Rotational relapse of anterior teeth following orthodontic treatment and circumferential supracrestal fiberotomy

Background/purposeSeveral factors cause relapse of orthodontically de-rotated teeth after appliance removal. Circumferential supracrestal fiberotomy (CSF) may release the tension on the supra-alveolar fibers following tooth de-rotation, thereby reducing the relapse risk. However, careful identification of the amount and location of relapse enables proper clinical evaluation. We aimed to determine the amount of orthodontic relapse following CSF for de-rotated anterior teeth.Materials and methodsEleven patients with 90 orthodontically de-rotated anterior teeth were enrolled. CSF was performed after orthodontic treatment, during fixed retainer placement. Rotational correction and relapse were measured on three casts (preorthodontic treatment, cast 1; postorthodontic treatment + CSF, cast 2; and 12-month follow-up, cast 3). The Wilcoxon test was used to assess significant differences in the tooth rotation angles between casts 1 and 2 and casts 2 and 3. The relationship between the magnitude of relapse and pretreatment severity of rotation was assessed by the point biserial correlation test. The Mann-Whitney U test helped in identifying significant differences in the amount of relapse between maxillary and mandibular teeth.ResultsThe mean amount of rotational correction was 14.05°, while the mean amount and percentage of relapse were 1.1° and 10.8%, respectively [0.81° (8%) and 1.44° (14%) for maxillary and mandibular teeth, respectively]. The relapse amount was proportional to the pretreatment rotation severity, and it was larger for the mandibular canines. There was no significant difference in the amount of relapse between the maxillary and mandibular teeth (P = 0.07).ConclusionPost-treatment rotational relapse of anterior teeth subjected to CSF was minimal and statistically insignificant after 1 year of follow-up. This validates the promising results of CSF when combined with appropriate mechanical retention for an adequate period.     

快速进展性牙周炎牙骨质表面形貌观察及微区成分分析

目的　观察快速进展性牙周炎患牙牙骨质的表面形貌并分析其微区成分 ,以明确快速进展性牙周炎患牙是否存在牙骨质异常。方法　用扫描电镜观察 1 0颗快速进展性牙周炎患牙、1 0颗慢性牙周炎患牙及 1 0颗牙周健康牙齿的牙骨质表面形貌 ,通过能谱分析测定牙骨质表面的微区成分 (Ca、P、Mg) ,着重对前两组患牙进行比较。结果　快速进展性牙周炎患牙牙骨质的表面形貌和慢性牙周炎患牙牙骨质的表面形貌基本相似 ,Ca(64 60 %± 2 2 9% ,63 54 %± 2 97% ,P >0 0 5)、P(32 54 %± 1 2 9% ,32 97%± 2 40 % ,P >0 0 5)、Mg(2 86 %± 1 2 9% ,3 48%± 1 0 2 % ,P >0 0 5)含量及Ca/P(2 0 0± 0 1 7,1 95± 0 2 5 ,P >0 0 5) ,差异均无显著性。结论　部分快速进展性牙周炎患牙可能不存在牙骨质异常     

Periostin对人牙周膜细胞在牙根片上附着和生长的影响

目的：研究小鼠重组Periostin对人牙周膜细胞（PDL细胞）在正常及病变牙根片上附着和增殖的影响。方法：将正常及病变根片分别用Periostin、FN和无血清DMEM处理后,观察PDL细胞在其上24h的附着量和72h增殖量,并在扫描电镜下观察其形态变化,结果：Periostin与阳性对照FN均可有效促进PDL细胞在政党及病变根面上的附着和增殖（P＜0．05－0．01）,二者促附着作用相近（P＞0．05）,但在促增殖方面,Periostin较FN作用明显弱（P＜0．05）。结论：小鼠重组Periostin对PLD细胞在正常及病变根片上的附着和增殖均有一定促进作用。     

