Postoperative Weight Loss Masks Metabolic Impacts of Periodontitis in Obese Rodents

Background: Postoperative weight loss (POWL) is expected to occur in combined models of obesity and periodontitis. This study explores the confounding effects of POWL on the impact of ligation‐induced periodontitis on glucose and lipid metabolism in obese animals. Methods: Combined mouse models of diet‐induced obesity (DIO) and ligation‐induced periodontitis (5‐ or 10‐day ligation) were studied. Fasting serum glucose (FSG), fasting insulin (Fins), and lipids including triglyceride (TG), total cholesterol (TC), and low‐ and high‐density lipoprotein cholesterol (HDLC), were detected via biochemistry and enzyme‐linked immunosorbent assay. POWL and homeostasis model assessment of insulin resistance (HOMA‐IR) were calculated. Analysis of covariance was performed to identify confounding effects of POWL. Results: The obesity, periodontitis, and 10‐day groups exhibited greater POWL than corresponding controls (P <0.01). Without considering POWL, conflicting results were found, including: 1) contradictory changes in HDLC caused by obesity or periodontitis; and 2) unequal levels of FSG, TC, and HDLC between days 5 and 10 in the sham‐ligation controls. Moreover, upregulating effects of periodontitis were found only on TG in the DIO mice, whereas those on Fins, HOMA‐IR, and HDLC were statistically veiled. After the confounding effects of POWL were filtered, periodontitis promoted increased levels of not only TG but also Fins, HOMA‐IR, and HDLC in the DIO mice (P <0.05). Conclusions: When analyzing the interrelationship between obesity and periodontitis, the confounding effects of an imbalanced POWL should be considered. Otherwise, impact of periodontitis on metabolic dysregulation in obese animals may be underestimated.     

Effect of obesity on alveolar bone loss in experimental periodontitis in Wistar rats

Obesity has been linked to higher inflammatory status and periodontal breakdown.

Objective

The purpose of this study was to investigate the effect of obesity on alveolar bone loss in experimental periodontitis in rats.

Material and Methods

Twenty-four female Wistar rats were randomly divided into two groups: obese (n=13), which were fed with "cafeteria diet" (CAF diet - high amounts of sucrose and fat) for 90 days in order to gain weight, and non-obese (n=11) regularly fed rats. Ligature-induced experimental periodontitis was created in all animals. Body weight differed statistically between obese and non-obese groups (277.59 and 223.35 g, respectively) at the moment of the ligature placement. Morphometric registration of alveolar bone loss was carried out after 30 days of ligature placement to determine the effect of obesity on the progression of experimental periodontitis.

Results

Intra-group comparisons showed significantly higher alveolar bone loss mean values in maxillary teeth with ligature (P<0.05). Alveolar bone loss [mean (SD), mm] was not statistically different between obese and non-obese groups [0.71 (0.09) and 0.65 (0.07) mm, respectively]. However, when palatal sides are analyzed separately, obese group presented significantly higher alveolar bone loss (P<0.05) as compared to non-obese [0.68 (0.12) and 0.53 (0.13) mm, respectively].

Conclusions

In spite of the weak differences, it is possible to conclude that the progression of alveolar bone loss in ligature-induced periodontitis can be potentially influenced by body weight in rats.     

