应用浓缩生长因子行上颌窦内提升后种植体周围骨变化

背景：许多实验和临床研究报道不使用植骨材料而单纯采用患者静脉血、可吸收胶原海绵、富纤维蛋白凝块等均可促进新骨形成,那么只移植浓缩生长因子在上颌窦内提升中是否也能有效地促进骨再生？目的：以浓缩生长因子作为移植材料行上颌窦内提升,观察种植体周围骨水平的改变。方法：纳入26例患者,其中男14例,女12例,年龄35-73岁,均以自体浓缩生长因子作为移植材料行上颌窦内提升,同期植入Astra Tech种植体。按随访时间分为6-12个月组、13-18个月组与18个月以上组,按术前剩余牙槽骨高度分为≤5 mm组、5-7 mm组与≥7 mm组,按术后上颌窦提升高度分为≤2 mm组、2.0-3.0 mm组与≥3 mm组,随访观察种植体存留率与边缘骨水平变化。结果与结论：共植入种植体44 枚,修复后随访6-18个月,43枚种植体修复成功,种植体存留率为98%。不同随访时间组间近、远中边缘骨水平改变比较差异无显著性意义,显示以浓缩生长因子作为移植材料行上颌窦内提升在随访6-18个月内能形成良好骨结合。不同剩余牙槽骨高度组间的近、远中边缘骨水平改变比较差异无显著性意义,不同窦底提升高度组间的近、远中边缘骨水平改变比较差异无显著性意义,说明剩余牙槽骨高度与上颌窦提升高度对种植体周骨组织形成无明显影响。表明在上颌窦内提升时使用浓缩生长因子移植材料同期植入种植体存留率高,种植体周围牙槽骨稳定,长期效果有待进一步观察。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

上颌窦底骨分隔对内提升术后成骨效果的影响

目的　上颌窦骨分隔被认为是上颌窦内提术的相对禁忌症,文中旨在探讨上颌窦底骨分隔对内提升术后成骨效果的影响。 方法　收集上颌窦底骨分隔需内提升进行种植的患者7例（有分隔组）,另随机选取上颌窦无分隔需进行内提升的患者8例（无分隔组）,共15例,利用CBCT(Cone Beam Computed Tomography)和Simplant软件对植体周围骨高度及骨密度进行测量,采用SPSS19.0软件对数据进行统计分析。 结果　有分隔组及无分隔组的提升高度,植体根尖高度差,颊侧高度差,根尖区骨密度,颊侧骨密度的对比,P值均大于0.05,两组结果差异无统计学意义。 结论　上颌窦底骨分隔内提升术后的成骨效果无明显影响。     

生物膜引导骨再生在上颌窦提升中的成骨效果

背景：利用生物膜引导骨再生技术在上颌窦提升中成骨是牙种植的研究热点。 目的：探讨引导骨再生技术在上颌窦提升中的成骨效果。 方法：9只比格犬进行双侧上颌窦底提升同期牙种植,实验侧行胶原膜覆盖颊侧创口,对照侧无胶原膜覆盖。术后4,12,24周分别处死实验犬,行大体标本、力学测试及组织学检查。 结果与结论：术后12,24周时对照侧骨移植材料有移位,骨质吸收明显,种植体顶部暴露,实验侧种植体顶部骨移植材料无移位现象,有较厚的骨质覆盖。随时间的增加,种植体牵出力增加,在24周时实验侧与对照侧差异有显著性意义(P < 0.05)。组织学检查可见双侧上颌窦底植入骨粉后均可见新生骨形成,随时间延长逐渐增多、成熟,骨粉颗粒逐渐减少,术后12,24周时实验组与对照组新生骨的面积比较差异有显著性意义    (P < 0.05)。结果显示生物膜引导再生技术可减少上颌窦提升后骨的吸收,促进新骨骨形成。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

