KTP and Er:YAG laser dental bleaching comparison: a spectrophotometric, thermal and morphologic analysis.

The aim of this study was to compare the results, in terms of temperature, colour change and morphology, of two different laser wavelengths with two different concentrations of hydrogen peroxide (HP). The lasers used were KTP (potassium-titanyl-phosphate) laser (λ = 532 nm (PD = 1.98 W/cm2)) and Er:YAG laser (λ = 2940 nm (PD = 2.54 W/cm2)). The bleaching gels used were PolaOffice 35% HP gel and PolaOffice+ 6% HP gel (SDI, Australia). Thirty-six extracted human teeth were selected and divided into two groups. For the 35% HP treatment, 18 teeth were randomly assigned to three subgroups: (1) HP gel without laser irradiation vs. HP gel + KTP laser irradiation; (2) HP gel without laser irradiation vs. HP gel + Er:YAG irradiation; and (3) HP gel + KTP laser irradiation vs. HP gel + Er:YAG irradiation. The same protocol was used for the 6% HP bleaching treatment. The bleaching results were analysed by a spectrophotometer, the thermal elevation by K thermocouples and the enamel surface by a scanning electron microscope (SEM). The Kruskal-Wallis test and the Mann-Whitney test were performed, and the data were analysed using the software StatView and the free Web statistics tool BiostaTGV. The thermal elevation of the Er:YAG groups was higher than KTP, while only the group 35% HP gel vs. 35% HP gel + Er:YAG showed significant colour differences (p < 0.05). SEM photographs showed slight enamel surface morphologic alterations after bleaching treatment. The Er:YAG laser may improve the bleaching results of 35% HP even if it increases the gel temperature, when compared to the KTP laser.

Comparison of two different laser wavelengths' dental bleaching results by photo-Fenton reaction: in vitro study.

The purpose of this study was to perform a preliminary in vitro test on the possible use of two different laser wavelengths, 405 and 532 nm, to improve the dental bleaching results. To perform the test, the degradation of a dye, rhodamine B, under the effects of hydrogen peroxide was used. One hundred and twenty vials were divided into four groups of 30 samples each and, while three of them were irradiated with different wavelengths, 365 nm (reference), 405 nm and 532 nm, the fourth was the non-irradiated control group. Each of the four groups was further divided into three subgroups of 10 cuvettes (n = 10) each. The three subgroups included a group with a rhodamine (RH) solution, a rhodamine and hydrogen peroxide (RH + HP) solution and a rhodamine plus hydrogen peroxide and ferrous gluconate (RH + FR) solution. When hydrogen peroxide was present, only UVA irradiation was able to produce significant results, whereas when the photo-Fenton reaction occurred, all the three wavelengths were able to produce a significant degradation of rhodamine B, with better results for longer wavelengths in comparison with short wavelengths. Within the limitations of this in vitro study, the light of the two laser devices, even remaining less effective than UV activation, showed its ability to improve the performance of bleaching agents based on Fenton photocatalysis, whereas when used in combination with hydrogen peroxide only, the 405-nm laser displayed a small effect and the 532-nm laser produced no effects.

Er:YAG laser for brackets bonding: a SEM study after debonding.

BACKGROUND: The introduction of Er:YAG laser in dentistry for ablation of hard tissues advocated an alternative method of enamel etching for orthodontics purpose. MATERIALS AND METHODS: 55 extracted human third molars were inserted in acrylic resin blocks and divided into five groups of 11 teeth. Group 1 was treated with 37% orthophosphoric acid for 30 seconds. Group 2 was treated with laser irradiation (Er:YAG Fidelius III, Fotona, Slovenia) at 80 mJ and 4 Hz. Group 3 underwent laser treatment (80 mJ, 4 Hz), followed by 37% orthophosphoric acid for 30 seconds. The teeth in Group 4 were treated with laser at 40 mJ and 10 Hz. The teeth in Group 5 were treated with laser (40 mJ, 10 Hz), followed by 37% orthophosphoric acid for 30 seconds. The adhesive remnant index was determined after debonding. RESULTS: Kruskas-Wallis test showed that location parameters (median and mean) are significantly different between Groups 2 and 4 when compared with control group; on the contrary no significant difference was detected between Groups 3 and 5 with the controls. CONCLUSION: The use of Er:YAG laser alone, as in Groups 2 and 4, showed no significant advantages over phosphoric acid in the bonding procedure for orthodontics brackets.