高功率半导体激光对复杂根管消毒效果的体外研究

目的 评价高功率半导体激光联合次氯酸钠对体外复杂根管的消毒效果。方法 通过CBCT筛选含峡区的离体牙42颗,体外建立复杂根管感染模型,将离体牙随机分为4组,A组：半导体激光组+0.9% NaCl溶液; B组：半导体激光+5.25% NaClO; C组:5.25% NaClO; D组：空白对照组;每组10颗牙齿,经消毒处理后收集冲洗液,进行细菌培养、菌落形成单位计数、SEM观察及细菌活死染色后激光聚焦显微镜（ CLSM）观察分析,定量比较各组对粪肠球菌的杀灭效果。结果 ① A、B、C组处理后的杀菌率分别为33.9%、98.4%和82.8%,均高于D组的3.68%（ P<0.05）,其中B组杀菌率最高; ②扫描电镜结果显示：激光结合次氯酸钠组获得最好的根管壁清理效果; ③ CLSM图像荧光强度IOD值分析结果显示： B组红色荧光强度高于其余3组（ P<0.05）。结论 半导体激光辅助根管消毒有助于复杂根管（含峡区）的消毒;高功率（ 2.5 W）半导体激光结合传统根管化学消毒值得推广。     

Behavior of human periodontal ligament cells on CO2 laser irradiated dentinal root surfaces: an in vitro study

OBJECTIVE: The aim of this study was to investigate the in vitro attachment behavior of human periodontal ligament fibroblasts on periodontally involved root surface after conditioning with CO2 laser and to compare its efficacy with chemical conditioning agents, namely tetracycline hydrochloride, citric acid, hydrogen peroxide (H2O2) and EDTA, using scanning electron microscopy. METHODS: A total of 84 scaled and root-planed specimens from periodontally involved single-rooted human teeth showing hopeless prognosis were selected and assigned to two groups. One group was lased with a CO2 laser (from 5 cm at 3 W for 0.8, 1.0 and 1.2 s), and the other group was treated with either tetracycline hydrochloride (2.5%), citric acid (saturated solution, pH 1), H2O2 (6%) or EDTA (5%; pH 7.4) for 3 min. The specimens were then seeded with human periodontal ligament fibroblasts, incubated for either 12 h or 24 h, and then the cell attachment behavior was observed. RESULTS: CO2 laser irradiation for 1.0 s was found to be the most efficient, showing consistently good cell attachment with the highest mean value (15.00 +/- 3.41 cells/10,000 microm2 after incubation for 12 h and 29.17 +/- 2.04 cells/10,000 microm2 after 24 h), followed by irradiation for 0.8 s (13.11 +/- 3.04 cells/10,000 microm2 after incubation for 12 h and 22.91 +/- 7.10 cells/10,000 microm2 after 24 h). Charring was observed following irradiation for 1.2 s. Amongst chemical conditioning agents, citric acid was found to be the most efficient, with a mean cell attachment of 17.82 +/- 2.16 cells/10,000 microm2 after incubation for 12 h and 23.62 +/- 1.94 cells/10,000 microm2 after 24 h. EDTA and H2O2 did not do well in the study. CONCLUSION: The results suggest that CO2 laser irradiation for 1.0 s may promote comparatively better attachment of periodontal ligament fibroblast on dentinal root surfaces than the conventional chemical conditioning agents used in the study.     

Effectiveness of KTP laser versus 980 nm diode laser to kill Enterococcus faecalis in biofilms developed in experimentally infected root canals

This study aimed to evaluate the antibacterial action of KTP (potassium‐titanyl‐phosphate) laser irradiations (compared with 980 nm diode laser), associated with conventional endodontic procedures, on Enterococcus faecalis biofilms. Fifty‐six dental roots with single canals were prepared with Ni‐Ti rotary instruments, autoclaved, inoculated with an E. faecalis suspension and incubated for 72 h. They were randomly allocated to control and treatment groups. Laser parameters were as follows: power 2.5 W, Ton 35 ms, Toff 50 ms (KTP laser); power 2.5 W, Ton 30 ms, Toff 30 ms (980 nm diode laser). To evaluate the residual bacterial load, BioTimer Assay was employed. The chemo‐mechanical treatment together with laser irradiations (KTP and 980 nm diode lasers) achieved a considerable reduction of bacterial load (higher than 96% and 93%, respectively). Regarding both laser systems, comparisons with conventional endodontic procedures (mortality rate of about 67%) revealed statistically highly significant differences (P ≤ 0.01). This study confirms that laser systems can provide an additional aid in endodontic disinfection.     

