应用锥形束CT和根尖片评估工作长度对根管治疗疗效的影响

目的： 应用锥形束CT（cone-beam computed tomography, CBCT）和根尖片研究工作长度对根管治疗疗效的影响。方法：利用CBCT和根尖片评估503个做过根管充填的牙根管。依据影像学上的根尖孔点和充填材料末端的距离将其分为4组,分别是：①大于1 mm、小于2 mm;②小于1 mm;③超出根尖孔;④恰到根尖孔。采用SPSS13.0软件包对数据进行χ²检验。结果：在前牙、前磨牙和磨牙的根管治疗中,根管充填距离根尖孔1~2 mm,根尖片显示分别占88%、89.3%和95%;CBCT显示的结果则分别是70%、73.7%和79%。无论哪一种诊断方法,磨牙出现根尖周炎的概率均显著高于其他牙。结论：各种工作长度的根管充填都能检测到根尖周炎,应用CBCT进行检查,能更好地评估根管治疗疗效。     

下颌第一前磨牙C形牙根根管横断面形态及壁厚的锥体束CT分析

目的:分析下颌第一前磨牙C形牙根的根管横断面形态,并对最小根管壁厚度进行测量.方法:选取44颗具有C形牙根的下颌第一前磨牙,使用锥体束CT(cone-beam computed tomography,CBCT)进行扫描,并三维重建.分析根颈1/3、根中1/3和根尖1/3段的根管横断面形态分布变化,并对牙根各段的根面沟侧及对侧最小根管壁厚度进行测量比较.采用SPSS13.0软件包对数据进行统计学分析.结果:根中1/3、根尖1/3的根管横断面形态分布较为复杂,以C2～C4型为主,与根颈1/3存在显著差异(P＜0.05);根中 1/3和根尖1/3根面沟侧的最小根管壁厚度小于对侧(P＜0.05),且最小根管壁厚度均＜1mm.结论:下颌第一前磨牙C形牙根的中下段根管形态复杂,且根面沟侧的根管壁较薄,临床治疗中应考虑到以上解剖特点.     

Influence of hemostatic agents upon the outcome of periapical surgery: Dressings with anesthetic and vasoconstrictor or aluminum chloride

Objective: To evaluate the effects of different hemostatic agents upon the outcome of periapical surgery. Design: A retrospective study was made of patients subjected to periapical surgery between 2006-2009 with the ultrasound technique and using MTA as retrograde filler material. We included patients with a minimum follow-up of 12 months, divided into two groups according to the hemostatic agent used: A) dressings impregnated in anesthetic solution with adrenalin; or B) aluminum chloride paste (Expasyl™). Radiological controls were made after 6 and 12 months, and on the last visit. The global evolution scale proposed by von Arx and Kurt (1999) was used to establish the outcome of periapical surgery.Results: A total of 96 patients (42 males and 54 females) with a mean age of 40.7 years were included. There were 50 patients in the aluminum chloride group and 46 patients in the anesthetic solution with vasoconstrictor group. No significant differences were observed between the two groups in terms of outcome after 12 months - the success rate being 58.6% and 61.7% in the anesthetic solution with vasoconstrictor and aluminum chloride groups, respectively (p>0.05).Conclusion: The outcome after 12 months of follow-up was better in the aluminum chloride group than in the anesthetic solution with vasoconstrictor group, though the difference was not significant. Key words:Aluminum chloride, bleeding control, hemostasis, periapical surgery, outcome.     

Influence of cement thickness and mechanical cycling on the push-out bond strength between posts and root dentin

The aim of this study was to assess the influence of mechanical cycling and cement thickness on the bond strength between fiber posts and root dentin. Forty bovine teeth were sectioned (16 mm) and randomly assigned to four groups (n = 10). Specimens in Groups 1 and 2 were cemented using a thinner cement layer, while specimens in Groups 3 and 4 were cemented using a thicker cement layer. Groups 2 and 4 were submitted to mechanical cycling. Four slices per specimen were produced and submitted to push-out testing. Bond strength values were not affected by mechanical cycling (P = 0.2893), although the thickness of the cement layer did affect bond strengths (P = 0.0059, thinner > thicker). Tukey's test showed that Group 1 (19.27 MPa) had a higher mean bond strength value than Group 3 (12.4 MPa) and Group 4 (13.6 MPa), while Group 2 (15.0 MPa) was statistically similar to all groups. These results indicate that a thicker cement layer negatively affected the push-out bond strength between a fiber post and root dentin, regardless of whether the specimens were subjected to mechanical cycling.     

