The effect of CO(2) laser irradiation on failed implant surfaces

The aim of this investigation was to evaluate the cleaning effect of CO(2) on surface topography and composition of failed dental implant surfaces. Ten failed dental implants were retrieved from nine patients (mean age, 46.33 +/- 5.81 years) as a result of early or late failure. The implants were divided into two parts: one side of the implant was irradiated with a CO(2) laser (test side), while the other side did not receive irradiation (control side). The CO(2) laser was operated at 1.2 W in a continuous wave for 40 seconds (40 J energy). The handpiece of the CO(2) laser was kept at a distance of 30 mm from the implant surface, resulting in a spot area of 0.031415 cm (38.20 W/cm; 1559 J/cm) in scanning mode (cervical-apical). One unused dental implant was used as a negative control for both groups. All implant surfaces were examined by scanning electron microscopy (SEM) and energy-dispersive spectrometer x-ray (EDS) for element analysis. SEM showed that the surface of the test sides consisted of different degrees of organic residues, appearing mainly as dark stains similar to those observed on the control sides. None of the test surfaces presented alterations such as crater-like alterations, lava-like layers, or melting compared with the nonirradiated surfaces. Foreign elements such as carbon, oxygen, sodium, calcium, and aluminum were detected on both sides. These results suggest that CO(2) laser irradiation does not modify the implant surface, although the cleaning effect was not satisfactory.     

Effect of low-power laser irradiation on bony implant sites

This study was designed to examine the effects of low-energy laser irradiation on osteocytes and bone resorption at bony implant sites. Five male baboons with a mean age of 6.5 years were used in the study. Four holes for accommodating implants were drilled in each iliac crest. Sites on the left side were irradiated with a 100 mW low-energy laser (690 nm) for 1 min (6 Joule) immediately after drilling and insertion of four sandblasted and etched (Frialit-2 Synchro) implants. Five days later, the bone was removed en bloc and was evaluated histomorphometrically. The mean osteocyte count per unit area was 109.8 cells in the irradiated group vs. 94.8 cells in the control group. As intra-individual cell counts varied substantially, osteocyte viability was used for evaluation. In the irradiated group, viable osteocytes were found in 41.7% of the lacuna vs. 34.4% in the non-irradiated group. This difference was statistically significant at P < 0.027. The total resorption area, eroded surface, was found to be 24.9% in the control group vs. 24.6% in the irradiated group. This difference was not statistically significant. This study showed that osteocyte viability was significantly higher in the samples that were subjected to laser irradiation immediately after implant site drilling and implant insertion, in comparison to control sites. This may have positive effects on the integration of implants. The bone resorption rate, in contrast, was not affected by laser irradiation.     

半导体激光照射对牙齿根尖封闭效果的研究

目的:探讨常规根管预备后使用半导体激光进行根管内照射对根尖封闭性能的影响.方法:选择新鲜拔除的单根管牙60 颗,分6 组(n=10),去除牙冠,常规根管预备.A、B组,半导体激光1 W照射20 s;C、D组,超声荡洗1 min;E、F组,不做任何处理,作为对照组.常规热牙胶垂直加压法充填6 组牙根.微渗漏实验对根充后的A、C、E组牙的根尖封闭性能进行评估,扫描电镜观察B、D、F组牙根剖面.结果:A、C、E组根管微渗漏(mm)分别为1.70±0.82、2.02±0.40和4.56±2.76(A vs E,P<0.01;C vs E,P<0.05,A vs C,P>0.05),扫描电镜观察到激光组大部分牙本质小管发生熔融、缩小或封闭,超声荡洗组大部分牙本质小管内有糊剂或牙胶进入.结论:半导体激光进行根管内照射可以显著提高根充后根尖的封闭性能.     

