金属烤瓷全冠修复老年人活髓隐裂牙适应证及临床疗效

目的：探讨老年人活髓隐裂牙应用金属烤瓷全冠修复临床效果及适应症。方法：选取本院2006年1月至2011年1月期间收治的356例老年活髓隐裂牙合计621颗为研究对象,根据患牙疼痛程度随机将患者分为咬合疼痛组（A组）104例合计215颗患牙,咬合伴过敏性冷热刺激痛组（B组）122例合计232颗患牙,咬合伴延续性冷热刺激疼痛组（C组）130例合计174颗患牙,所有患者均接受金属烤瓷全冠修复,观察患者在治疗后1个月、6个月、12个月、18个月、24个月治愈情况以及牙髓及根尖周病变及牙髓发生情况。结果：与C组相比,A组、B组术后1个月、6个月、12个月、18个月、24个月治愈率以及总有效率较高,差异有统计学意义（P〈0．05）。结论：金属烤瓷全冠修复适合于轻微咬合疼痛以及咬合伴过敏性冷热刺激痛的患者,而对于咬舍伴延续性冷热刺激疼痛的患者则宜先行根管治疗术再进行全冠修复。     

放射直视影像在口腔固定修复中的临床应用评价

目的：探讨放射直视影像（radiovisiography,RVG）在口腔固定修复中的应用价值。方法：对拟行口腔固定修复中的全冠及桩核冠修复的患牙术前进行RVG投照,对RVG图像进行分析,分别测量牙冠各部位的厚度以及牙根的长度、角度、根管各部位的直径,从而对活髓牙牙体预备中并发症的预测和预防以及桩间隙制备时器械的选择和桩的设计。结果：67颗活髓牙中7例前牙需要术前进行根管治疗,1例术中发生针尖大小的穿髓点,予dycal垫底后保留活髓。因为术前及早的预测穿髓事件的发生,病人均满意及理解。拟行桩核冠修复的21颗患牙无一例发生根管侧穿,观察3月未发现有一例根折。结论：RVG能快速,经济,直观的给临床口腔修复医师提供牙体全面的信息,有利于并发症的预防及治疗方案的选择。     

冷光美白技术漂白活髓着色牙的临床疗效分析

目的：评价应用Beyond冷光美白技术漂白活髓着色牙的临床疗效。方法：选择牙齿变色病人117例,其中外源性染色牙18例,氟牙症16例,四环素染色牙47例,增龄性变色牙36例,该组病例的前牙及第一前磨牙均为活髓牙,采用Beyond冷光漂白法治疗,关白效果用Vita比色板进行前后比较。结果：外源性着色牙与增龄性变色牙关白疗效较好,平均提高6．09个色阶。对氟牙症疗效也较明显,但颜色分布不均匀,仍会有条纹或斑块状白斑。对轻、中度的四环素牙平均可提高3．46个色阶,重度四环素牙疗效欠佳。结论：Beyond冷光美白技术是目前治疗活髓变色牙特别简捷、安全和有效的方法之一。     

Er,Cr:YSGG激光处理正常及龋坏牙本质的扫描电镜观察

目的：利用扫描电镜观察Er,Cr：YSGG激光处理龋坏牙本质的形态学改变,并与常规方法进行比较。方法：将24颗新拔除的患龋牙随机分成2组,每组12颗牙。第1组常规处理组：分别用金刚砂石针、碳钢裂钻和挖器处理正常及龋坏牙本质;第2组激光处理组：分别用2WEr,Cr：YSGG激光、4WEr,Cr：YSGG激光处理正常及龋坏牙本质。常规制片,扫描电镜下观察。结果：与常规方法相比,激光处理后的牙本质表面不平,呈鱼鳞状、片状的粗糙外观;表面清洁,无玷污层,牙本质小管口清晰可见;4W激光作用时偶见微裂;激光处理后的牙本质表面具有增加树脂黏结性的形态学改变．结论：Er,Cr：YSGG激光能有效地清除龋坏牙本质及玷污层,并可使牙体组织发生一定的形态学改变。因此,Er,Cr：YSGG激光能够替代常规去龋备洞方法。     

