In vivo clinical and histological thermal effect of a 445 nm diode laser on oral soft tissues during a biopsy

Maxillary labial frenectomy: a randomized, controlled comparative study of two blue (445 nm) and infrared (980 nm) diode lasers versus surgical scalpel

BACKGROUND

This study aimed to compare the intra and postoperative complications of frenectomy procedure with a surgical scalpel versus 445 nm and 980 nm diode lasers.

METHODS

This randomized controlled clinical trial was conducted on 174 patients requiring maxillary labial frenectomy. After completion of fixed orthodontic treatment and primary closure of maxillary diastema, the patients were randomly assigned into three groups (n = 58): group 1 (frenectomy via 445 nm diode laser, continuous-wave, 1.5 W), group 2 (frenectomy via 980 nm laser, continuous-wave, 1.7 W), and control group (V-Y plasty technique via scalpel). Intra-operative bleeding, discomfort in chewing and speaking, pain, and tissue healing were compared among the groups immediately, at 7 and 30 days postoperatively using the Kruskal-Wallis, Mann-Whitney, and Chi-square tests.

RESULTS

Pain scores were significantly lower in group 1 compared to group 2 (immediately and day 7, P < 0.05). Significant faster tissue healing at days 7 and 30 were observed in group 1 compared to group 2 (P < 0.05). Group 1 was superior to the control group regarding lower intraoperative bleeding, discomfort in chewing and speaking (immediately and day 7), lower pain (immediately and day 7), and tissue healing (day 7) (P < 0.05 for all). Group 2 was significantly superior to the control group in lower intraoperative bleeding, discomfort in chewing and speaking (immediately and day 7), and better tissue healing (day 7) (P < 0.05 for all).

CONCLUSIONS

In conclusion, diode laser frenectomy resulted in significantly lower intra and postoperative complications compared to the scalpel. Moreover, 445 nm diode laser showed significantly superior effects compared to 980 nm diode laser.

TRIAL REGISTRATION

The study protocol was registered on 29.10.2022 at the Iranian Registry of Clinical Trials ( www.irct.ir ) (registration number: IRCT20220630055326N1).

The features of the reparative regeneration of an oral mucosa wound created under the exposure of a laser at a wavelength of 445 nm (a pilot study)

In clinical practice, an innovative laser technology that provides contactless preparation of soft tissues with a wavelength of 445 nm has been introduced. This study aimed to investigate the morphological changes in the oral mucosa when exposed to laser radiation at a wavelength of 445 nm in the ablation mode.An experimental study was conducted to analyze the dynamics of reparative regeneration in the wound caused by that particular type of radiation, utilizing the procedure of lower lip frenuloplasty as an illustration. 48 sexually mature male laboratory rats were chosen as the research object. The procedure of preparing the oral vestibule was executed by employing a contactless laser beam with a wavelength of 445 nm and a power of 0.7 W in continuous mode (CW) and an uninitiated fiber.Histological examination showed that 25 min after the surgery, there were large areas of coagulation necrosis in the oral mucosa in the area affected by the blue laser. In 48 h, the area of necrosis decreased both in size and depth. By the 7th day after the surgery, the necrotic masses had grown into the connective tissue, while marginal regeneration of the epithelium was noted. By the 14th day, the wound surface was completely epithelialized, represented by fibrous scar tissue. Clinically, around the mandibular incisors, there was a wide area of attached keratinized gingiva.The findings of histological examination indicate a necrosis of coagulation type in the region of tissue ablation and also show the absence of phase II of the inflammatory response (the stage of exudation), which expedites the process of epithelialization of the oral mucosa wound.

Symphyseal-Sparing Mandibulectomy for Canine Acanthomatous Ameloblastoma in Dogs: 35 Cases

Canine acanthomatous ameloblastoma (CAA) has been reported to be the most prevalent odontogenic tumor in dogs. The most common location of this tumor is the rostral mandible. Symphyseal-sparing mandibulectomy has been shown to be an effective technique to maintain mandibular continuity and promote early return to function. In this retrospective study, 35 dogs with CAA associated with a mandibular canine tooth were evaluated following a symphyseal-sparing rostral mandibulectomy. Dogs with intraoperative transection of the canine tooth root and subsequent root fragment extraction were included. The objective of this study was to evaluate outcome following excision of CAA with mid-root transection. Data retrospectively evaluated in this study included the following: narrowest tumor margin, narrowest tumor margin at the border associated with the transected canine root, tumor size, and prevalence of local recurrence. This study showed that 82.86% of CAA were completely excised with tumor-free margins (N = 29). The median narrowest overall tumor-free margin was 3.5 mm (interquartile range [IQR] 2.0-6.5 mm) and the median tumor-free margin associated with the border of the transected canine root was 5.0 mm (IQR 3.1-7.0 mm). Follow-up data was obtained in 25 cases via phone interviews with referring veterinarians and clients. No local tumor recurrence was reported in cases with incomplete tumor excision (N = 5). All dogs with follow-up data survived at least 1 year following surgery. It was concluded that segmental or rostral mandibulectomy with wide margins to include the entire mandibular canine tooth with subsequent mandibular instability may not be warranted for dogs with CAA associated with this tooth.