Influence of implant surfaces on osseointegration

The biological fixation between the dental implant surfaces and jaw bones should be considered a prerequisite for the long-term success of implant-supported prostheses. In this context, the implant surface modifications gained an important and decisive place in implant research over the last years. As the most investigated topic in, it aided the development of enhanced dental treatment modalities and the expansion of dental implant use. Nowadays, a large number of implant types with a great variety of surface properties and other features are commercially available and have to be treated with caution. Although surface modifications have been shown to enhance osseointegration at early implantation times, for example, the clinician should look for research evidence before selecting a dental implant for a specific use. This paper reviews the literature on dental implant surfaces by assessing in vitro and in vivo studies to show the current perspective of implant development. The review comprises quantitative and qualitative results on the analysis of bone-implant interface using micro and nano implant surface topographies. Furthermore, the perspective of incorporating biomimetic molecules (e.g.: peptides and bone morphogenetic proteins) to the implant surface and their effects on bone formation and remodeling around implants are discussed.     

Biofilm and cell adhesion strength on dental implant surfaces via the laser spallation technique

ObjectiveThe aims of this study are to quantify the adhesion strength differential between an oral bacterial biofilm and an osteoblast-like cell monolayer to a dental implant-simulant surface and develop a metric that quantifies the biocompatible effect of implant surfaces on bacterial and cell adhesion.MethodsHigh-amplitude short-duration stress waves generated by laser pulse absorption are used to spall bacteria and cells from titanium substrates. By carefully controlling laser fluence and calibration of laser fluence with applied stress, the adhesion difference between Streptococcus mutans biofilms and MG 63 osteoblast-like cell monolayers on smooth and rough titanium substrates is obtained. The ratio of cell adhesion strength to biofilm adhesion strength (i.e., Adhesion Index) is determined as a nondimensionalized parameter for biocompatibility assessment.ResultsAdhesion strength of 143 MPa, with a 95% C.I. (114, 176), is measured for MG 63 cells on smooth titanium and 292 MPa, with a 95% C.I. (267, 306), on roughened titanium. Adhesion strength for S. mutans on smooth titanium is 320 MPa, with a 95% C.I. (304, 333), and remained relatively constant at 332 MPa, with a 95% C.I. (324, 343), on roughened titanium. The calculated Adhesion Index for smooth titanium is 0.451, with a 95% C.I. (0.267, 0.622), which increased to 0.876, with a 95% C.I. (0.780, 0.932), on roughened titanium.SignificanceThe laser spallation technique provides a platform to examine the tradeoffs of adhesion modulators on both biofilm and cell adhesion. This tradeoff is characterized by the Adhesion Index, which is proposed to aid biocompatibility screening and could help improve implantation outcomes. The Adhesion Index is implemented to determine surface factors that promote favorable adhesion of cells greater than biofilms. Here, an Adhesion Index ? 1 suggests favorable biocompatibility.     

Nd: YAG激光对牙根面结构及变异链球菌黏附的影响

目的 研究不同功率的水冷Nd: YAG激光照射治疗对牙根面结构及变异链球菌黏附的影响。方法 将因重度慢性牙周炎拔除的离体牙分为4组,均进行手工刮治和根面平整,制备牙根片,激光1、2、3组分别用功率为4、6、8 W的水冷Nd: YAG激光照射处理60 s,对照组不作处理。用扫描电子显微镜（SEM）观察各组根片的表面结构。将变异链球菌接种于各组牙根片表面并进行培养,计数各组根片表面细菌的黏附量（CFU·mL-1）;同时用SEM观察对照组及激光2组根面的细菌黏附情况。结果 SEM观察根片表面结构,激光组较对照组牙根表面的玷污层、碎屑及菌斑样物质附着减少,但裂隙增多。3个激光组牙根表面的细菌黏附量均少于对照组（P<0.05）,而不同功率的激光组之间的差异无统计学意义（P>0.05）。SEM观察细菌黏附情况,激光2组表面的细菌黏附量明显少于对照组。结论 与单纯刮治相比,刮治后进行水冷Nd: YAG激光治疗能清除牙根表面的玷污层、碎屑及菌斑样物质,并能减少变异链球菌的黏附,但激光会导致牙根表面出现裂隙。本实验中,6 W为激光最佳功率,既能较好地去除牙根表面的玷污层和碎屑等,又能较好地控制激光对根面的热损害程度。     