脉冲Nd：YAG激光在根管预备中的临床应用

为了观察脉冲Ｎｄ：ＹＡＧ激光在根管预备（以下简称根备）中的作用,我们用Ｎｄ：ＹＡＧ激光辅助,以３０颗患牙进行根备,根备后即时根充。并与超声根备后即时根充、传统根备后即时根充比较,结果表明：激光组的术后疼痛反应少于超声组与传统组,远期疗效与超声组相仿,而优于传统组。     

聚合瓷嵌体修复活髓后牙大面积牙体缺损中的临床研究

目的:研究聚合瓷嵌体修复活髓后牙大面积牙体缺损(Big dentin defect,BDD)中的临床疗效。方法:从2009年6月到2011年6月,于我院牙科就诊病患中,后牙的牙体缺损大于1个牙尖者有80例,共87颗牙齿。以数字法随机分成治疗组(41例,46颗)及对照组(39例,43颗)。对照组以高嵌体方案治疗,治疗组以聚合瓷嵌体方案治疗。对比两组一周以及一年后修复体评价情况。结果:治疗一周后,治疗组在美观方面显著优于对照组,差异有统计学意义(u=2.038,P0.05)。而两组对比术后敏感以及牙周状况等数据,差异均无统计学意义(u=1.132,1.389,均P0.05)。治疗一年后,治疗组在修复体折裂以及美观等方面显著优于对照组。差异有统计学意义(u=3.138,2.874,均P0.05)。两组在继发龋和边缘着色,邻接以及肩台适合和牙周状况等方面对比,差异均无统计学意义(u=1.132,1.374,1.454,1.268,1.366,均P0.05)。结论:聚合瓷嵌体对于活髓后牙BDD的修复效果较为显著,可较大程度恢复病患牙体功能,减少继发龋的发生率。不易折裂又更加美观,值得临床推荐。     

脉冲Nd∶YAG激光在根管预备中的临床应用——与超声根管预备、传统手动根管预备比较

为了观察脉冲Ｎｄ∶ＹＡＧ激光在根管预备（以下简称根备）中的作用,我们用Ｎｄ∶ＹＡＧ激光辅助,对３０颗患牙进行根备,根备后即时根充。并与超声根备后即时根充、传统根备后即时根充比较,结果表明：激光组的术后疼痛反应少于超声组与传统组,远期疗效与超声组相仿,而优于传统组。     

冷光美白技术漂白活髓着色牙的临床疗效分析

目的:评价应用Beyond冷光美白技术漂白活髓着色牙的临床疗效。方法:选择牙齿变色病人117例,其中外源性染色牙18例,氟牙症16例,四环素染色牙47例,增龄性变色牙36例,该组病例的前牙及第一前磨牙均为活髓牙,采用Beyond冷光漂白法治疗,美白效果用Vita比色板进行前后比较。结果:外源性着色牙与增龄性变色牙美白疗效较好,平均提高6.09个色阶。对氟牙症疗效也较明显,但颜色分布不均匀,仍会有条纹或斑块状白斑。对轻、中度的四环素牙平均可提高3.46个色阶,重度四环素牙疗效欠佳。结论:Beyond冷光美白技术是目前治疗活髓变色牙特别简捷、安全和有效的方法之一。     