Obesity and Hyperlipidemia Modulate Alveolar Bone Loss in Wistar Rats

Background: A positive association between obesity‐associated metabolic disorders (e.g., hyperlipidemia and diabetes) and periodontitis has been demonstrated in the literature. This study evaluates the role of cafeteria diet–induced obesity/hyperlipidemia (CAF) on alveolar bone loss (ABL) in rats. Methods: Sixty male Wistar rats were randomly divided in four groups: control, periodontitis (PERIO), obesity/hyperlipidemia (CAF), and obesity/hyperlipidemia plus periodontitis (CAF+PERIO). Groups CAF and CAF+PERIO were exposed to a high‐fat, hypercaloric diet. At week 12, periodontal disease was induced in groups PERIO and CAF+PERIO by ligatures in the upper second molar. The contralateral tooth was considered the intragroup control. Body weight and Lee index were evaluated weekly during the experiment. Serum glucose and cholesterol/triglycerides in the liver were evaluated, and percentage of ABL was measured by microcomputed tomography. Serum tumor necrosis factor (TNF)‐α and interleukin (IL)‐1β were evaluated by enzyme‐linked immunosorbent assay at week 17. Results: Body weight, Lee index, and cholesterol/triglycerides in the liver increased in groups exposed to the cafeteria diet. Groups PERIO and CAF+PERIO exhibited a significantly higher ABL compared to control and CAF groups. The presence of obesity and hyperlipidemia significantly increased ABL in the CAF+PERIO group compared to the PERIO group (53.60 ± 3.44 versus 42.78 ± 7.27, respectively) in the sides with ligature. Groups exposed to CAF exhibited higher ABL in the sides without ligature. No differences were observed among groups for IL‐1β and TNF‐α. Conclusion: Obesity and hyperlipidemia modulate the host response to challenges in the periodontium, increasing the expression of periodontal breakdown.     

高脂软饲料增加肥胖复合牙周炎小鼠模型的丝线松脱率

目的：探索高脂饲料对肥胖复合结扎诱导牙周炎模型的丝线稳定性的影响。方法：将134只小鼠分为高脂（HFD,n = 77）和低脂饲料（LFD,n = 57）组,分别诱导肥胖和作正常体重对照。诱导8、16、30周时,一次性丝线结扎5 d或10天d诱导牙周炎。分析饲料类型、饲料诱导期、牙周结扎期对丝线松脱的效应。结果： 丝线总体松脱率为6.0%,10天d（8.0%）比5天d（2.5%）高2倍（P < 0.01）,HFD（9.1%）比LFD（1.8%）高4倍（P < 0.05）。饲料诱导期对松脱率无显著影响。结论： 建立饮食诱导型肥胖与丝线结扎诱导牙周炎的复合模型时,高脂软饲料可明显增加丝线松脱率。为调和保护肥胖状态与结扎期延长致丝线松脱率增加的矛盾,结扎10天时结束诱导或更换丝线是合适的时间节点。     

Nafamostat mesilate,a potent tryptase inhibitor,modulates periodontitis in rats

Previous reports have demonstrated increased tryptase-like proteolytic activity in the crevicular fluid of patients with periodontal disease. In the present study, we have investigated the effect of tryptase inhibition with nafamostat mesilate (NM, 6-amino-2-naphtlyl p-guanidinobenzoate dimethansulfonate) on the development of experimental periodontitis in rats. Eighty (80) male Wistar rats were randomly separated into four groups: Control group, NM group (daily 0.1 mg/kg body weight of NM, i.p.), Ligature group (ligature placed at lower right first molars), and NM+Ligature group. The amount of alveolar bone loss (ABL) around the mesial root surface of the first mandibulary molar, as well as the myeloperoxidase (MPO) activity, and total proteolytic activity [N-benzoyl-l-arginine-p-nitroanilide (BApNA) substrate] were determined at 7 and 14 days. NM led to significantly (p < 0.05) decreased ABL in animals subjected to ligature-induced periodontitis. Tryptase inhibition prevented the onset of significant ABL at 7 days of experiment (0.44 ± 0.16 and 0.60 ± 0.22, p > 0.05, NM+Ligature and Control, respectively) and significantly decreased the ABL at 14 days (0.97 ± 0.17 versus 1.82 ± 0.26, p < 0.001, NM+Ligature versus Ligature, respectively). In addition, NM significantly decreased MPO and total proteolytic activity at 14 days (p < 0.05). These data provided evidence that tryptase inhibition with NM attenuates gingival granulocyte infiltration and ABL in an experimental model of periodontitis in rats.     

