拔牙区骨改建对牙齿移动影响的组织学及组织形态测量学研究

目的 :探讨不同愈合阶段的拔牙区内骨密度及骨质结构对牙齿移动的影响 ,以及邻牙向不同愈合阶段的拔牙区内移动时的组织学变化 ,确定邻牙向拔牙区移动的最佳时机。方法 :选择同源 13周龄雄性、SPF级SD大鼠 3 0只 ,分成 3个实验组。3组动物均拔除上颌第一磨牙 ,分别在拔牙后 1、7、2 1d戴用统一规格的矫治器牵第二磨牙向拔牙区移动。所有大鼠在实验结束处死后 ,将上颌骨解剖制备硬组织切片和组织学切片。通过大体标本及组织学观察、组织形态测量等手段 ,研究拔牙区骨改建对牙齿移动的影响。结果 :随着拔牙后间隔时间延长 ,拔牙区骨密度逐渐增加 ,骨结构日趋致密、牙移动逐渐减少 ;拔牙后立即移动牙齿 ,更容易引起根尖牙周组织损害及牙根吸收。结论 :拔牙后应早期移动牙齿 ,其理想的移动时机为拔牙后 1周左右。     

拔牙区骨改建对邻牙移动速度的影响

目的　本研究通过对拔牙创的骨改建进程及矫治力对牙齿移动的影响进行研究,为临床医生选择理想的矫治力和牙齿移动时机,缩短矫治时间提供依据。方法　取SD大鼠36只,随机分为3组,全麻下拔除一侧上颌第一磨牙,3月后拔除另一侧上颌第一磨牙。在拔牙后不同的时间制作口内矫治器,分别以0·30、0·60、1·36 N的力牵上颌第二磨牙向拔牙区移动,分别在施力前及施力后的第1、3、5、7、10、14天拍摄X线片,利用图像处理技术, 测量牙齿移动距离,以置入的拔髓针校正放大率。结果　①牙齿向新鲜拔牙区移动的速度明显大于向已愈合拔牙区移动的速度。②无论向新鲜拔牙区移动还是向已经愈合的拔牙区移动,0·30 N力组牙齿移动的距离在各时间点与0·60 N、1·36 N力组牙齿移动的距离之间存在显著的统计学差异;而0·60 N与1·36 N力组牙齿移动的距离之间基本上从第5天开始差别不大。③加力后牙齿移动周期一般包括三个阶段:瞬时运动;迟滞期;后期移动阶段。大约在第14天时,由于矫治力衰减,牙齿停止移动。结论　①牙齿向新鲜拔牙区移动速度快,而向已经愈合的拔牙区移动速度慢。②在矫治过程中,中等力较为合适;即使使用较大的力,也不一定引起较大的牙齿移动。     

大鼠正畸牙槽骨改建初期转化生长因子β1的表达及意义

目的观察大鼠正畸牙齿移动过程中转化生长因子(TGF-β1)在牙槽骨的表达,探讨其在牙槽骨改建中的调控作用.方法选用25只雄性SD大鼠采用别针簧推上颌切牙向两侧移动的方法,建立牙齿移动及牙槽骨改建模型,并于加力后1d、3d、5d、7d、处死动物取材.用HE染色方法观察牙槽骨的组织学变化,用免疫组织化学方法系列观察牙槽骨中TGF-β1的表达,并检测牙槽骨中增殖细胞核抗原(PCNA)的表达.结果正常牙槽骨组织中,TGF-β1在骨细胞和骨髓组织呈弱阳性表达.牙齿移动3d,压力测牙周膜中前体破骨细胞数量增多,TGF-β1呈阳性表达;张力侧骨髓组织中的TGF-β1免疫反应增强.牙齿移动5d,压力侧的骨吸收陷窝内可见多核破骨细胞,张力侧的牙槽边缘也出现成骨细胞,TGF-β1均呈阳性表达.牙齿移动7d时,张力侧出现少量PCNA呈阳性表达.结论正畸牙齿移动初期,压力侧破骨细胞功能活跃,张力侧面骨细胞的增殖活性随时间逐渐增强.TGF-β1参与了正畸牙槽骨改建初期破骨细胞和成骨细胞的分化形成过程,它是正畸牙槽骨改建中一种重要的局部调控因子.     