MTA、iRoot BP Plus及氢氧化钙在年轻恒牙活髓切断术中临床疗效的比较分析

摘要 目的：研究三氧化矿物凝聚体（MTA）、iRoot BP Plus（iRooT）以及氢氧化钙（Ca(OH) ₂）三种材料在年轻恒牙活髓切断术中的临床疗效。方法：将60例需要接受年轻恒牙活髓切断术的患者（60颗患牙）按照使用材料不同随机分为三组：MTA组、iRooT组和Ca（OH）₂组,每组20例（20颗患牙）,比较三组患者术后3个月和6个月手术成功率、牙本质桥形成和牙齿变色发生率、牙根管壁厚度、牙齿功能和美观度、以及血清基质金属蛋白酶-3（MMP-3）和白细胞介素-8（IL-8）水平。结果：（1）三组患者仅术后6个月临床治疗成功率存在显著差异（P<0.05）;（2）Ca（OH）₂组术后牙本质桥形成率显著低于其他两组（P<0.05）,而牙齿变色发生率显著低于MTA组（P<0.05）和显著高于iRooT组（P<0.05）。（3）三组患者治疗后牙根管壁厚度均较治疗前显著增加,且治疗后Ca（OH）₂组患牙根管壁厚度增加显著低于MTA组和iRooT组（P<0.05）。（4）Ca（OH）2组患者术后6个月牙齿舒适功能、固定功能和咀嚼功能评分均显著低于MTA组和iRooT组（P<0.05）,而牙齿美观度评分显著低于iRooT组（P<0.05）和显著高于MTA组（P<0.05）。（5）三组患者术后6个月血清MMP-3和IL-8均显著低于术前（P<0.05）,并且MTA组患者血清MMP-3和IL-8水平显著高于iRooT组（P<0.05）和显著低于CaOH组（P<0.05）。结论：iRoot BP Plus和MTA材料应用于年轻恒牙活髓切断术均具有较高的远期成功率,但MTA材料远期牙齿变色率较高因而影响牙齿美观度。     

Embrace树脂和LuxaCoreZ-Dual树脂在纤维桩全冠修复牙冠严重缺损的效果对比

目的:比较Embrace树脂和Luxa Core Z-Dual树脂在纤维桩全冠修复牙冠严重缺损的效果。方法:将116颗牙冠严重缺损的患牙行根管治疗后随机分为两组,A组60颗(前牙39颗,后牙21颗)采用Embrace树脂及纤维桩全冠修复。B组56颗(前牙33颗,后牙23颗)采用Luxa Core Z-Dual树脂及纤维全冠修复,比较两组患牙的修复效果。结果:对所有患者随访3-12月,A组58颗牙修复体完好,失败2颗,成功率为96.66%,其中前牙失败2颗,成功率为94.87%,而后牙成功率为100%;B组54颗牙修复体完好,2颗失败,成功率为96.43%,其中前牙失败2颗,成功率为93.94%,而后牙成功率为100%,两组患牙修复体成功率比较差异无统计学意义(P0.05),4颗修复体的失败均因纤维桩松动脱落所致。结论:Embrace树脂和Luxa Core Z-Dual树脂在纤维桩全冠修复牙冠严重缺损时均具有良好的临床疗效,但Embrace树脂临床操作上更简便。     

3D打印聚醚醚酮在先天性缺牙患者修复中的应用价值

目的:探讨3D打印聚醚醚酮在先天性缺牙患者修复中的应用价值。方法:2013年5月至2019年10月选择在本院诊治的先天性缺牙患者72例,根据随机数字表法把患者分为观察组与对照组各36例。对照组给予传统口腔修复治疗,观察组在对照组治疗的基础上给予3D打印聚醚醚酮修复治疗,记录与随访两组预后情况。结果:所有患者都顺利完成修复,治疗3个月观察组的总有效率为100.0%,显著高于对照组的88.9%(P<0.05)。两组治疗3个月的牙龈指数都低于治疗前,观察组也低于对照组(P<0.05)。治疗后3个月观察组的感染、刺激痛、出血、修复体脱落等并发症发生率为5.6%,显著低于对照组的27.8%(P<0.05)。治疗后3个月与4个月,观察组的美学评分都显著高于对照组(P<0.05)。结论:3D打印聚醚醚酮在先天性缺牙患者修复中的应用能够促进牙周清洁,减少并发症的发生,从而提高临床疗效与美学效果。     