Accident due to Incorrect Selection of Diode Laser Technique in the Treatment of Oral Venous Malformation

Venous malformation (VM) originates from a congenital venous network disorder, configuring about 40% of the vascular anomalies that occur in the head and neck region. The usage of diode lasers in the treatment of VM is associated with various advantages, such as short operating time and few postoperative complications. Nevertheless, for larger and deeper VM treatment, it may require more than one session for the complete resolution of the lesion. Laser surgery for oral VM may induce heat accumulation due to excessive irradiation causing adverse events postoperatively, including pain and ulcer formation with scarring. In this clinical case, it was recommended to use the leopard technique (LT) to reduce the lesion size, evaluate the remaining unhealed lesion, and apply different laser techniques to obtain the complete resolution of the lesion.

SEM Evaluation of Thermal Effects Produced by a 445 nm Laser on Implant Surfaces

The aim of this in vitro study was to evaluate thermal effects on implant surfaces using a 445 nm diode laser (Eltech K-Laser Srl, Treviso, Italy) with different power settings and irradiation modalities. Fifteen new implants (Straumann, Basel, Switzerland) were irradiated to evaluate surface alteration. Each implant was divided into two zones: the anterior and posterior areas. The anterior coronal areas were irradiated with a distance of 1 mm between the optical fiber and the implant; the anterior apical ones were irradiated with the fiber in contact with the implant. Instead, the posterior surfaces of all of the implants were not irradiated and used as control surfaces. The protocol comprised two cycles of laser irradiation, lasting 30 s each, with a one-minute pause between them. Different power settings were tested: a 0.5 W pulsed beam (T-on 25 ms; T-off 25 ms), a 2 W continuous beam and a 3 W continuous beam. Lastly, through a scanning electron microscopy (SEM) analysis, dental implants' surfaces were evaluated to investigate surface alterations. No surface alterations were detected using a 0.5 W laser beam with a pulsed mode at a distance of 1 mm. Using powers of irradiation of 2 W and 3 W with a continuous mode at 1 mm from the implant caused damage on the titanium surfaces. After the irradiation protocol was changed to using the fiber in contact with the implant, the surface alterations increased highly compared to the non-contact irradiation modality. The SEM results suggest that a power of irradiation of 0.5 W with a pulsed laser light emission mode, using an inactivated optical fiber placed 1 mm away from the implant, could be used in the treatment of peri-implantitis, since no implant surface alterations were detected.

The Impact of Laser Thermal Effect on Histological Evaluation of Oral Soft Tissue Biopsy: Systematic Review

The aim of the study is to review the literature to observe studies that evaluate the extent of the thermal effect of different laser wavelengths on the histological evaluation of oral soft tissue biopsies. An electronic search for published studies was performed on the PubMed and Scopus databases between July 2020 and November 2022. After the selection process, all the included studies were subjected to quality assessment and data extraction processes. A total of 28 studies met the eligibility criteria. The most studied laser was the carbon dioxide (CO₂) laser, followed by the diode laser 940 nm-980 nm. Six studies were focused on each of the Erbium-doped Yttrium Aluminium Garnet (Er:YAG), Neodymium-doped Yttrium Aluminum Garnet (Nd:YAG) lasers, and diode lasers of 808 nm and 445 nm. Three studies were for the Potassium Titanyl Phosphate (KTP) laser, and four studies were for the Erbium, Chromium-doped Yttrium, Scandium, Gallium, and Garnet (Er,Cr:YSGG) laser. The quality and bias assessment revealed that almost all the animal studies were at a low risk of bias (RoB) in the considered domains of the used assessment tool except the allocation concealment domain in the selection bias and the blinding domain in the performance bias, where these domains were awarded an unclear or high score in almost all the included animal studies. For clinical studies, the range of the total RoB score in the comparative studies was 14 to 23, while in the non-comparative studies, it was 11 to 15. Almost all the studies concluded that the thermal effect of different laser wavelengths did not hinder the histological diagnosis. This literature review showed some observations. The thermal effect occurred with different wavelengths and parameters and what should be done is to minimize it by better adjusting the laser parameters. The extension of margins during the collection of laser oral biopsies and the use of laser only in non-suspicious lesions are recommended because of the difficulty of the histopathologist to assess the extension and grade of dysplasia at the surgical margins. The comparison of the thermal effect between different studies was impossible due to the presence of methodological heterogeneity.