The effect of CO2 laser irradiation on PDL cell attachment to resected root surfaces

OBJECTIVES: The effect of CO2 laser irradiation on PDL attachment to resected root ends was evaluated. STUDY DESIGN: Forty dentin wafers were divided into 4 equal groups. Groups I and II were not subjected to laser irradiation. Groups III and IV were subjected to irradiation with CO2 laser (wave length 10.6 mm). PDL cells attachment to the resected root surface (lased/non lased) and cell attachment to the root end filling material (gutta percha and MTA) were evaluated utilizing immunoflouresence microscopy and SEM. RESULTS: PDL cell attachment was observed on dentin surfaces (control samples) and dentin away from the laser strikes (irradiated samples). PDL cell attachment was observed on MTA but was absent on gutta percha. CONCLUSION: Absence of PDL attachment to laser irradiated dentin could be attributed to morphological surface changes in dentin produced by laser irradiation.     

Bactericidal effect of the Er:YAG laser on dental implant surfaces: an in vitro study

BACKGROUND: The aim of the in vitro study was to examine the bactericidal effect of an Er:YAG laser on common dental implant surfaces. METHODS: Seventy-two titanium platelets with 3 different surfaces--sandblasted and acid-etched (SA), titanium plasma-sprayed (TPS), and hydroxyapatite-coated (HA)--were incubated with a suspension of Streptococcus sanguinis (ATCC 10556). Irradiation at pulse energies of 60 and 120 mJ and a frequency of 10 pps was performed on a computer-controlled XY translation stage. After laser treatment the specimens were sonicated and the bacterial growth examined by counting colony forming units on blood agar plates. Temperature elevations during irradiation were investigated using K-type thermocouples. Laser treated implant surfaces were analyzed by means of electron microscopy. RESULTS: Compared to non-irradiated specimens, mean bacterial reductions of 99.51% (SA), 98.39% (HA), and 99.6% (TPS) at a pulse energy of 60 mJ and 99.92% (SA), 99.85% (HA), and 99.94% (TPS) at 120 mJ were calculated. At these laser parameters, no excessive temperature elevations or morphological implant surface alterations were detected. CONCLUSIONS: Even at low energy densities, the Er:YAG laser has a high bactericidal potential on common implant surfaces. Clinical studies are justified to evaluate the applicability and efficacy of the Er:YAG laser in the treatment of peri-implantitis.     

Primary bacterial colonization of implant surfaces

The purpose of this study was to assess the effects of modifying titanium surfaces, in terms of wettability, roughness, and mode of sterilization, on the ability of the oral bacterium Streptococcus sanguis to colonize. An in vitro model system was developed. All surfaces were colonized by the bacteria, but to significantly different levels. Titanium samples that exhibited rough or hydrophobic (low wettability) surfaces, along with all autoclaved surfaces, were preferentially colonized (P < .01). Titanium surfaces that had been repeatedly autoclaved were colonized with the levels of bacteria 3 to 4 orders of magnitude higher than other modes of sterilization. This may have implications relative to the commonly used method of autoclaving titanium implants, which may ultimately enhance bacterial biofilm formation on these surfaces.     

半导体激光根管内照射与牙根表面温度变化的关系

目的采用不同功率半导体激光根管内连续照射或间隔照射,观察3种照射模式对根管外壁温度升高的影响。方法实验一:60颗离体单根管牙分A组(功率1.5 W)与B组(功率3 W),每组又分为3亚组(A1、A2、A3),每组10颗,采用三种不同照射模式:A1:照射5s 4次,A2:照射10 s 2次,单次照射间均间隔5 s;A3:连续照射20 s,同时测定根管外壁平均温度的变化。实验二:30颗离体单根管牙,采用功率1.5 W,连续照射20 s的模式,测定牙根外三点:G1(根尖点)、G2(根尖1/3)、G3(根中1/3)温度变化值。结果 A组中,A1、A2、A3照射模式下根管外壁温度升高均值分别为4.78℃,5.21℃,5.97℃,3组间无明显统计学差异。B组于相同照射模式下温升均值均大于A组,且B3模式下根管外壁温度升高最高可达10.3℃。相同照射条件下,根尖(G1点)温度升高明显低于根尖1/3(G2点)及根中1/3(G3点)的温度(P<0.05),G2、G3间无显著统计学差异。结论照射模式及激光功率对根管外壁温度改变均有显著影响,且不同部位升温幅度也不相同。功率1.5 W条件下,本实验设计的3种不同照射模式,均是临床较为安全的使用参数。     