Sexual dimorphism in modern human permanent teeth

On average, males possess larger tooth crowns than females in contemporary human populations, although the degree of dimorphism varies within different populations. In previous studies, different amounts of either enamel or dentine were implicated as the cause of this dimorphism. In this study, we attempt to determine the nature of sexual dimorphism in the crowns of permanent modern human teeth and to determine if two contrasting tooth types (permanent third molars and canines) show identical patterns of dimorphism in enamel and dentine distribution. We estimated the relative contributions of both enamel and dentine to total crown size, from buccolingual sections of teeth. Our sample consisted of a total of 144 mandibular permanent third molars and 25 permanent mandibular canines of known sex. We show that sexual dimorphism is likely due, in part, to the presence of relatively more dentine in the crowns of male teeth. However, whatever the underlying cause, dimorphism in both tooth root and tooth crown size should produce measurable dimorphism in tooth weight, though this has not been previously explored. Therefore, we provide some preliminary data that indicate the usefulness of wet tooth weight as a measure of sexual dimorphism. Both male permanent third molars and canines are significantly heavier than those of females. The weight dimorphism reported here for both classes of teeth may prove a useful finding for future forensic studies. In particular, weights of canines may be more useful as a means of sexing modern human skeletal material than linear or area measurements of teeth.     

The stress model of abutment tooth and periodontal tissues with unilateral mandibular dissociation and loss by precision extracoronal attachment

In order to explore the application of the precision extracoronal attachment based on three-dimensional finite element stress model in the repair of unilateral mandibular dissociation and loss, the stress distribution of the butment and periodontal tissues when the precision extracoronal attachment was used in unilateral mandibular dissociation and loss was analyzed, so as to provide reference for the application of materials in clinical repair. In this study, the biomechanics of oral cavity and its attachment were analyzed to provide theoretical basis for model construction. Because the degree of periodontal tissue absorption and the number of abutment teeth affected the restoration effect of the coronal precision attachment, the models were established from these two perspectives. The results showed that when the periodontal tissue absorption of both abutment teeth exceeded 1/3, the method of double abutment restoration was not recommended. When three abutments were used, there was a significant decrease compared with the absorption of the periodontal tissue of the double abutment. In clinic, the stress distribution of the distal abutment teeth and its periodontal tissues can be improved by increasing the number of abutment tooth. However, since increasing the number of abutments required an increase in the amount of healthy tooth tissue, it couldn’t be blindly selected in the clinic. After comprehensive consideration, it is appropriate to choose two abutment teeth for restoration.     

Developmental stage of the dentition and speech sound production in a series of first-grade schoolchildren.

This study was undertaken to investigate the effect of developmental stage of the dentition on speech sound production in children with and without articulatory speech disorders. In the whole sample, there were 281 subjects, mean age 7.5 years (SD 0.4). The stage of the eruption of the permanent incisors was calculated as the percentage height of each tooth of the mean crown height of the corresponding tooth in a group of 252 young adults. Eruptional stage of the first permanent molars was classified into three categories. Articulatory disorders were diagnosed by one experienced speech therapist and phoniatrician using the Remes Articulation Test [Remes, 1975] for the Finnish language. The results showed a wide interindividual variation in developmental stage of the dentition in a group of 7-year-old children with a tendency of the first permanent molars but not the incisors to erupt earlier in girls than in boys. Boys had a higher frequency of misarticulations estimated to need treatment than did girls. The present results indicate that during eruption of permanent teeth it is more important to draw attention to symmetrical eruption and to individual timing pattern rather than to the mean values of tooth eruption in subjects of the same age. The findings also suggest a decreasing risk of faulty speech sound production with advancing eruption of some permanent teeth still present in 7-year-old children.     

Horizontal tooth displacement and premolar occurrence in elephants and other elephantiform proboscideans

Abstract

Modern elephants lack permanent premolars and their cheek teeth succeed one another by an unusual horizontal tooth displacement mechanism. The fossil record demonstrates that this mechanism characterises elephantimorph proboscideans and first evolved in the late Oligocene. Horizontal tooth displacement provides elephantimorphs with an adaptive advantage over more primitive proboscideans with vertical tooth replacement and concurrent function of all adult teeth. Premolars were lost convergently in diverse elephantimorph taxa with small or no lower tusks and foreshortened symphyses, including independently in crown elephant genera. New evidence reveals the presence of premolars in early species of Loxodonta and loss of premolars in the Loxodonta clade by the mid-Pliocene. Rare occurrences of premolars in mammoths support the hypothesis that these teeth were lost by suppression of genetic and molecular processes responsible for their development. Retention of premolars in Elephas planifrons indicates independent loss of premolars in Elephas and mammoths, and that Elephas had multiple migrations out of Africa, once pre- and once post-loss of premolars in the genus. Unfortunately, the effects of dwarfing are thought to obscure the phylogenetic affinities of fossil elephants from Sulawesi and Java in the genus Stegoloxodon that retain permanent premolars.     