Low energy KTP laser in oral soft tissue surgery: A 52 patients clinical study.

OBJECTIVES: Since 1962 laser appliances have been used for soft tissues surgery of oral cavity with significant advantages compared to the traditional instruments: excellent bleeding control, possibility to avoid the use of suture, good patient compliance thanks to a decrease of intra- and post-operative discomfort and biostimulating effect. Unfortunately, the wavelengths so far used have been seen to cause, in association with an excellent ablation capacity, heat damage of the tissues that can decrease healing process and cause a greater discomfort to patients. To evaluate the laser-assisted KTP laser surgery at low power in terms of characteristics of intervention and patients compliance. STUDY DESIGN: In this study, we describe the application of a new and recently introduced in dentistry wavelength, the KTP laser (532 nm), used with low power parameter (1 Watt - CW), evaluating the time of interventions and, by a Numerical Rating Scale, the intra and postoperative pain. RESULTS: KTP laser used at low power permits to obtain good pain control during operations that were carried out with only a topic anaesthetic (EMLA, Astratech), as shown in VAS tests. Good healing with limited or absent burning areas in treated portion of tissue. CONCLUSIONS: These preliminary study allows us to affirm that KTP laser with low parameters permits to perform oral surgery with good pain control and good wound healing. A greater number of clinical cases are however necessary to confirm the result obtained.

Intra-oral laser welding: an in vitro evaluation of thermal increase.

The neodymium:yttrium-aluminium-garnet (Nd:YAG) laser is currently used in dental laboratories to weld metals on dental prostheses. Recently, the use of Nd:YAG has been suggested so that dentists themselves can repair broken fixed, removable and orthodontic prostheses by welding metals directly in the mouth. This work aimed to evaluate, through a four k-type thermocouple system on calf jaws, the thermal increase in the biological structures close to the metal parts during laser welding. We put two hemispherical metal plates onto mandibular molars and then laser welded them at three points with a four k-thermocouple system to determine the thermal rise in the pulp chamber, sulcus, root and bone. This procedure was carried out on 12 samples, and the results were processed. The highest values of thermal increase were found in the pulp chamber, 1.5 degrees C; sulcus, 0.7 degrees C; root, 0.3 degrees C; and bone, 0.3 degrees C. This study showed that thermal increases in pulp chamber, sulcus, root and bone were biologically compatible and that intra-oral laser welding, at the parameters used in this work, seems to be harmless to the biological structures close to the welding and thermally affected zones.

Enamel and dentine of deciduous teeth Er:YAG laser prepared. A SEM study.

AIM: The aim of this study was to observe dentine and enamel surfaces of deciduous teeth under SEM after cavity preparation with Er:YAG laser using different fluences. The results showed that when using Er:YAG laser for cavity preparation in deciduous teeth, no carbonisation or cracks were observed on the enamel and dentine surfaces using energy output between 150-250 Mj, and frequency 15 Hz. The SEM images of the dentine and enamel surfaces were similar to previous studies on permanent teeth: enamel with a typical "lava flow" appearance as a result of an open core of the prism that has lost its typical hexagonal aspect and the dentine with opened tubules plus a difference in the mineral thickness between peritubular and intertubular. CONCLUSION: The difference between the SEM images of deciduous enamel and dentine when using three different energies (150-200-250 mJ) is not significant in order to recommend the use of one type of output energy. In addition, the SEM images are similar TO those of permanent teeth.