Effect of radiant heat induced by a diode laser (445 nm) on setting process of glass-ionomer cements monitored by Fourier transform infrared spectroscopy

ObjectivesThe aim of this study was to investigate the effect of thermal energy induced by a diode laser (445 nm) on the setting reactions of conventional glass ionomer cements (GICs) by using Fourier transform infrared spectroscopy (FTIR) and to compare it with that induced by a LED device.MethodsFour GICs were investigated in this study (GlassIonomer FX Ultra, Ketac Universal Aplicap, Equia Fill, and Riva Self Cure). The experimental groups of the study were as follows (n = 5): Group 1 (control) – the specimens after mixing were left to set without any treatment; Group 2 – the specimens were irradiated for 60 s using a LED (Valo?) at 1400 mW/cm² (fluence ～ 1.4 J/cm²); Group 3 – the specimens were also irradiated for 60 s using a diode laser (SIROLaser Blue), which emits at 445 ± 5 nm with average output power of 0.7 W (fluence ～ 1.4 J/cm²). FTIR analysis of the GIC specimens was followed to assess the changes in the COO-/CO ratios of the setting reaction and its progress in time.ResultsBoth laser and LED treatments improved the setting reactions of the GICs compared to the control group (p < 0.05). However, this phenomenon was not observed in all materials implying that it may be material dependent.SignificanceRadiant heat treatments using diode laser or LED may be beneficial for the rate and progress of setting reaction of the conventional GICs. The composition and handling of the materials may be crucial for their final properties and the overall clinical behavior.     

The influence of hemostatic agents on dentin and enamel surfaces and dental bonding: A systematic review

Background.Hemostatic agents have been used clinically in dentistry for many years to control bleeding. The authors reviewed scientific publications in which researchers investigated the effects of hemostatic agents on dentin and enamel surfaces and on bonding of adhesive systems and resin cements.Types of Studies Reviewed.The authors screened PubMed and Scopus databases for studies in English published from 1980 to 2013. They read the titles and abstracts to identify literature that fulfilled the inclusion criteria. The authors included studies in which researchers evaluated the hemostatic action on the dentin and enamel surfaces or its influence on the bond strength of adhesive systems or resin cements. They used cross-referencing to identify more articles.Results.Twenty in vitro studies met the inclusion criteria. Investigators in 12 of these studies evaluated the bond strength to contaminated dentin. Investigators in 10 of these studies reported a significant decrease in bond strength. Those in two studies evaluated the influence of a hemostatic agent on the dental enamel and reported decreases in bond strength. Researchers also reported significant increases in microleakage of self-etching adhesives on contaminated dentin. Scanning electron microscopy revealed partial removal of the smear layer or an etching effect of dentin as a result of the application of hemostatic agents on dentin.Practical Implications.Adhesive procedures may be affected adversely when performed on dentin and enamel contaminated by hemostatic agents. Hemostatic agents may induce changes in the dentin surface morphology. The results of this review indicate that the bond strength of self-etching adhesive systems is affected more negatively than is that of etch-and-rinse systems. The authors found that a 60-second application of ethylenediaminetetraacetic acid followed by a water spray restored the bond strength of a self-etching adhesive to dentin; use of phosphoric acid for 15 seconds followed by a water spray also was an effective cleaning method. Direct comparison of selected studies was not possible, however, mainly because of methodological differences hampering definitive conclusions.