Apical surgery vs apical surgery with simultaneous orthograde retreatment: A prospective cohort clinical study of teeth affected by persistent periapical lesion

Aim

This prospective clinical study analyzed the 24-month outcome of conventional apical surgery retro-filled with calcium-silicate cement versus apical surgery with simultaneous orthograde retreatment by means of clinical and radiographic criteria.

Influence of cement thickness on the bond strength of tooth-colored posts to root dentin after thermal cycling

Abstract

Objective. The purpose of this study was to evaluate the effect of different resin cement thickness on the push-out bond strength of different posts (CAD/CAM zirconia post (ZR post)) and an individually formed glass fiber reinforced composite post (IPN post) prior to and after thermal cycling (TC). Methods. Post spaces with a height of 9 mm and a diameter of 1.5 mm were drilled in 80 mandibular premolar teeth. Two groups (n = 40) were formed according to the posts used (IPN posts or ZR posts). Then the specimens were randomly assigned into two sub-groups according to the post diameter: (1) 1.5 mm in diameter and (2) 1.2 mm in diameter (n = 20/per group). All posts were luted with a self-adhesive luting agent according to the manufacturer's instructions by using endo tips. Half of the samples (n = 10) were submitted to thermal cycling (5000 cycles, 5–55°C). Thereafter, four 2-mm thick horizontal sections were obtained and subjected to push-out test. Failure modes were assessed quantitatively and morphologically. The data were statistically analyzed with a three-way analysis of variance (ANOVA) (p < 0.05). Statistical differences in failure modes were investigated by chi-square tests at a significance level of p < 0.05. Result. Push-out bond strengths were significantly influenced both by the post diameter and thermal cycling. Larger (1.5 mm) diameter post results were statistically higher than 1.2 mm results (p < 0.05). Moreover, TC significantly increased the bond strength results (p < 0.05). There was no significant difference between ZR and IPN posts (p = 0.219). Conclusion. The bond strengths of ZR and IPN posts were significantly decreased when the resin cement layer was thick. In addition, thermal cycling drastically influenced bond strengths of the tested post materials. Clinical significance: The fit between tooth-colored endodontic posts and post spaces should be as tight as possible.     

Effect of fluoridated milk on enamel and root dentin demineralization evaluated by a biofilm caries model

Although some studies suggest an anticaries effect of fluoridated bovine milk (F-milk) on enamel, evidence is still considered weak. Even more uncertain, the effect of F-milk on root caries remains largely unknown. This study evaluated the effect of F-milk on enamel and on root dentin demineralization using a validated Streptococcus mutans biofilm model, simulating a high cariogenic challenge. S. mutans (UA159) biofilms were formed on bovine enamel and root dentin saliva-coated slabs after measuring initial surface microhardness (SH). Biofilms were exposed to 10% sucrose 8×/day and treated 2×/day with either: (1) 0.9% NaCl (negative control), (2) bovine milk, (3) F-milk (5.0 ppm F as NaF) or (4) NaF 0.05% (anticaries-positive control). Medium pH was monitored twice/day, as a biofilm acidogenicity indicator. After 5 days for enamel and 4 days for dentin, biofilms were recovered to analyze: biomass, soluble proteins, viable microorganisms, and extra- and intracellular polysaccharides. Enamel and dentin demineralization were estimated by percentage of SH loss. Results were compared by ANOVA and Tukey's test. Neither acidogenicity nor biofilm composition differed among treatment groups in biofilms formed on enamel or dentin (p > 0.05). F-milk, however, significantly reduced enamel and dentin demineralization when compared with the negative control (p < 0.05). Also, F-milk was as efficient as 0.05% NaF to reduce enamel (p > 0.05), but not dentin demineralization (p < 0.05). These findings suggest that milk containing 5.0 ppm of fluoride is effective to control enamel caries and that it may be effective on root dentin caries prevention.     