大鼠正畸牙移动过程中牙槽骨组织学改变观察

目的 :通过在大鼠上颌第一磨牙施加正畸力 ,观察加力后不同时期受试牙压力侧与张力侧组织学变化。方法 :选用 15只健康成年雄性SD大鼠 ,随机分为 4个实验组及 1个对照组 ,每组 3只。实验组上颌第一磨牙施以 5 0 g力值 ,分别于术后 1、3、7、14天处死并取材 ,常规HE染色 ,于光镜下行组织学观察。结果 :压力侧牙槽骨潜掘性骨吸收的高峰期发生在加力后 3天左右 ,至第 7天基本结束 ;在牙齿移动后期该侧还有新骨生成现象 ,主要表现为加力后 14天有新骨形成 ;张力侧牙槽骨改建以骨生成为主 ,在加力后7天最为显著 ;尔后该侧新生牙槽骨逐步矿化。结论 :大鼠第一磨牙在受到正畸力后 ,其张力侧与压力侧分别按照各自的规律发生重建。     

机械敏感离子通道Piezo1在糖尿病大鼠牙移动过程中的表达和功能研究

目的 研究糖尿病大鼠正畸牙齿移动中张力侧牙周组织内Piezo1的表达变化,探索其在张力侧牙周组织改建中的作用。方法 选取60只健康雄性Wistar大鼠为研究对象,分成对照组以及糖尿病组,以双侧切牙为支抗施加40 g拉伸力近中移动左侧第一磨牙,分别在0、7、14 d处死大鼠后获得左上后牙区牙槽骨块。HE染色检测组织形态变化,免疫组化及荧光染色检测张力侧Piezo1、Osterix以及Runx2的表达水平,Micro-CT检测张力侧骨组织相关参数指标。结果 正畸牙移动激活了张力侧牙周膜中Piezo1的表达,糖尿病大鼠Piezo1以及成骨分化关键转录因子Osterix和Runx2的表达显著低于健康大鼠。结论 糖尿病显著抑制了正畸牙移动过程中张力侧牙周膜中Piezo1的表达,降低了张力侧成骨活性,抑制正畸牙移动张力侧牙周组织的改建。     

成骨诱导剂对拔牙创愈合的影响

目的 探讨以明胶海绵为载体,地塞米松、维生素C和β-甘油磷酸钠组成的成骨诱导剂对拔牙创愈合和牙槽嵴形态改建的影响。方法选用50只家兔,拔除双侧上颌第一前磨牙,右侧拔牙创内填入载有成骨诱导剂的明胶海绵,作为实验侧;左侧填入空载明胶海绵,作为对照侧。拔牙后第1、2、4、8、12周各处死10只动物,取双侧牙槽骨标本,拍摄X线片,并测量骨缺损区新骨密度;用组织学方法评价拔牙创愈合情况;并于12周时,测量拔牙区牙槽嵴高度吸收值。结果X线片骨密度测量显示：术后2、4、8、12周,实验侧骨密度值均高于对照侧,差异有统计学意义（P<0.01）。组织学检查显示：实验侧拔牙创内成骨现象较对照侧早,成骨细胞分化和增殖更活跃。
12周时实验侧牙槽嵴高度吸收值小于对照侧,差异有统计学意义（P<0.01）。结论 由地塞米松、β-甘油磷酸钠和维生素C组成的成骨诱导剂能促进拔牙创愈合,加速成骨和骨改建。     

大鼠正畸牙移动张力侧牙周组织中CTGF基因表达的研究

目的：检测正畸牙移动张力侧CTGF基因表达变化及时间分布特点,初步探讨正畸牙移动中牙槽骨改建与CTGF的关系。方法：45只雄性S.D.大鼠随机分为正常对照组,牙移动12h组、1d组、2d组、3d组、5d组、7d组、14d组、21d组,对大鼠上颌第一磨牙近中移动,运用原位杂交实验方法,检测正畸牙移动张力侧CTGF基因表达强度及时间分布特点。结果：牙移动1 d后牙槽骨表面的立方形活跃成骨细胞CTGFm RNA阳性表达开始增强,7 d后达到高峰,然后逐渐下降。结论：正畸牙移动过程中,在机械力作用下CTGF可能参与了张力侧的骨形成。     