Ⅱ类骨质下上颌窦区垂直骨高度不足时应用短种植体长度和直径的优化分析

背景：应用短种植体在上颌窦区种植后生物力学指标会有哪些变化？ 目的：建立包含上颌窦的Ⅱ类骨质真实上颌骨模型,观察Ⅱ类骨质下上颌窦区垂直骨高度为9 mm时应用短种植体的最佳的长度和直径范围。 方法：建立包含短种植体的上颌窦区Ⅱ类骨质的骨块三维有限元模型,设定短种植体直径为4~6 mm和长度为6~8 mm,分析直径和长度对颌骨的等效应力峰值。 结果与结论：垂直(颊舌)加载时,随着直径增加,皮、松质骨的等效应力分别下降26%(40%)和31%(45%),随着长度增加,皮质骨和松质骨的等效应力峰值分别下降8%(5%)和0(7%)。两种方式加载时下,当直径 >4.8 mm且长度 >7.5 mm时,颌骨的等效应力峰值对直径和长度的响应曲线曲率位于-1和0之间,变量直径比长度对颌骨的等效应力峰值的影响更明显。结果证实,短种植体的长度和直径的增加可以降低颌骨应力,尤其是直径的增加更有利于改善力学分布,当窦嵴距为9 mm应用短种植体时,直径应 >4.8 mm,长度应 >7.5 mm,可保证其稳定性。     

种植体结构改变对种植体-骨界面皮质骨区应力影响的三维有限元分析

背景：种植体-骨界面的生物力学效应是骨吸收重要的影响因素之一。模仿天然牙周膜的新结构种植体或可改善其界面应力的分布情况。 目的：探讨不同的咬合负载条件下,改变传统种植体内部结构对种植体-骨界面皮质骨区应力分布、峰值的影响,为新结构种植体的优化设计及临床应用提供理论依据。 方法：用Pro/ENGINEER软件建立新结构的种植体(模型A)与无螺纹的传统柱状种植体(模型B)的数字模型,采用Ansys软件分析在相同骨质及相同受力环境下种植体-骨界面皮质骨区应力峰值、应力带分布的变化规律。 结果与结论：垂直加载时,模型A在不同受力大小时应力峰值均较模型B降低17.54%;45°加载时,模型A应力峰值较模型B降低(2.59%),模型B的高应力区向颊侧集中趋势明显。咀嚼模拟加载时,模型A的应力峰值均较模型B低,其差值在施力方向与种植体轴向夹角(β)等于12°时最大(0.353 2 MPa),在β > 12°后逐渐减小;并且模型A在促进骨组织生长最适应力峰值、维持骨组织健康应力峰值两个量化指标中,均比模型B适用角度范围大(A：0°-28°,0°-58°;B：0°-24°,0°-56°)。提示优化设计种植体结构的改变可改善种植体-骨界面皮质骨区的应力分布,降低应力峰值,可在更大范围内降低骨皮质吸收的风险。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

天然上颌中切牙与种植体应力规律的三维有限元分析

背景：生物力学相容性是保证种植体与骨结合后长期稳定并行使功能的必要条件,因此,了解上颌中切牙与其周围骨组织应力应变分布情况对种植义齿修复尤为重要。 目的：根据天然牙5种不同解剖分型,探讨上颌中切牙牙根与种植体的应力分布规律。 方法：根据天然上颌中切牙5种不同解剖分型,通过UGNX、ANSYS等软件建立种植体及周围局部结构的三维有限元模型(B1、B2、M1、M2、P1),对种植体施加与牙长轴的夹角成0°、30°、45°、60°、90°的100 N静态荷载力,分析5类上颌中切牙牙根与种植体的应力分布情况。 结果与结论：5种分型中,天然中切牙与种植体等效应力随着加载力角度的增大而增大,种植体上升趋势高于天然牙。天然牙等效应力最大值集中在B1,最小值在M1,而种植体等效应力最大值在M1,最小值在M2。天然牙牙根等效应力有2%-31%的差距,种植体等效应力有4%-21%的差距,种植体的应力分布区间小于天然牙牙根的应力分布区间。说明种植体与天然牙随着咬合力角度的增大与受力呈正比,种植体所能承受的咬合力小于天然中切牙。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

不同牙种植体系统对种植体周围骨组织吸收的影响

BACKGROUND: The peri-implant bone absorption is closely related to the repair effect. OBJECTIVE: To compare the effects of three kinds of dental implant systems on the peri-implant bone absorption. METHODS: 116 patients who underwent the dental implant systems were collected, including 46 cases with 3I implant system, 40 cases with ITI implant system and 30 cases with BLB implant system. The peri-implant bone absorption, sulcus bleeding index and periodontal probing depth of three groups were detected at 1, 3, 6, 9 and 12 months after implantation, respectively. RESULTS AND CONCLUSION: The peri-implant bone absorption of three groups within 1 year after implantation was in a rise, and the bone absorption of BLB group was significantly higher than that of ITI and 3I groups at 3 and 12 months after implantation (P < 0.05). Compared with the natural teeth, the gingival sulcus bleeding index of three groups were all increased at different time points after implantation; the gingival sulcus bleeding index of BLB group was significantly higher than that of natural teeth at 6 months after implantation (P < 0.05); the gingival sulcus bleeding index of three groups were significantly higher than that of natural teeth at 9 months after implantation (P < 0.05). The periodontal probing depth of three groups showed an ascending trend at 6 months after implantation; the periodontal probing depth of three groups was higher than that of natural teeth at different time points after implantation, which exhibited significant differences at 6 and 9 months after implantation (P < 0.05). In conclusion, three kinds of dental implant systems exhibit differet effects on the peri-implant bone absorption, but all achieve excellent clinical efficacies.     