补肾坚骨汤对牙周炎大鼠细胞因子及牙周组织影响的研究

目的：通过检测牙周炎大鼠血清中白细胞介素-4(interleukin-4,IL-4)、白细胞介素-6(interleukin-6, IL-6)和肿瘤坏死因子-α(tumor necrosis factor-α, TNF-α)水平的变化,及牙周组织的形态改变,初步探讨补肾坚骨汤对牙周炎大鼠的治疗作用。方法雄性12月龄SD大鼠45只,其中8只为正常对照组,37只采用丝线结扎8周,建立大鼠牙周炎模型后,将建模成功大鼠(34只)随机分为牙周炎模型对照组10只,补肾坚骨汤高剂量组(16g/kg/d)8只,补肾坚骨汤中剂量组(8g/kg/d)8只,和补肾坚骨汤低剂量组(4g/kg/d)8只,给予补肾坚骨汤灌胃4周。各组大鼠末次给药后24 h处死,采用ELISA法检测外周血IL-4、IL-6和TNF-α的水平;取上颌骨制作牙体牙周组织联合切片,HE染色,光学显微镜下观察牙周的组织学改变。结果牙周炎模型对照组血清IL-6、TNF-α水平显著高于正常对照组,IL-4水平显著低于正常对照组。补肾坚骨汤各剂量治疗组血清IL-6、TNF-α水平显著低于牙周炎模型对照组,补肾坚骨汤高、中剂量治疗组血清IL-4水平显著高于牙周炎模型对照组(p<0．05)。牙周炎模型对照组牙周组织表现为明显的炎症破坏,牙槽骨吸收明显,而补肾坚骨汤高、中剂量治疗组牙周组织炎症均明显减轻,牙槽骨吸收减少且骨修复反应明显。结论补肾坚骨汤可能通过降低牙周炎大鼠血清中IL-6和TNF-α水平,升高IL-4水平,减轻牙周组织炎症,减缓牙周组织破坏。     

补肾坚骨汤对牙周炎大鼠血清白细胞介素-6和骨钙素影响的实验研究

目的：通过检测牙周炎大鼠血清中白细胞介素-6（interleukin-6/IL-6）和骨钙素（O steocalcin/OC）水平的变化,观察光学显微镜下牙周组织的形态改变,探讨补肾坚骨汤对牙周炎大鼠的治疗作用及可能机制。方法：雄性12月龄SD大鼠24只,8只为正常对照组（N）,其余成功建立大鼠牙周炎模型之后,分为牙周炎模型对照组（D）、补肾坚骨汤治疗组16g/（kg·d）（H）,给予补肾坚骨汤灌胃4周,每日一次,每次5m L,各组大鼠末次给药后24 h处死,摘取上颌骨制作牙体牙周组织联合切片,H E染色,在光学显微镜下观察牙周的组织学改变;采用ELISA法检测外周血IL-6和OC的水平。结果：牙周炎模型对照组牙周组织表现为明显的炎症破坏,牙槽骨吸收明显,而补肾坚骨汤治疗组牙周组织炎症明显减轻,牙槽骨吸收减少且骨修复反应明显;牙周炎模型对照组血清IL-6水平显著高于正常对照组和补肾坚骨汤治疗组（P〈0.05）;牙周炎模型对照组血清OC水平显著低于正常对照组和补肾坚骨汤治疗组（P〈0.05）。结论：补肾坚骨汤可能通过降低牙周炎大鼠血清中IL-6水平,升高OC水平,减轻牙周组织炎症,促进牙周组织再生,其作用机制还需进一步深入研究。     

Long‐term testosterone depletion attenuates inflammatory bone resorption in the ligature‐induced periodontal disease model

1 Background

Testosterone is known to affect bone in physiological and pathological conditions. The purpose of this study is to evaluate the role of testosterone in experimental periodontal disease in rats.

2 Methods

In this study we used a ligature model of periodontal disease in rats submitted to orchiectomy (OCX, testosterone depletion) with and without testosterone replacement therapy (TR). Control animals were sham‐operated and retained physiological testosterone levels. Sixty‐two days after orchiectomy and sham operations, ligatures were placed around the lower first molars for 2 weeks to induce experimental periodontal disease. Negative control animals received no ligatures. The outcomes assessed in the periodontal tissues were: inflammatory cytokine expression by enzyme‐linked immunosorbent assay (ELISA), stereometric analysis of the inflammatory process and quantitation of inflammatory bone resorption by microcomputed tomography (μ‐CT).

3 Results

The OCX+TR group showed the greatest increase in fibroblastic cells and blood vessels with reduced inflammatory cell numbers in the gingival tissue with induction of periodontal disease. There were no significant differences between OCX and Sham‐operated groups in all the stereometric parameters assessed. Ligature placement induced inflammatory bone resorption, which was significantly attenuated in OCX animals. Experimental periodontitis induced a significant increase in interleukin (IL)‐1β, but the lowest levels were observed in the periodontitis/OCX group. IL‐6 levels were not affected by OCX, but were significantly reduced in OCX+TR animals.