拔牙区牙槽骨改建对牙齿移动的影响

拔牙区牙槽骨改建对牙齿的移动有直接的影响，国内外许多学得对此进行了研究。作者在该文中论述了拔牙区牙槽骨的改过程，牙齿向拔区移动的牙齿的移支方式，以及向拔牙移动对移移动牙和邻牙牙周状况的影响诸多问题，认为充分了解拔牙区牙槽骨的改过程和牙齿了向拔牙区移动的生物学机理，有助于临床医生有效控制牙齿移动，缩短疗程。     

兔牙在牙槽骨缺损修复后正畸移动的组织学观察

目的 了解兔牙在牙槽骨缺损修复区的正畸移动情况。方法 选择20只新西兰大白兔,建立一侧下颌牙槽骨缺损模型,植入骨复合材料加Bio-gide膜,作为实验侧,另一侧为对照侧。8周后,用0.784 N力牵引第一磨牙近中移动,12周时制备组织学标本观察两侧第一磨牙牙根周骨组织改建的情况。结果 2组牙牙根压力侧固有牙槽骨表面可见大量骨吸收陷窝,陷窝中可见新骨沉积,张力侧固有牙槽骨表面可见大量成骨细胞及新生骨;半定量分析研究破骨细胞分化因子和骨保护素的表达在实验侧和对照侧未发现差异(P>0.05)。结论 兔牙槽骨缺损修复8周后可以进行正畸牙移动,矫治力大小可与正常牙槽骨上的牙一致。     

罹患重度牙周炎上颌磨牙拔除后运用微翻瓣牙槽嵴保存术简化种植治疗复杂性（附1例2年随访报告）

罹患重度牙周炎的患牙常伴有严重的感染和牙槽骨破坏,而且拔牙后牙槽窝在愈合过程中进一步骨吸收和改建,增加了后期以修复为导向的种植治疗难度。在上颌磨牙区因毗邻上颌窦,种植治疗常需要进行上颌窦提升术来弥补垂直骨量不足。文章展示了1例罹患重度牙周炎的上颌磨牙,通过微创拔牙后彻底清除牙槽窝感染,结合微翻瓣牙槽嵴保存术,有效减少牙槽窝愈合过程中的骨吸收,实现牙槽嵴的保存和重建,为后期种植修复提供了良好的硬组织三维条件。这一方法将上颌磨牙区骨增量术前移,简化了后续种植治疗的复杂性,值得临床推广应用。     

Effect of appliance reactivation after decay of initial activation on osteoclasts, tooth movement, and root resorption

Clinical orthodontists frequently reactivate appliances following decay. Studies of tooth movement and tissue responses following reactivations indicate that linear tooth movement and rapid recruitment of osteoclasts can be achieved if reactivation is timed to coincide with the latter part of the bone remodeling cycle initiated by the first activation. Both can be delayed if reactivations are timed for the early part of the previous cycle. The objective of this study was to examine tooth movement, root resorption, and osteoclast recruitment following appliance reactivation after the first activation had decayed. Bilateral orthodontic appliances were activated with 40 cN in 144 rats to mesially tip the maxillary molars. After 16 days, rats were randomized into two groups of 72. In group 1, appliances were reactivated in precisely the same manner as the first activation. In group 2, appliances were sham-reactivated. Rats were sacrificed at 1, 3, 5, 7, 10, and 14 days. Orthodontic movement was measured cephalometrically; changes in osteoclasts and root resorption were assessed at both compression and tension sites histomorphometrically; tartrate-resistant acid phosphatase (TRAP) was measured in alveolar bone and serum biochemically. Orthodontic tooth movement was linear in group 1, but osteoclasts required 3 to 5 days to appear. There were no group- or time-related differences in root resorption. Bone TRAP levels were elevated in both groups but dropped significantly (p<0.01) in group 2 at day 7. Appliance reactivations that followed decay of the first activation produced efficient tooth movement without increased risk of root resorption, but these changes were not accompanied by rapid osteoclast recruitment at compression sites. Timing appliance reactivations for the latter portion of the previous bone remodeling cycle could have significant clinical advantages because the delay period seen in tooth movement following a single activation or short-term reactivation can be avoided.     