平台转移设计种植体植入1年后下颌后牙区的骨丧失

背景：传统两段式种植体修复后种植体颈部牙槽骨的吸收一直被认为是种植术后的正常反应。 目的：评价下颌后牙区两段式种植体应用平台转移设计后周围骨丧失情况。 方法：50例患者共植入88颗种植体,实验组植入40颗Ankylos种植体,采用平台转移设计;对照组植入48颗3i种植体,采用传统对接设计。所有种植体均为潜入式植入,肩台均平齐牙槽嵴顶水平,3个月后完成最终修复。 结果与结论：所有种植体均完成骨结合。与种植体植入时相比,功能负重12个月后,实验组种植体周围骨丧失高度为(0.31± 0.39) mm,对照组种植体周围骨丧失高度为(0.94±0.43) mm,两者差异有非常显著性意义。随访期内,种植体无松动、脱落,牙龈组织健康,成功率为100%。结果显示种植体功能负重12个月后,平台转移设计可以减少种植体颈部骨吸收,保持种植体周围骨组织的稳定性。     

高度吸收的上颌窦区种植体生物力学分析

背景：目前有限元法广泛应用于骨科生物力学分析,评价指标主要包括Max von Mises 应力和应力的传递和分布概况。但由于体内的复杂生物力学环境和个体化差异明显,很难由具体的案例得出解决临床相关的方法。 目的：分析高度吸收上颌窦区种植体的生物力学分布状况。 方法：应用Simplant建立了一个位于上颌第二磨牙位置的5.5 mm×11.0 mm植入体模型;Abaqus有限元软件分别分析了在正咬合和反咬合关系条件下,在0°,30°,45°,60°,90°负载300 N的同等加载下,其上颌窦区域的应力分布情况,并作了比较。 结果与结论：在反咬合关系下,上颌骨内的应力集中均匀分布在牙植体颈部与皮质骨的交界处,在0°,30°,45°,60°,90°负载300 N的同等加载下,Max von Mises分别是23.43,52.97,61.18,66.15,70.53 MPa。在正咬合关系下,上颌骨内的应力集中不仅分布在牙植体颈部与皮质骨的交界处,而且出现了第二应力集中区,Max von Mises分别是38.64,71.22,71.62,77.65,73.21 MPa,较反咬合平均高出50%左右。实验有限元分析结果表明,高度吸收上颌窦区采用反咬合设计方法更好。     

60Co放射及微量元素锌对钛种植体骨融合的影响

背景：前期实验证实补锌可以加速种植体的骨融合。目的：观察⁶⁰Co放射及微量元素锌对种植体骨融合的影响。方法：取成年雄性家兔36只,双侧胫骨近心端各植入1枚钛种植体,建立钛种植体动物模型,随机均分为4组,补锌组种植后24 h肌注10 g/L硫酸锌4 mg/kg,1次/d;对照组种植后24 h肌注9 g/L生理盐水4 mg/kg,1次/d;放射组于种植后第2,4,6天给予双侧胫骨近心段⁶⁰Co照射,15 Gy/d,同时种植后24 h肌注9 g/L生理盐水4 mg/kg,1次/d;放射补锌组于种植后第2,4,6天给予双侧胫骨近心段⁶⁰Co照射,15 Gy/d,同时种植后24 h肌注10 g/L硫酸锌4 mg/kg,1次/d。种植后1,4,12周利用显微镜观察种植体骨界面组织形态。结果与结论：在相同时间段内,与其他各组相比,放射组种植体周围成纤维细胞数量较多,纤维性结合较多,而骨性组织特别是成熟骨组织形成较少。在相同时间段内,与其他各组相比,补锌组种植体表面成骨细胞数量更多,骨性结合更多,在第4周时即可见成熟骨组织出现,说明补锌能在种植后早期(1-4周)即形成骨性愈合。放射补锌组在第4,12周时也较放射组产生更多骨性结合,说明即使在⁶⁰Co照射后,微量元素锌的补充仍可以促进种植体-骨融合。提示⁶⁰Co照射会延缓种植体骨愈合,放射治疗后适量补锌能够减轻其对种植体骨融合的不利影响。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