4 Conclusion

The findings of the present study suggest that testosterone depletion attenuates inflammatory bone resorption in ligature‐induced periodontitis, which may be partly mediated via decreased production of IL‐1β.     

2种给药方式下辛伐他汀对牙周炎骨质疏松大鼠上颌骨骨丢失的影响

目的比较辛伐他汀(Simvastatin,SIM)在不同给药方式下抑制牙周炎骨质疏松大鼠上颌骨骨丢失的作用效果。方法 24只4月龄雌性SD(Sprague Dawley)大鼠,随机分成4组:假手术组(SHAM),去势+绑线组(OVX+LIG),去势+绑线+辛伐他汀灌胃给药组(OVX+LIG+Oral SIM),去势+绑线+辛伐他汀局部用药组(OVX+LIG+Local SIM)。适应性喂养1周后,进行骨质疏松造模手术——双侧卵巢切除术(OVX),4周后,进行牙周炎造模手术——分别于双侧上颌骨第一、第二磨牙进行8字结扎绑线术(LIG),4周后拆除绑线,用药组开始辛伐他汀给药。8周后处死所有大鼠,收集双侧上颌骨和血清,分别进行进一步检测。检测包括micro-CT扫描,硬组织切片观察、染色,酶联免疫吸附实验(ELISA)。结果相比于对照OVX+LIG组,OVX+LIG+Local SIM组可见明显釉牙骨质界-牙槽嵴顶(CEJ-ABC)距离的减少(P<0.05),OVX+LIG+Oral SIM组与OVX+LIG+Local SIM组可见明显牙槽骨的骨密度(BMD)和骨体积分数(BVF)升高,OVX+LIG+Oral SIM组可见明显骨钙素(OC)上升,抗酒石酸酸性磷酸酶5b(TRAP5b)下降。结论局部或全身系统应用辛伐他汀能减缓牙周炎伴骨质疏松大鼠上颌骨的骨丢失,其中局部注射辛伐他汀对牙槽嵴顶骨形成具有促进作用。     

不同结扎方法对失神经支配大鼠牙周炎的影响

目的：比较牙颈部丝线结扎＋高糖饮食、正畸结扎丝结扎＋高糖饮食对失下牙槽神经支配下大鼠牙周炎进展的影响。方法：将80只2月龄SPF级Wistar雄性大鼠随机分为5组：离断下牙槽神经＋丝线结扎下颌第一磨牙＋高糖饮食组（P1组）;离断下牙槽神经＋正畸结扎丝结扎下颌第一磨牙＋高糖饮食组（P2组）;单纯诱导牙周炎组（P3组）;单纯离断下牙槽神经组（P4组）;假手术组（N组）。分别在1周、2周、4周、6周取标本,进行临床指标观察和组织学观察。结果： P4组和N组未见牙周炎表现, P1、 P2、 P3组均出现牙周炎, P1组较P2、 P3组牙周损害出现早且严重。结论：丝线结扎下颌第一磨牙＋高糖饮食更容易诱导失神经支配的大鼠形成牙周炎。     

牙周治疗前后血清抗体滴度及亲和性的变化

目的 观察牙周治疗前后抗牙龈卟啉菌（Ｐｇ）抗体滴度及亲和性的变化,探讨其在牙周炎致病机制中的作用。方法 采用ＥＬＩＳＡ法,检测１７例牙周炎患者治疗前及治疗后１个月及６名健康对照者的血清抗Ｐｇ３８１ＩｇＧ抗体滴度及亲和性。结果 牙周炎组治疗前抗体滴度高于对照组（Ｐ〈０．００１）,抗体滴度与探诊深度有负相关趋势,治疗后滴度显著降低（Ｐ〈０．０１）;亲和性与对照组间差异无显著性,治疗后也无显著性差异。     

Influence of periodontitis and scaling and root planing on insulin resistance and hepatic CD36 in obese rats

1 Background

The aim of the study was to explore the influence of periodontitis and scaling and root planing (SRP) on insulin resistance and hepatic CD36 in obese rats with periodontitis.