Open abdomen management with human acellular dermal matrix in liver transplant recipients.

BACKGROUND: Abdominal wall closure after liver transplantation is not always feasible and may result in increased intra-abdominal pressure along with associated complications. Various temporary closure techniques as well as open wound management have been used to address this complex problem. The aim of this series was to describe an approach to definitive wound closure of the open abdomen in liver transplant patients. METHODS: We performed a retrospective review of all liver transplant patients at our institution from September 2005 to November 2007. The management of the open abdomen in 10 liver transplant patients was reviewed, and a novel approach described to manage these defects. RESULTS: Ten patients with open wounds were closed during the study period using human acellular dermal matrix (HADM). There were 7 men and 3 women of median age 55 years. Average size of HADM was 235 cm(2). The median follow-up is 10 months with no incidence of evisceration or hernia. In 1 patient, the graft failed along the lateral side due to infection; it dislodged during vacuum-assisted closure dressing change in another patient at 5 months after closure. Fascial closure was not possible due to organ edema (n = 3), a large liver (n = 4) or wound infection with dehiscence (n = 3). CONCLUSIONS: HADM can be used for primary wound closure in both clean and contaminated wounds as an alternative to an open abdomen post-liver transplantation.

The use of Erbium:YAG laser for caries removal in paediatric patients following Minimally Invasive Dentistry concepts.

AIM: The Er:YAG laser has proven to be effective and efficient in dental hard tissue ablation. The Minimally Invasive Dentistry (MID) approach in caries removal is to stop the disease process and to restore lost tooth structure and function, maximizing the health potential of the tooth. One of the most important concepts of the MID is to preserve as much as possible the dental tissue and this approach is even more important in primary dentition where the dimensions of the crown are smaller and the dimension of the pulp chamber is bigger in relationship to the crown. After treating 30 children's teeth (primary molars and first permanent molars) with the Er:YAG laser, we come to conclusion that laser treatment possesses the requirements of Minimal Invasive Dentistry: the possibility to ablate small area of infected layer guarantees maximum conservation of the tooth structure; using the antibacterial property of the Er:YAG laser we can decontaminate the affected layer that retains its remineralising potential; the lack of smear layer after vaporization with laser assures a better retention of the composite resin to the dentine; preparing the enamel surface with laser before etching gives a better marginal seal of the composite restoration.

Nd:YAG and diode laser in the surgical management of soft tissues related to orthodontic treatment.

OBJECTIVE: The aim of this clinical study was to observe and evaluate the surgical management efficiency of soft tissues during orthodontic treatment. MATERIALS AND METHODS: Thirty-seven young patients were selected and treated by laser-assisted surgery before or during orthodontic treatment and were classified by sex, age, and type of surgical management. Three different wavelengths were used (diode 810 nm, diode 980 nm, and Nd:YAG 1064 nm) in different surgical situations: maxillary vestibular and lingual frenectomies, surgical exposure and alignment of ectopic or retained teeth, and re-contouring gingival overgrowth. RESULTS: In all evaluated patients, the laser treatment was performed without local anesthesia or sutures. Only topical anesthetic was needed. CONCLUSION: These use of these wavelengths of laser energy was a noticeable aid in the surgical management of soft tissues before or during orthodontic treatment. The benefits of laser treatment include reduced bleeding during surgery with consequent reduced operating time and rapid postoperative hemostasis, thus eliminating the need for sutures. The lack of need for anesthetics and sutures, as well as improved postoperative comfort and healing, make this technique particularly useful for very young patients.

Pancreas Transplantation Is Feasible in Donors With Shprintzen-Goldberg Syndrome.