Antimicrobial effects of 2.94 microm Er:YAG laser radiation on root surfaces: an in vitro study

OBJECTIVES: This in vitro study investigated the antimicrobial effects of 2.94 microm Er:YAG laser radiation on root surfaces. MATERIALS AND METHODS: The study used 125 extracted teeth which were divided into 2 groups (A, B) of 40 teeth and 3 groups of 15 teeth (C, D, E). A defined and similarly-sized area of the root surface was inoculated with an aliquot of 7 microl of a bacterial suspension of Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Actinobacillus actinomycetemcomitans (ATCC 43719), Eikenella corrodens (ATCC 51724), or Peptostreptococcus micros (ATCC 33270). Subsequently, the samples from each group were further divided into subgroups which have been irradiated either with 55, 75, and 105 (group A, B) or 55 and 75 (group C, D, E) laser pulses. 1 subgroup of each group was left untreated as control. The source of laser radiation was an Er:YAG laser emitting pulsed infrared radiation at a wavelength of 2.94 microm. The number of bacteria was determined using the surface spread plate technique. The statistical analysis was performed using ANOVA followed by the Scheffé-test. RESULTS: Depending on the number of laser pulses the bacterial load in the E. coli group was reduced by the Er:YAG laser radiation after exposure to 105 laser pulses to 5.5% of the initial count and that in the Staph. aureus group to 15.1%. The number of bacteria in case of A. actinomytemcomitans was reduced to 8.3%, in case of E. corrodens to 3.0% and in case of P. micros to 22.0% after application of 75 laser pulses. CONCLUSION: Besides the selective removal of plaque and calculus, the 2.94 microm Er:YAG laser radiation causes reduction in bacteria on root surfaces.     

Elimination of bacteria on different implant surfaces through photosensitization and soft laser. An in vitro study.

Microbiologic examinations of implants have shown that certain micro‐organisms described as periodontal pathogens may have an influence on the development and the progression of peri‐implant disease. This experimental study aimed to examine the bactericidal effect of irradiation with a soft laser on bacteria associated with peri‐implantitis following exposure to a photo‐sensitizing substance. Platelets made of commercially pure titanium, either with a machined surface or with a hydroxyapatite or plasma‐flame‐sprayed surface or with a corundum‐blasted and etched surface, were incubated with a pure suspension of Actinobacillus actinomyetemcomitans or Porphyromonas gingivalis or Prevotella intermedia. The surfaces were then treated with a toluidine blue solution and irradiated with a diode soft laser with a wave length of 905 nm for 1 min. None of the smears obtained from the thus treated surfaces showed bacterial growth, whereas the smears obtained from surfaces that had been subjected to only one type of treatment showed unchanged growth of every target organism tested ( P <0.0006). Electron microscopic inspection of the thus treated platelets revealed that combined dye/laser treatment resulted in the destruction of bacterial cells. The present in vitro results indicate that lethal photosensitization may be of use for treatment of peri‐implantitis.     