2 Methods

Thirty‐two specific pathogen free Sprague‐Dawley rats were randomly divided into four groups of eight animals each as follows: healthy rats (healthy group), obese rats (obesity group), obese rats with periodontitis (non‐therapy group), and obese rats with periodontitis who underwent periodontal SRP (therapy group). Rats were fed with a high‐fat diet for 16 weeks to build an obesity model. Periodontal inflammation was induced by performing periodontal ligation with Porphyromonas gingivalis. The tissue around the maxillary second molars, bilaterally, were collected. The periodontal attachment level (from the cemento‐enamel junction to the bottom of the periodontal pocket) of the second molars was measured in all groups. All rats were subjected to fasting blood glucose, insulin, and serum C‐reactive protein tests (CRP). Insulin resistance was evaluated by homeostasis model assessment of insulin resistance (HOMA‐IR), oral glucose tolerance test (OGTT), and area under the curve (AUC). The liver was excised to detect intrahepatic free fatty acid (FFA) levels and pathologic observation. Real‐time quantification PCR, western blot, and immunohistochemistry were applied to detect hepatic CD36 expression.

3 Results

Compared with the obesity group, HOMA‐IR, AUC, intrahepatic FFA, and protein expression, and mRNA levels of hepatic CD36 in the non‐therapy group were significantly increased (P < 0.05). HOMA‐IR, AUC, CRP, protein expression, and mRNA levels of hepatic CD36 were all significantly decreased (P < 0.05) 2‐weeks after SRP.

4 Conclusions

Periodontitis increases insulin resistance while scaling and root planning could improve insulin resistance. Hepatic CD36 regulation may be considered a potential mechanism for this phenomenon.     

肥胖伴牙周感染小鼠体内B-1a细胞的表达初探

目的:分析肥胖伴牙周感染小鼠体内B-1a细胞的表达变化.方法:建立饮食诱导型肥胖伴实验性牙周感染的小鼠模型,通过免疫组化和蛋白质印迹的方法检测小鼠颌骨和脾脏中CD5、抗Ⅰ型胶原(Col-Ⅰ)抗体、IL-10的蛋白表达量;实时定量PCR检测小鼠颌骨中CD5、抗Col-Ⅰ抗体、IL-10 的mRNA表达量.结果:牙周炎组颌骨中的CD5、IL-10、抗Col-Ⅰ抗体的蛋白和mRNA表达量均显著高于对照组(P<0.001);肥胖组脾脏中的CD5、IL-10、抗Col-Ⅰ抗体的蛋白表达量显著高于标准组(P<0.05);标准伴牙周真性结扎组脾脏中抗Col-Ⅰ抗体的表达量显著高于标准伴牙周假性结扎组(P<0.05).结论:B-1a细胞在肥胖与牙周炎的炎症早期被激活并存在一定的病理意义,这两种炎症状态并没有在病理机制上出现交叉影响.     

Experimental periodontitis promotes transient vascular inflammation and endothelial dysfunction

Objectives

This study aimed to evaluate the systemic inflammatory response and cardiovascular changes induced by experimental periodontitis in rats.

Design

Experimental periodontitis was induced by placing a cotton ligature around the cervix of both sides of mandibular first molars and maxillary second molars in each male rat. Sham-operated rats had the ligature removed immediately after the procedure. Seven, 14 or 28 days after procedure, the effects of acetylcholine, sodium nitroprusside and phenylephrine were evaluated on blood pressure, aortic rings and isolated and perfused mesenteric bed. The blood was obtained for plasma Interleukin-6 (IL-6), C-reactive protein (CRP) and lipid evaluation. The mesenteric vessels were obtained to evaluate superoxide production and nitric oxide synthase 3 (NOS-3) expression.

Results

Ligature induced periodontitis reduced endothelium-dependent vasodilatation, a hallmark of endothelial dysfunction. This effect was associated with an increase in systemic inflammatory markers (IL-6 and CRP), worsens on lipid profile, increased vascular superoxide production and reduced NOS-3 expression. It is interesting to note that many of these effects were transitory.

