15 0min的不同时间点 ,消化骨块获得细胞 ,进行活细胞计数。对消化获得细胞体外培养2 4h后 ,再进行活细胞计数 ,分析细胞存活与离体时间的关系。结果 :在离体 2 5～ 15 0min时间内 ,骨块细胞的存活率从 91.96%降至 9.5 2 %。统计学检验 ,2 5min组与 70min以前组之间没有统计上的差别 ,P >0 .0 5 ;2 5min组与 70min及其以后组之间有明显差别 ,P <0 .0 1。培养 2 4h后 ,以上各时间点的细胞存活率则从88.73 %到 3 .88% ,组间差别与刚离体时相同 ,但 70min后的各组活细胞率明显下降。结论 :非血管化狗游离髂骨块的离体时间对其中的细胞存活有明显影响 ,离体 70min可能是其关键点 ;在非血管化游离骨移植中 ,尽量缩短骨块的离体时间 ,有利于保存更多的活细胞