Shprintzen-Goldberg syndrome (SGS) is an autosomal dominant connective tissue disorder. To date, this report is the first account of a successful pancreas transplantation from an SGS donor. The similarity of the outcomes from previous year-on-year pancreas transplantations at the same center demonstrates promising results. Increasing awareness of the utilization of donors with SGS may promote expansion of center-specific criteria for organ acceptance. Therefore, every consideration should be given for use of organs from donors with this genetic abnormality because there is no evidence to suggest poorer allograft viability.

The Pancreas Can Take the Cold: Lower Waitlist Times Through Importation.

BACKGROUND: Our center has used a strategy of pancreas importation owing to long regional waitlist times. Here we assess the clinical outcomes and financial considerations of this strategy. METHODS: This was a retrospective observational cohort study of patients who received a pancreas transplant at Montefiore Medical Center (MMC) from 2014 to 2017 (n = 28). Clinical parameters, including hemoglobin A1c and complications, were analyzed. The cohort was compared with United Network for Organ Sharing (UNOS) Region 9 with the use of the UNOS/Organ Procurement and Transplantation Network database. Cost analysis of length of stay (LOS), standard acquisition (SAC) fees, and transportation was performed with the use of internal financial data. RESULTS: Pancreas importation resulted in significantly shorter simultaneous pancreas kidney transplant waitlist times compared with Region 9: 518 days vs 1001 days (P = .038). In addition, postoperative complications and 1-year HbA1c did not differ between groups: local 6.30% vs import 6.17% (P = .87). Patients receiving local pancreata stayed an average of 9.2 days compared with 11 days for the import group (P = .36). As such, pancreas importation was associated with higher mean charges ($445,968) compared with local pancreas recipients ($325,470). CONCLUSIONS: Long waitlist times in Region 9 have encouraged our center's adoption of pancreas importation to address the needs of our patient population. This practice has resulted in a reduction of waitlist times by an average of 483 days. Understandably, centers have long been wary of importation owing to perceived risk in clinical outcomes. In our single-center experience, we have demonstrated equivalent postoperative glucose control and graft survival. Importantly, there does appear to be increased costs associated with importation, which are mainly driven by LOS. Curiously, importation from regions with lower SAC fees has the potential to offset costs related to transportation expenses. Notwithstanding these findings, pancreas importation does have the potential to lessen the financial societal burden through reduction in waitlist times.

Pulpal and periodontal temperature rise during KTP laser use as a root planing complement in vitro.

OBJECTIVE: The purpose of this study was to define the optimal irradiation conditions of a KTP laser during root planing treatment. METHODS: The surfaces of 60 single-root human teeth were scaled with conventional instruments before lasing. The pulpal temperature increase was measured by means of one thermocouple placed in the pulp chamber and a second one placed on the root surface at 1 mm from the irradiation site. The influence of variables of coloration by Acid Red 52 (photosensitizer), scanning speed, dentin thickness, and probe position was analyzed for a constant exposure time of 15 sec and 500 mw (spot size diameter, 0.5 mm). The pulpal temperature was below 3 degrees C for the adjustments. RESULTS: The irradiation on one point of root surface had the following results: The application of photosensitizer on the root surface before lasing produced a 50% higher temperature rise within the pulp than in the case without the application of the photosensitizer. The temperature rise in the pulp chamber was below 3 degrees C with the following settings of 500 mw: PW = 10 msec and PRR < 35; or PW= 20 msec and PRR < 20 Hz. On the other hand, for the same irradiation conditions, the temperature rise on the surface of the root was always below 7 degrees C. However, the temperature increase became higher than 7 degrees C (on the surface of the root) in the case of P > 500 mw, PW > 50 msec and PRR > 10 Hz of root surface or a scanning speed of irradiation of 1 mm/sec for a linear irradiation of 4 mm. CONCLUSION: The KTP laser may be used safely without thermal damage to pulp and periodontal tissue with respect to the biologically acceptable previously described parameters.

405 nm diode laser, halogen lamp and LED device comparison in dental composites cure: an "in vitro" experimental trial.