Endoscopic findings in periapical surgery. A cross-sectional study of 206 roots

Background A study is made of the findings of high-magnification rigid endoscopy at the root end surface following apicoectomy of teeth subjected to periapical surgery.Material and Methods A cross-sectional study was made of patients subjected to periapical surgery at the Unit of Oral Surgery and Implantology (University of Valencia, Valencia, Spain) between 2011 and 2019. Following apicoectomy, the root end surfaces were inspected, with the evaluation of untreated canals, isthmuses, craze lines, crack lines, opaque dentin and gaps. Likewise, an analysis was made of the association between patient age and the tooth type and restoration and the presence of craze lines, cracks, opaque dentin and gaps.Results The final sample consisted of 168 patients subjected to periapical surgery, with 177 operated teeth and 206 roots. Untreated canals were observed in 14 roots (6.8%). Isthmuses were identified in 74 roots (35.9%), particularly in the mesial root of the lower first molar (94.1%). In turn, craze lines were identified in 8.3% of the roots, cracks in 3.9%, and gaps in 53.4%. The prevalence of opaque dentin was 78.3%, with a greater presence in posterior teeth (90.3% in premolars and 86.2% in molars) than in anterior teeth (50.6%) (p<0.001). Patient age and tooth restoration showed no correlation to the studied parameters.Conclusions Craze lines and crack lines were observed in less than 10% of the roots, though opaque dentin was identified in 73% of the roots, particularly in posterior teeth, and gaps were found in over half of the canals. Key words:Endoscope, cracks, gaps, opaque dentin, periapical surgery.     

Diffusion of medicaments within root canal dentin. A scanning electron microscopic study

Root canals of 21 maxillary human teeth were enlarged with reamers and flushed alternatively with sodium hypochlorite and hydrogen peroxide. After its mechanical preparation, root canals were dressed with camphorated paramonochloropherol and/or formocresol delivered by paper points. All three medicaments crystallize both on dentin walls and inside dentinal tubules. The clinical implications of these findings are discussed.     

Comparison of clinical outcome of periapical surgery in endodontic and oral surgery units of a teaching dental hospital: a retrospective study

OBJECTIVES: The aims of this retrospective study were (1) to compare the outcome of periapical surgery performed in endodontic and in oral surgery units of a teaching dental hospital and (2) to evaluate the influence of factors affecting outcome. STUDY DESIGN: A total of 176 teeth (endodontic unit, 83; oral surgery unit, 93) surgically treated more than 4 years previously were examined clinically and radiographically by means of strict criteria. Multiple logistic regression analysis was used. RESULTS: The rate of complete healing for patients treated in the endodontic unit (37.4%) was significantly (P = .009) higher than that for patients treated in the oral surgery unit (19.4%). The technical quality of surgery (P < .001), placement of root-end filling (P = .039), absence of a preoperative periapical lesion (P = .042), absence of a post (P = .047), and presence of an adequate coronal restoration (P = .056, odds ratio = 3.71) had significant effects on treatment outcome. CONCLUSION: The technical quality of periapical surgery, the presence of a periapical lesion, and adequate apical and coronal seal are important prognostic determinants of successful periapical surgery.     

Effects of Nd: YAG laser irradiation on the root canal wall dentin of human teeth: a SEM study

The purpose of this study was to observe the morphological and histological changes on the root canal walls after Nd:YAG laser application. Twenty vital, recently extracted single-rooted human teeth were used for this study. Root canals were cleaned and shaped by a conventional step-back technique--by means of k files up to a 20 k-file type at working length--and subsequently shaped by Ni-Ti root-canal rotary instrumentation up to 30/06 and irrigated with 2.5% hypochlorite solution. Ten teeth (control group) were left unlased, while the other ten teeth were irradiated with Nd:YAG laser by means of a 320 microns fibre inserted in the root canal at 1 mm from the apex with a power of 1.5 Watt and a frequency of 15 pps for five seconds in retraction with rotating movements. The control specimen showed debris and smear layer on the root canal surface obscuring the dentin tubules. The root canal walls irradiated with Nd:YAG laser showed a clear glazed surface, some open dentinal tubules and some surface craters with cracks. Such results confirm that smear layer and debris are removable with Nd:YAG laser, however clearing all root canal walls is still difficult and, if the energy level and duration of application are inadequate, a certain degree of thermal damage and morphological changes in dentin structure are observable.     

不同厚度体瓷的纳米陶瓷和普通陶瓷颜色的对比研究

目的研究体瓷厚度对纳米陶瓷和普通陶瓷颜色的影响。方法制作直径为10mm的纳米陶瓷和普通陶瓷体瓷试件各20个,每种陶瓷试件再分成4小组,厚度依次为0.5mm、1.0mm、1.5mm和2.0mm。使用SpectrascanPR-650型光谱扫描色度仪对试件颜色进行测量。结果①随着体瓷厚度的增加,纳米陶瓷组和普通陶瓷组的L＊值、a＊值、b＊值和C＊ab值均增加（P〈0.05）。②相同体瓷厚度时,纳米陶瓷组和普通陶瓷组的L＊值和a＊值均有差异（P〈0.01）。结论纳米陶瓷和普通陶瓷的体瓷厚度对其颜色均有影响,但对纳米陶瓷的影响小于普通陶瓷。如要增加陶瓷修复体的明度或降低其红色色调可选用纳米陶瓷。