Conclusion

Periodontitis induced a transient systemic and vascular inflammation which leads to endothelial dysfunction, an initial step for cardiovascular diseases. Moreover, the animal model of periodontitis used here may represent a valuable tool for studying the relationship between periodontitis and endothelial dysfunction.     

实验性牙周炎对肥胖大鼠血清C反应蛋白及胰岛素抵抗的影响

目的:探讨实验性牙周炎对肥胖大鼠血清C反应蛋白(CRP)及胰岛素抵抗指数(HOMA-IR)随时间的变化.方法:4 周龄SD大鼠(n=35)高脂饲料喂养16 周建立肥胖模型.按肥胖指标筛除5 只,其余30 只肥胖大鼠按1:2比例,随机选取10 只大鼠为肥胖组,20 只肥胖大鼠牙周丝线结扎建立肥胖复合牙周炎模型(复合组),结扎后有4 只大鼠死亡.在牙周结扎前、结扎1 周、4 周3 个时间点眼眶静脉取血,检测空腹血糖及空腹胰岛素,并计算HOMA-IR及β细胞功能指数(HOMA-β);ELISA检测血清CRP水平.结果:牙周结扎1 周后,复合组CRP水平显著升高,在结扎4 周时则逐渐回落(F=7.773,P=0.004).牙周结扎后4 周,复合组HOMA-IR显著高于肥胖组(F=-4.691,P=0.000),HOMA-β显著低于对照组(F=3.672,P=0.002).结论:实验性牙周炎影响肥胖大鼠血清CRP水平;实验性牙周炎会加重肥胖大鼠的胰岛素抵抗状态并下调β细胞功能.     

慢性不可预知性应激对大鼠实验性牙周炎预后的影响

目的:探讨慢性不可预知性复合心理应激对大鼠实验性牙周炎模型牙周组织愈合的影响。方法:雄性SD大鼠128只,随机抽取32只作为正常对照组。其余96只大鼠用丝线结扎右上颌第二磨牙颈部,4周后,采用龈沟出血指数和牙周探诊深度验证牙周炎模型。同时将大鼠结扎丝线去除,随机分为牙周炎对照组、牙周炎+应激组、牙周炎+应激+应激对抗药物组,每组32只。实验第5周起,应激组和药物组大鼠每日给予慢性不可预知性应激,同时药物组每日按5 mg/kg腹腔注射氟西汀。于实验第4、5、6、8周进行大鼠体质量测量、行为学测试、血清学检测;采用组织学观察牙周组织炎症反应、牙槽骨丧失、附着丧失以及破骨细胞计数。结果:心理应激大鼠出现体质量增长减慢、行为异常、血清皮质酮与促肾上腺皮质激素浓度升高(P<0.05),心理应激影响下大鼠牙周炎的愈合进程减慢,炎细胞浸润面积、牙槽骨吸收量与破骨细胞计数在实验第6周和8周、附着丧失在第8周高于对照组(P<0.05)。抗应激药物可逆转心理应激对牙周炎愈合过程的影响,该组炎细胞浸润面积与牙槽骨吸收在第6周和8周、破骨细胞计数在第8周明显低于应激组(P<0.05)。结论:慢性不可预知性心理应激能影响牙周组织的愈合,影响牙周炎的预后。而药物对抗应激能够减轻这种影响。     

Effects of Polycan,a β‐glucan,on experimental periodontitis and alveolar bone loss in Sprague‐Dawley rats