BACKGROUND AND AIMS: A 405 nm diode laser is indicated for composite materials polymerizing, thanks to the recent evolution in their compositions, absorbing in blue part of the spectrum. The purpose of this research was to evaluate its performance on two different kinds of composite resins. MATERIALS AND METHODS: Two different composites were polymerized with a traditional halogen lamp, a LED device and a 405 nm diode laser. The depth of the cure, the volumetric shrinkage, and the degree of the conversion (DC%) of the double bond during the curing process were measured. One-way ANOVA test, Kruskal-Wallis tests, and Dunn comparison tests were used for statistic analysis. RESULTS: Regarding the depth of polymerization, the laser had the worst performance on one composite while on the other, no significant difference with the other devices was observed. The volumetric shrinkage showed that laser produced the lowest change in both of the composites. The DC% measure confirmed these findings. CONCLUSIONS: Based on the results of this preliminary study, it is not possible to recommend the 405 nm diode laser for the polymerization of dental composites.

Removal of Thermafil root canal filling material.

The aim of this study was to evaluate if removal of Thermafil plastic carriers and reestablishment of working length were possible in single rooted teeth filled with the Thermafil system. Twenty freshly extracted maxillary central incisors were prepared and filled with #30 Thermafil plastic obturators according to manufacturer's recommendations. Teeth were divided in two groups: Group I: 10 teeth were retreated using dimethylformamide as a solvent. Group II: 10 teeth were retreated using chloroform as a solvent. Removal of filling material was performed manually using K files and H files alternately between carrier and dentinal walls. The average time needed to remove the plastic carrier was 7 min for group I and approximately 6 1/2 min for group II. No deformation of the plastic carrier was observed after removal from the canal. Removal of plastic carriers and measurement of the proper working length were easily performed using manual endodontic instruments. Chloroform greatly enhanced this procedure.

Antimicrobial activity of amalgams, alloys and their elements and phases.

OBJECTIVES: This in vitro study aimed to evaluate the antibacterial effect of amalgams, alloys, elements and phases against two cariogenic bacteria, Actinomyces viscosus and Streptococcus mutans. METHODS: Test materials comprised: (i) commercial amalgams comprising Amalcap (Vivadent), Cavex Avalloy LC and DP (Cavex), Cupromuc (Merz), Fluoralloy and Synalloy (Dentoria); (ii) Ag-Cu alloy; (iii) gamma, gamma 1, gamma 2 and Cu6Sn5 phases; (iv) pure metal samples and chloride solutions of copper, mercury, tin and zinc; and (v) aqueous sodium fluoride. Bacterial suspensions of each of the two bacteria were grown in the presence of the test materials for 24 h. Antimicrobial effectiveness was assessed by measuring reduction in optical density at 640 nm using a visible spectrophotometer. RESULTS: Cupromuc/Fluoralloy, non gamma 2 amalgams and Amalcap displayed high, moderate and no antibacterial activity, respectively. Antibacterial effectiveness was not related to copper content. Whereas mercury, copper, Ag-Cu alloy, fluoride and zinc showed antibacterial activity (Hg > Cu > F > Zn), tin, gamma phases and Cu6Sn5 showed no such activity. SIGNIFICANCE: Although the fluoride and copper solutions were most effective at 50 micrograms ml-1 concentration, their antibacterial action was still significant, albeit reduced, at 10 micrograms ml-1 concentration. This was not the case for mercury chloride which was just as effective at both concentrations. Our results show that although mercury and copper contribute significantly to the antibacterial properties of amalgams, a high copper content does not necessarily relate to high antibacterial effectiveness. These elements could be useful in conferring antibacterial properties to amalgam although their effects on host cells must be investigated.

Antibacterial properties of five dental amalgams: an in vitro study.