Mutations in AXIN2 cause familial tooth agenesis and predispose to colorectal cancer

Wnt signaling regulates embryonic pattern formation and morphogenesis of most organs. Aberrations of regulation of Wnt signaling may lead to cancer. Here, we have used positional cloning to identify the causative mutation in a Finnish family in which severe permanent tooth agenesis (oligodontia) and colorectal neoplasia segregate with dominant inheritance. Eleven members of the family lacked at least eight permanent teeth, two of whom developed only three permanent teeth. Colorectal cancer or precancerous lesions of variable types were found in eight of the patients with oligodontia. We show that oligodontia and predisposition to cancer are caused by a nonsense mutation, Arg656Stop, in the Wnt-signaling regulator AXIN2. In addition, we identified a de novo frameshift mutation 1994-1995insG in AXIN2 in an unrelated young patient with severe tooth agenesis. Both mutations are expected to activate Wnt signaling. The results provide the first evidence of the importance of Wnt signaling for the development of dentition in humans and suggest that an intricate control of Wnt-signal activity is necessary for normal tooth development, since both inhibition and stimulation of Wnt signaling may lead to tooth agenesis. Our findings introduce a new gene for hereditary colorectal cancer and suggest that tooth agenesis may be an indicator of cancer susceptibility.     

Carabelli's trait and tooth size of human maxillary first molars

Carabelli's trait is a morphological feature that can occur on the protocone of human maxillary molars. This study tests the hypothesis that Carabelli's trait is correlated statistically with the dimensions of the crown's four principal cusps or whether, as a cingular feature, the trait truly accretes onto an otherwise unaffected crown. Computer-assisted image analysis was used to measure the 6 intercusp distances and 12 angular relationships among cusp tips on the permanent first molar of 300 young adult American whites. Carabelli's complex was scored using an 8-grade ordinal scheme. Crown size was quantified in three ways, namely as 1) maximum mesiodistal and buccolingual diameters, 2) the 6 intercusp distances, and 3) the 12 angular cusp arrangements. There was no sex difference in the morphological expression of Carabelli's trait in this sample. Overall crown size and intercusp distances were significantly and progressively larger in molars with larger Carabelli's trait expressions. There are graded size responses between crown size (mesiodistal and buccolingual diameters), sizes of the four principal cusps, and morphological stage of Carabelli's complex, though the statistical relationships are appreciably stronger in males than females. Carabelli's trait occurs preferentially in larger molars. In contrast, angular (shape) relationships among cusp tips are not discernibly affected by trait size in either sex. There is the situation, then, that Carabelli's trait is developmentally correlated with crown size, but with no apparent alteration of cusp arrangements, suggesting that the increases are isometric across the occlusal table. Why the association is much weaker in females remains speculative, but these data provide yet another line of evidence that, within a population, tooth size is associated in a positive fashion with crown complexity.     

An experimental approach to modeling the strength of canine teeth

The strength of canine teeth in several carnivores is found through direct fracture experiments. The average forces required to break the canines of adult animals are coyote 1170 N, red fox 533 N, bobcat 737 N and raccoon 512 N. Stresses created in teeth at the breaking load are predicted by finite-element analysis and beam theory. The ultimate tensile stress sustainable in these teeth is 338 MPa in adult animals. The large pulp cavity in the canines of young animals significantly weakens the bases of their teeth (by about 25%), but as the animal ages the pulp cavity decreases and has little effect on overall tooth strength. The tooth material of young of the year is significantly weaker than that from older animals (by about 35%). With the experimentally derived ultimate tensile stress, finite-element analysis can estimate the breaking load of canines for several carnivores. A significant allometric relationship exists between log of body weight and log of strength of tooth (slope=0.81).