Biomechanical analysis of the effects of implant diameter and bone quality in short implants placed in the atrophic posterior maxilla

Short dental implant (SDI) placement has been proposed as an alternative to reduce the surgical risks related to the advanced grafting procedures. The aim of this study was to simulate the biomechanical behaviors and influences of SDI diameters under various conditions of bone quality by using a validated finite element (FE) model for simulation. The CT image and CAD system were combined to construct the FE models with 6 mm length SDIs for 6, 7 and 8 mm diameters under three types of bone qualities, from normal to osteoporotic. The simulated results showed that implant diameter did not influence the von Mises strains of bone under the vertical load. The bone strains increased about 58.58% in the bone of least density under lateral load. Lateral loads induced high bone strain and implant stress than vertical loads. The bone strains of 7 mm- and 8 mm-diameter short implants were not different, and both were about 52% and 66% compared to those of 6 mm-wide short implant under lateral loads. The von Mises stress of the SDIs and their compartments were all less than the yield stress of the material under vertical and lateral loads. SDIs with diameter of 7 mm or above may have better mechanical transmission in the same length at feasible condition. Attaining a proper occlusal scheme design or selective occlusal adjustments to reduce the lateral occlusal force upon the SDIs is recommended.     

Osteoblasts engulf apoptotic bodies during alveolar bone formation in the rat maxilla

During bone formation, as in other tissues and organs, intense cellular proliferation and differentiation are usually observed. It has been described that programmed cell death, i.e., apoptosis, takes place in the control of the cellular population by removing of the excessive and damaged cells. Although it is generally accepted that apoptotic bodies are engulfed by professional phagocytes, the neighboring cells can also take part in the removal of apoptotic bodies. In the present study, regions of initial alveolar bone formation of rat molars were examined with the aim to verify whether osteoblasts are capable of engulfing apoptotic bodies, such as professional phagocytes. Rats aged 11-19 days were sacrificed and the maxillary fragments containing the first molar were removed and immersed in the fixative solution. The specimens fixed in glutaraldehyde-formaldehyde were processed for light microscopy and transmission electron microscopy. For the detection of apoptosis, the specimens were fixed in formaldehyde, embedded in paraffin, and submitted to the TUNEL method. The results revealed round/ovoid structures containing dense bodies on the bone surface in close contact to osteoblasts and in conspicuous osteoblast vacuoles. These round/ovoid structures showed also positivity to the TUNEL method, indicating that bone cells on the bone surface are undergoing apoptosis. Ultrathin sections showed images of apoptotic bodies being engulfed by osteoblasts. Occasionally, the osteoblasts exhibited large vacuoles containing blocks of condensed chromatin and remnants of organelles. Thus, these images suggest that osteoblasts are able to engulf and degrade apoptotic bodies.     

Assessment of bone channels other than the nasopalatine canal in the anterior maxilla using limited cone beam computed tomography

Purpose

The anterior maxilla, sometimes also called premaxilla, is an area frequently requiring surgical interventions. The objective of this observational study was to identify and assess accessory bone channels other than the nasopalatine canal in the anterior maxilla using limited cone beam computed tomography (CBCT).

Methods

A total of 176 cases fulfilled the inclusion criteria comprising region of interest, quality of CBCT image, and absence of pathologic lesions or retained teeth. Any bone canal with a minimum diameter of 1.00 mm other than the nasopalatine canal was analyzed regarding size, location, and course, as well as patient gender and age.

Results

A total of 67 accessory canals ≥1.00 mm were found in 49 patients (27.8 %). A higher frequency of accessory canals was observed in males (33.0 %) than in females (22.7 %) (p = 0.130). Accessory canals occurred more frequently in older rather than younger patients (p = 0.115). The mean diameter of accessory canals was 1.31 ± 0.26 mm (range 1.01–2.13 mm). Gender and age did not significantly influence the diameter. Accessory canals were found palatal to all anterior teeth, but most frequently palatal to the central incisors. In 56.7 %, the accessory canals curved superolaterally and communicated with the ipsilateral alveolar extension of the canalis sinuosus.