The antibacterial activity of five commercially available amalgams (Cupromuc, Dispersalloy, Fluoralloy, Predalloy, and Synalloy) against two bacterial species frequently isolated from dental plaque and caries (Actinomyces viscosus and Streptococcus mutans) was studied by use of a modification of the method of Orstavik (1985). All amalgams displayed some antibacterial properties. This antibacterial activity was amalgam- and bacteria-dependent. Cupromuc and Fluoralloy were the most active, and the non-gamma 2 amalgams showed intermediate activity. Combined with mechanical and biological properties, these differences should be taken into account when one is choosing an amalgam for clinical use.

Experimental single controlled study of burned bones: contribution of scanning electron microscopy.

Burned bones were studied using Scanning Electron Microscopy. The samples were cut from a maxillary-mandibular block taken during an autopsy. These fragments were heated in a furnace under controlled temperature conditions for 60 minutes. The temperatures ranged from 150 to 1150 degrees Celsius. The results are as following: (i) there are significant alterations of the bone, more and more obvious as the temperature increases, (ii) it appears to be difficult to establish a precise correlation between the temperature and the scanning electron microscopy patterns.

Macroscopic and microscopic aspects of incinerated teeth.

Fifty-eight premolars, extracted for orthodontic reasons, were incinerated for one hour in a furnace at temperatures varying from 150 degrees C to 1150 degrees C, increasing at 100 degrees C intervals. Between 150 degrees C and 700 degrees C the teeth changed from light yellow to bluish-white passing through brown. The scanning electron microscope showed that at 150 degrees C cracks appeared in the enamel, increasing in number as the temperature rose. At 450 degrees C the internal surface detached from the dentine and showed the same cracked surface as the exterior. Above 1100 degrees C the enamel fragments had a prismatic structure difficult to identify due to their melted structure. Dentine retained its tubular structure up to 1150 degrees C even when the tubules' diameter decreased at 700 degrees C. The cementum cracked as the temperature increased. Certain cracked areas actually detached at 600 degrees C giving a corroded aspect to the cementum and the residual zones became irregular when the temperature rose and eventually at 1150 degrees C the cementum was no longer identifiable.

[Cleansing effect of two micromotor-driven endodontic handpieces.II. Effect of various rinsing solutions on the cleansing effect of the handpieces]. / Két, mikromotorral meghajtott endodontiai kézidarab tisztítóhatásának vizsgálata. II. rész. Különbözó átöblítófolyadékok alkalmazásának befolyása az egyes kézidarabokkal végzett tisztítás eredményességére.

The cleansing effectivity of citric acid solution was significantly better than that of Neomagnol both with respect to the removal of the Smear Layer (SL) and to the number of visible dentinal tubular orifices, however a complete elimination of the SL could not be obtained. Neomagnol seemed to be more effective in the removal of superficial debris and tissue-remnants.

[Comparison of the cleansing effect of two micromotor-driven endodontic hand pieces. I. Comparison ot the cleansing effect of the two handpieces]. / Két mikromotorral meghajtott endodontiai kézidarab tisztitó hatásának vizsgálata. I. rész. A két kézidarab tisztitó hatásának összehasonlitása.

The aim of the study was to assess the cleansing-effect of two endodontic handpieces (Excalibur, W & H; MM 1400 Micro Méga) in root canals that were previously manually prepared, and treated with chlor-(Neomagnol) and citric acid containing solutions. The analyses were performed by scanning electron microscope (SEM). The elimination of the Smear Layer (SL) with Neomagnol was not successful with either of the two handpieces. The cleansing of the Superficial Debris (SD) with Neomagnol activated by MM 1400 was significantly more effective in the apical (p < 0.05) and in the middle (p < 0.01) third of the root-canal, than by Excalibur. In contrast, SL was better eliminated by Excalibur using citric acid, significant differences--when compared with MM 1400--could be seen in the middle third (p < 0.05) of the root-canal. The handpieces seem to have their own specific characteristics: thus MM 1400 was better in eliminating the SD (used with Neomagnol), while Excalibur was superior in eliminating the SL (used with citric acid).