MMP-3及TIMP-1在正畸牙周组织改建过程中的表达

目的：探讨大鼠正畸牙周组织改建过程中基质金属蛋白酶－３（ＭＭＰ－３）和金属蛋白酶组织抑制因子－１（ＴＩＭＰ－１）与正畸牙齿移动的关系。方法：在ＳＤ成年大鼠上颌左侧第一磨牙上颌切牙之间安置正畸装置,建立大鼠上移动实验模型。于牙齿移动１、３、５、７、１４ｄ后取材分别进行免疫组化染色,图像分析,观察ＭＭＰ－３和ＴＩＭＰ－１表达的变化。结果：牙齿移动１ｄ后,牙周组织细胞ＭＭＰ－３表达增强,５ｄ后ＭＭＰ－３     

Later orthodontic appliance reactivation stimulates immediate appearance of osteoclasts and linear tooth movement

Background: Delays in the appearance of osteoclasts at compression sites occur after orthodontic appliance reactivation, when this is done during both the period of osteoclast recruitment and the peak expansion in the osteoclast population. This experiment examines osteoclasts and tooth movement in alveolar bone after appliance reactivation coinciding with alveolar bone formation and the time when reactivation osteoclasts first appear (ie, 10 days after initial appliance activation). Methods: Bilateral orthodontic appliances were activated to mesially tip maxillary molars with 40 cN in 144 rats. After 10 days, all rats were randomized into two groups of 72. Group I had appliances reactivated in precisely the same manner as the first activation. Group II had appliances sham-reactivated. Nine to 12 rats were then sacrificed at 1, 3, 5, 7, 10, and 14 days in both groups (eg, day 1 represents an interval of 11 days after the first appliance activation and 1 day after either sham or real reactivation). Orthodontic movement was measured cephalometrically; changes in osteoclasts and root resorption were assessed at both compression and tension sites histomorphometrically. Results: Teeth in the reactivated group (Group I) displayed linear tooth movement (62.6 μm/day), and 0.9 mm tooth movement by day 10. Significant increases in osteoclast numbers, osteoclast surface percentage, and surface per individual osteoclast were evident in these animals by 1 day postreactivation (P < .01). Significant treatment-related increases in root resorption were not evident at compression sites at any time. Conclusions: These findings indicate that, after appliance reactivation during the time when reactivation osteoclasts appear, a second cohort of osteoclasts can be recruited immediately, along with immediate and substantial tooth movement and no greater risk of root resorption. (Am J Orthod Dentofacial Orthop 1998;114:692-7)     

The Expression of MMP—3 and TIMP—1 During Orthodontic Periodontium Remodeling in Rats

目的：观察大鼠正畸牙周组织改建过程中基质金属蛋白酶—3(MMP—3)和金属蛋白酶组织抑制因子—1(TIMP—1)表达的变化，探讨MMP—3及TIMP—1与正畸牙齿移动的关系。方法：在SD成年大鼠上颌右侧第一磨牙与上颌切牙之间安置正畸装置，建立大鼠磨牙移动实验模型。于牙齿移动1、3、5、7、14d后取材分别进行免疫组化染色、图像分析。结果：牙齿移动1d后，牙周组织细胞MMP—3表达增强，5d后MMP—3表达达到高峰，此时破骨细胞脑浆亦呈强阳性表达。以后MMP—3表达有所下降，但仍高于对照组。而TIMP—1于牙齿移动3d后表达开始增强，7d后显著表达。结论：MMP—3及TIMP—1参与了正畸牙周组织改建过程，MMP—3在破骨细胞性骨吸收中起着重要作用。     

Temporal and spatial mRNA expression of bone sialoprotein and type I collagen during rodent tooth movement.

To investigate the mechanism of bone formation during tooth movement, in situ hybridization was performed with digoxigenin-labelled RNA probes to detect bone sialoprotein (BSP) and type I collagen mRNAs in the dentoalveolar tissue of 72 Sprague-Dawley rats. An elastic band was inserted between the first and second right maxillary molars, and the teeth experimentally moved for 1, 3, and 7 days. The left first maxillary molar was used as the control. For the untreated molars, osteoblasts and osteocytes near the distal surface of the interradicular septum (IRS) expressed a high level of both BSP and type I collagen mRNAs, while cells on the mesial side of the IRS showed a low level of these mRNAs. For the first molars subjected to experimental tooth movement, a high level of type I collagen mRNA expression was found in the osteoblasts on the tension side of the IRS after 1 day of experimental tooth movement. A high level of BSP mRNA was detected after 3 days of experimental tooth movement. However, a negligible amount of both mRNAs was found in cells on the compression side. These results support the hypothesis that BSP may be involved in mineralization during physiological bone remodelling. On application of orthodontic force, osteoblasts were activated and induced to express BSP mRNA, which is involved in bone remodelling due to orthodontic force. In addition, response to the orthodontic force was observed in osteocytes.     