Conclusions

The study confirms the presence of bone channels within the anterior maxilla other than the nasopalatine canal. More than half of these accessory bone canals communicated with the canalis sinuosus. From a clinical perspective, studies are needed to determine the content of these accessory canals.     

双维控制牙槽骨牵张器的成骨效应

背景：牵张成骨增高牙槽嵴在基础研究及临床已有很多成功报道,双维控制垂直牙槽骨牵张器可有效防止单向直线牵张器行牙槽骨牵张发生轴向移位。 目的：研制双维控制的牙槽骨牵张器,并通过动物实验观察其成骨效应。 方法：选择杂种犬4只,拔除一侧下颌前磨牙形成萎缩牙槽骨模型。1个月后行骨切开放置双维牵张器,7 d后垂直牵张 (1 mm/d,共5 d)。完成垂直牵张后,利用双维牵张器颊向控制功能将移动骨块颊向牵出(大约2.4 mm),固定2个月后行大体观察及组织学检查。 结果与结论：4只犬中2只黏膜伤口愈合良好,2只黏膜出现裂开,行二次缝合后愈合,牵张器固位良好,未出现松动、脱落。牵张骨块向垂直向及颊向的位移量满足实验目的要求,牙槽骨垂直向高度平均增加(5.0±0.2) mm,颊向宽度平均增加(2.4±0.3) mm。大体观察及组织学检查均证实牵张成骨的骨块新骨形成良好。说明双维控制垂直牙槽骨牵张器能较好的控制移动骨块垂直或颊向的移动方向,并且新骨形成良好。     

Clinical anatomy of the posterior maxilla pertaining to Le Fort I osteotomy in Thais

This article studies the anatomy of the posterior maxilla pertaining to bone-cut design of Le Fort I osteotomy to avoid the injury to the descending palatine artery in Thais. Fifty-five skulls (38 males, 17 females) were assessed for the anatomical landmarks by a combination of direct inspection, computerized imaging, and computed tomography scan analysis. The results showed that 27.28% of the pterygomaxillary junction (PMJ) became synostosis. The mean heights of the PMJ, posterior maxilla, and maxillary tuberosity were 15.14 +/- 2.46 mm, 22.51 +/- 3.50 mm, and 7.45 +/- 2.76 mm, respectively. The mean length of the medial sinus wall measuring from the piriform rim to the descending palatine canal at the Le Fort I level was 34.40 +/- 2.96 mm. The mean widths of the posterior incision of Le Fort I osteotomy at the maxillary tuberosity and PMJ were 20.38 +/- 2.82 mm and 11.60 +/- 1.57 mm. The mean length of the posterior maxilla was 27.18 +/- 2.49 mm. Distances from the greater palatine foramen to the maxillary tuberosity incision and PMJ incision were 1.76 +/- 1.12 mm and 3.59 +/- 1.40 mm. The mean angle between the descending palatine canal and the hard palate was 57.33 +/- 4.54 degrees . There were no significant differences in any measurements between sides and genders, except the pterygoid process width and posterior maxilla length of males were longer than those of females (P < 0.05). This study could provide better understanding of the posterior maxillary anatomy that is important for the bone-cut design of Le Fort I osteotomy to avoid excessive intraoperative and postoperative hemorrhage including ischemia of the mobilized maxilla.     

Effects of implant drilling parameters for pilot and twist drills on temperature rise in bone analog and alveolar bones

This study concerns the effects of different drilling parameters of pilot drills and twist drills on the temperature rise of alveolar bones during dental implant procedures. The drilling parameters studied here include the feed rate and rotation speed of the drill. The bone temperature distribution was analyzed through experiments and numerical simulations of the drilling process. In this study, a three dimensional (3D) elasto-plastic dynamic finite element model (DFEM) was proposed to investigate the effects of drilling parameters on the bone temperature rise. In addition, the FE model is validated with drilling experiments on artificial human bones and porcine alveolar bones. The results indicate that 3D DFEM can effectively simulate the bone temperature rise during the drilling process. During the drilling process with pilot drills or twist drills, the maximum bone temperature occurred in the region of the cancellous bones close to the cortical bones. The feed rate was one of the important factors affecting the time when the maximum bone temperature occurred. Our results also demonstrate that the elevation of bone temperature was reduced as the feed rate increased and the drill speed decreased, which also effectively reduced the risk region of osteonecrosis. These findings can serve as a reference for dentists in choosing drilling parameters for dental implant surgeries.