Kim YS, Kang SJ, Kim JW, Cho HR, Moon SB, Kim KY, Lee HS, Han CH, Ku SK, Lee YJ. Effects of Polycan, a β‐glucan, on experimental periodontitis and alveolar bone loss in Sprague‐Dawley rats. J Periodont Res 2012; 47: 800–810. © 2012 John Wiley & Sons A/S Background and Objective: Polycan is a promising candidate for the treatment of periodontal disease. This study was undertaken to examine whether Polycan, a type of β‐glucan, has a protective effect on ligature‐induced experimental periodontitis and related alveolar bone loss in Sprague‐Dawley rats. Material and Methods: Polycan was orally administered, daily, for 10 d, at 21.25, 42.5 or 85 mg/kg, beginning 1 d after ligation. Changes in body weight and alveolar bone loss were monitored, and the anti‐inflammatory effects of Polycan were determined by measuring the levels of myeloperoxidase (MPO), interleukin‐1beta (IL‐1β) and tumor necrosis factor‐alpha (TNF‐α) in gingival tissue. We also evaluated inducible nitric oxide synthase (iNOS) activity and malondialdehyde (MDA) concentrations as a measure of the antioxidant effect. Results: Ligature placement led to a marked decrease in body weight, increased alveolar bone loss and increased concentrations of MPO, IL‐1β, TNF‐α and MDA, as well as increased iNOS activity and inflammatory cell infiltration and decreased collagen‐fiber content. Histological examination revealed increases in the number and activity of osteoclast cells, decreases in alveolar bone volume and elevated percentages of osteclasts on the alveolar bone surface. Daily oral treatment with 42.5 or 85 mg/kg of Polycan for 10 d led to significant, dose‐dependent inhibition of the effect of ligature placement. Conclusion: Taken together, these results suggest that 10 d of oral treatment with Polycan effectively inhibits ligature placement‐induced periodontitis and related alveolar bone loss via an antioxidant effect.     

Inflammatory responses in two commonly used rat models for experimental tooth movement: comparison with ligature-induced periodontitis

Objective

To compare two often used rat models for experimental tooth movement, namely the elastic band, and the coil spring model. They were compared with a silk-ligature-induced periodontitis model.

Design

Thirty six, 6-weeks-old rats were used. In a split mouth design four experimental conditions were allocated by permutation: (1) insertion of an orthodontic elastic band between the maxillary first and the second molar, (2) placement of a silk ligature around the cervix of the upper second molar, (3) a 10 cN NiTi coil spring for mesial movement of the three maxillary molars as one block, and (4) Control. After 1, 3, and 5 days, rats were killed and immunohistochemical staining for ED1, cathepsin K, and MMP9 was performed.

Results

A time-dependent increase in the inflammatory infiltration of the interdental papilla was found in the elastic band and the ligature model, but not in the spring model. The disruption of the epithelium of the interdental papilla and the transseptal fibers was less severe in the spring group than in the other two experimental groups. All three experimental groups showed a time-dependent resorption of the interdental bony septum. However, this started faster and was more severe in the elastic band and the ligature than in the spring group. The numbers of cathepsin K+ and MMP9+ cells were higher in the elastic band and the ligature group than in the spring group.

Conclusions

Elastic bands yield similar periodontal effects as ligatures. The spring model is to be preferred for experimental tooth movement studies.     

Molecular imaging assessment of periodontitis lesions in an experimental mouse model

Clinical Oral Investigations - We aimed to evaluate molecular imaging as a novel diagnostic tool for mice periodontitis model induced by ligature and Porphyromonas gingivalis (Pg) inoculation....     

Clinical and microbiological evaluation of ligature-induced peri-implantitis and periodontitis in dogs

The purpose of this study was to evaluate the attachment loss around teeth and implants by clinical and microbiological analysis. The mandibular premolars were extracted in 5 mongrel dogs and, 3 months later, two titanium implants were installed on each side of the mandible and, after another 3 months, abutment connection was performed. Plaque control in the implants and maxillary premolars was maintained for two weeks prior to the start of the main experiment. On day 0 and 30 days after ligature placement, microbiological samples were obtained and relative attachment level was measured for the teeth and implants. The presence of Porphyromonas gingivalis, Bacteroides forsythus, Actinobacillus actinomycetemcomitans, Prevotella intermedia and Prevotella nigrescens was evaluated by polymerase chain reaction technique on day 0 and 30 days after ligature placement. None of the above bacteria were detected on day 0. Thirty days after ligature placement, P. gingivalis was present in 95% and 85% and B. forsythus was present in 80% and 85% of the implants and teeth sites, respectively. Statistical analysis (one-way RM-ANOVA) showed a significant difference (P<0.01) between pre- and post-induction measurements around teeth and implants. However, there was no significant difference (P=0.41) in the rate of attachment loss, between periodontitis and peri-implantitis. It can be concluded that: (1) P. gingivalis and B. forsythus were strongly associated with induced peri-implantitis and periodontitis, and (2) induced peri-implantitis and periodontitis presented a similar rate of attachment loss.