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目的建立实验性正畸牙移动保持期的动物模型,以利于研究保持期骨改建规律。方法于2008年4月在吉林大学口腔医院动物实验室,选用36只8周龄雄性Wister大鼠,以上颌前牙为支抗牵引第一磨牙向近中移动,加力21d后去除加力装置。以每只大鼠的左侧牙弓为实验侧,右侧牙弓为对照侧。在实验侧安装保持装置,分别保持1、3、7、14、21、28d;对照侧不做任何处理。在加力结束后和保持结束后即刻制取上颌石膏模型,测量所有模型的第一磨牙面近中沟与第二磨牙面远中沟的距离,计算加力结束后与保持结束后的距离,比较实验侧与对照侧的牙齿移动距离,评价保持装置的有效性。结果实验侧在保持结束后第一磨牙复发距离明显小于对照侧,二者差异有统计学意义(P<0.05)。结论以Wister大鼠为实验对象,采用正畸结扎丝结扎法建立的正畸牙移动保持期动物模型是有效的。     

Expression of cathepsin K mRNA during experimental tooth movement in rat as revealed by in situ hybridization

The expression of cathepsin K. a novel collagenolytic enzyme specifically expressed in osteoclasts, was investigated in the rat maxillary dentoalveolar unit during experimental tooth movement by in situ hybridization histochemistry with a non-radioisotopic cRNA probe for rat cathepsin K. Orthodontic elastics were inserted into the interproximal space between the maxillary first and second molars of 7-week-old male SD rats according to Waldo's method and sections prepared from tissues obtained at 12 hr, 1, 2, 3, 4, 7, and 12 days after orthodontic force application. Cathepsin K mRNA expression was detected in the mono- and multinuclear osteoclasts on the pressure side of the alveolar bone at 12 hr after force application, and the distribution and number of cathepsin K mRNA-positive osteoclasts increased time-dependently on the pressure side. At 3-4 days, a marked increase in cathepsin K mRNA-positive osteoclasts was found not only on the pressure side but also on the tension side of the alveolar bone in response to tooth movement. At 7-12 days, the cathepsin K mRNA-positive osteoclasts on both sides had disappeared. These findings suggest that the recruitment of osteoclasts on the pressure side begins during the initial stage of orthodontic tooth movement and the site-specific early induction of cathepsin K mRNA may cause an imbalance in the relative resorption activities on the pressure and tension side incident to such movement.     

Mandibular second molar periodontal status after third molar extraction.

BACKGROUND: Extraction and treatment of third molars have been cited as causing periodontal problems. To evaluate the long-term effects of third molar extraction on the periodontal health of the mandibular second molar, a comparison of the periodontal status was performed around 2 groups of mandibular second molars, with and without third molar extraction. METHODS: A total of 312 sites in 57 adult periodontitis patients were examined and the buccal and lingual locations of the mesial and distal root surfaces around the second molars were recorded. Two-hundred and thirty-two sites were experimental teeth; i.e., third molars had been surgically removed more than 5 years ago, 80 sites served as control molars; i.e., congenitally missing third molars. Clinical periodontal parameters including probing depth, attachment loss, and gingival recession and radiographic intrabony level were measured. The effects of the surgery and the examination (buccal or lingual) locations on the measurements were statistically analyzed. RESULTS: Neither extraction history nor examination location affected the probing depth on mesial surfaces. However, significant effects of the surgical history on the probing depth were observed on the distal surfaces. Similar results of greater attachment loss and radiographic alveolar bone loss were observed only at the distal sites of the experimental group. In addition, the increased radiographic bone loss was only found at the distal sites (adjacent to the surgical location) and not at the mesial sites (distant from the surgical location) on the experimental group. CONCLUSIONS: In this study, greater periodontal breakdown, including probing depth, attachment loss, and radiographic alveolar bone loss, was found at the distal sites, but not at the mesial sites, of the experimental molars where the third molar was surgically extracted compared with the control teeth (no surgery). In the experimental molars, more radiographic bone loss was found at the sites adjacent to the surgical location than at the sites distant to the surgical location. Therefore, we suggest that the surgical removal of the mandibular third molar may lead to a periodontal breakdown on the distal surface of the second molar. Periodontal re-evaluation after the initial healing of third molar extraction is indicated.