Effect of plastic-covered ultrasonic scalers on titanium implant surfaces

Objectives: Maintaining oral health around titanium implants is essential. The formation of a biofilm on the titanium surface will influence the continuing success of the implant. These concerns have led to modified ultrasonic scaler instruments that look to reduce implant damage while maximising the cleaning effect. This study aimed to assess the effect of instrumentation, with traditional and modified ultrasonic scalers, on titanium implant surfaces and to correlate this with the oscillations of the instruments. Materials and methods: Two ultrasonic insert designs (metallic TFI‐10 and a plastic‐tipped implant insert) were selected. Each scaler probe was scanned using a scanning laser vibrometer, under loaded and unloaded conditions, to determine their oscillation characteristics. Loads were applied against a titanium implant (100g and 200 g) for 10 s. The resulting implant surfaces were then scanned using laser profilometry and scanning electron microscopy (SEM). Results: Insert probes oscillated with an elliptical motion with the maximum amplitude at the probe tip. Laser profilometry detected defects in the titanium surface only for the metallic scaler insert. Defect widths at 200 g high power were significantly larger than all other load/power conditions (P<0.02). Using SEM, it was observed that modifications to the implant surface had occurred following instrumentation with the plastic‐tipped insert. Debris was also visible around the defects. Conclusions: Metal scalers produce defects in titanium implant surfaces and load and power are important factors in the damage caused. Plastic‐coated scaler probes cause minimal damage to implant surfaces and have a polishing action but can leave plastic deposits behind on the implant surface. To cite this article:
Mann M, Parmar D, Walmsley AD and Lea SC. Effect of plastic covered ultrasonic scalers on titanium implant surfaces.
Clin. Oral Impl. Res. 23 , 2012; 76–82
doi: 10.1111/j.1600‐0501.2011.02186.x     

半导体激光在下颌第三磨牙拔除术后并发症预防的应用进展

下颌阻生第三磨牙拔除术是牙槽外科一项较为复杂的手术。其术后的主要并发症为拔牙后疼痛、面部肿胀反应、感染、干槽症、拔牙术后出血、颞下颌关节紊乱综合征和开口受限等。半导体激光器发展至今,在诸多领域中都得到了广泛应用。本文通过对激光生物学效应的探讨,对半导体激光在下颌第三磨牙拔除术后并发症预防方面的作用作一综述。     

Antimicrobial treatment of peri‐implant infections

The purpose of this study was to investigate the possibility of antimicrobial treatment of peri-implant infections associated with a periodontitis-like subgingival microbiota. Nine partially or fully edentulous patients with titanium hollow cylinder implants were selected which showed loss of bone and probing depths > or = 5 mm on one or several implants after at least 6 months following installation. They also yielded subgingival microbial samples with > or = 10(6) CFU/ml, including > or = 20% gram-negative anaerobic bacteria. The treatment included mechanical cleaning, irrigation of all peri-implant pockets > 3 mm with 0.5% chlorhexidine and systemic antimicrobial therapy (1000 mg ornidazole for 10 consecutive days). After therapy, bleeding scores decreased immediately and, over a one-year observation period, remained significantly lower than before treatment. A significant gradual reduction in mean probing depths was detected over this one-year period; only one case showed no improvement of local probing depth. Microbiological parameters indicated an instantaneous quantitative and qualitative change following treatment. Subsequently, several of these parameters tended to shift back towards pretreatment values. In the second half of the observation period, however, this tendency was reversed, and levels significantly different from baseline were eventually established. This study demonstrated that treatment aiming at reducing the subgingival bacterial mass and suppressing the anaerobic segment had a beneficial effect in patients suffering from peri-implantitis.     

转移因子联合半导体激光治疗复发性阿弗他溃疡的短期疗效观察

目的探讨转移因子（TF）口服治疗联合半导体激光治疗复发性阿弗他溃疡（RaU）的疗效及不良反应。方法将门诊100例RAU患者随机分为两组,治疗组60例,采用转移因子口服治疗联合半导体激光治疗：对照组40例,口服维生素C片剂和维生素B2,地塞米松粉剂涂搽溃疡处。两组分别观察1、2个疗程治疗结束后2周的临床疗效及不良反应。结果1个疗程治疗后2周治疗组的有效率（81．67％）高于对照组（55．0％）（P〈0．05）;2个疗程后2周治疗组有效率（86．67％）显著高于对照组（47．5％）（P〈0．05）。两组比较差异均有统计学意义（均为P〈0．05）。两组均未出现不良反应。结论应用转移因子口服治疗联合半导体激光治疗RAU有良好的短期治疗效果,无明显不良反应,能够明显的提高治疗RAU的有效率。