ABSTRACT
The word "laser" is an acronym for Light Amplification by Stimulated Emission of Radiation. These words define the unique qualities of lasers, whose application in the dental field focuses on dental therapy, aesthetic dentistry, prosthetics, and oral and periodontal surgery. Through this literature review, the application of lasers in dental clinical practice and its relevant parameters will be evaluated from a bioengineering perspective. Bioengineering can serve as a transdisciplinary bridge between engineering and dentistry, which is refined in the use of lasers to enhance the oral health of patients.

ABSTRACT
Introduction: Skeletal unit growth may be due to epigenetic influence exerted by the functional matrix on the skeleton. Penn analysis is a method used to evaluate tomographically the transverse alterations of the maxilla. Objective: To analyze the association between transverse collapse of the maxilla and facial biotype in patients of the Polyclinic of the Orthodontics Postgraduate Program of the Autonomous University of Baja California, Mexicali campus. Materials and methods: An observational, analytical and cross-sectional study was carried out. The sample consisted of 75 patients who met the inclusion criteria. Initial tomographic studies were used to determine the presence of transverse collapse by means of Penn analysis. Lateral skull teleradiographs were plotted to determine the facial biotype by means of the Vert coefficient of Ricketts' lateral cephalometric analysis. The chi-square test was performed for statistical analysis of the association between the presence of transverse collapse of the maxilla and facial biotypes. Results: No significant results were found between the chi-square values and the p-value for patients with transverse collapse of the maxilla in association with facial biotypes. However, a statistical chi-square value of 4.8422 and a p-value of 0.2777 were obtained for the sample of female patients with transverse collapse of the maxilla. Conclusions: No association was found between the presence of maxillary transverse deficiencies and facial biotypes.

ABSTRACT
The aim of this study was to determine whether the intensity of preoperative pain was a predictive factor for the prevalence and intensity of postoperative pain, considering demographic and clinical variables. The study involved́ 80 teeth with pulpal or periapical pathologies. Root canal treatment was performed in one or two sessions. Pain intensity was assessed using the visual analogue scale before treatment and then 6h, 12h, 24h, 48h, 72h and one week after root canal treatment. The sample consisted of 46 women and 34 men. This study showed́ that postoperative pain was statistically associated with female gender (p=0.05), tooth types (p=0.006), and its location on the mandibular arch (p=0.03). The main finding was that patients with a higher intensity of pre-operative pain had a higher incidence of post-operative pain (p<0.05). In the group of patients who had no pre-operative pain, 63% (17/27) of patients remained asymptomatic after root canal treatment, while only 7.4% (2/27) had severe post-operative pain with a significant difference (p<0.05). However, in the group with severe pre-operative pain, 100% of patients had post-operative pain, of which 75% (15/20) of patients had high levels of pain requiring analgesics.

ABSTRACT
Objective: To evaluate the quality of the services provided by the dental clinics of the Autonomous University of Baja California (UABC) Otay-Tijuana Campus using the Donabedian and SERVPERF methodologies to know strategies that allow improving the quality of care. Methodological design: A prospective cross-sectional study was carried out in a random sample of 1,315 surveys of patients who attended the clinics of the Tijuana Faculty of Dentistry of the UABC in the period 2023-1. To collect the information, the PERCACEL tool was used, developed using the Donabedian and SERVPERF methodologies, which consists of 4 sections: 1) Specifications of the clinic that provided the service and time in which the care was received, 2) General data of the respondent, 3) Perceptions of the care received and 4) User perception of the service provided. This survey was validated in the city of Puebla to be used in dental care clinics, obtaining a Cronbach's Alpha of 0.923 for the Donabedian instrument and 0.963 for the SERVPERF instrument. Results: The average of the evaluation obtained from the perception of quality through the SERVPERF model was 9.13, slightly higher than that obtained through the Donabedian model, which was 8.98, demonstrating that the quality of care provided by the university community is high without great variations.

ABSTRACT
Aim: To determine the effect of ethylenediaminetetraacetic acid (EDTA), lactic acid and citric acid on root dentin microhardness. Materials and Methods: In this in vitro study, twenty freshly extracted anterior teeth were transversely sectioned at the level of cementoenamel junction. The middle third of each root is then horizontally sectioned into slices that are 4 mm thick to obtain a total of 20 dentin discs. Based on the chelating agent used, the samples were randomly divided into four groups- saline (control group), 17% EDTA, 20% lactic acid and 10% citric acid. Vicker’s indenter was used to test the microhardness of the dentin before and after treatment with the chelating agents for two minutes. Data was obtained and statistically evaluated using a one-way analysis of variance (ANOVA), paired – t test and Tukey’s post hoc test. Results: The microhardness values varied significantly among the groups. Citric acid and and lactic acid were less effective at reducing dentin microhardness. EDTA led to a higher reduction in microhardness. Conclusion: All the chelating solutions reduced the microhardness. Lactic acid showed less alteration in the hardness of root dentin than EDTA.

ABSTRACT
Objective: The purpose of this study was to assess 6th year students' attitudes and perceptions towards problem-based learning sessions during their clinical internship. Methods: A cross-sectional study was conducted among undergraduate dental students at the hospital Farhat Hached Sousse in Tunisia from February to August 2023. Use questionnaires to survey students' attitudes and perceptions about problem-based learning sessions. Data were analyzed using SPSS 21. Results: 6th year dental students reported positive attitudes toward all programs, including self-directed learning, critical thinking, integrating fundamental concepts into clinical science, identifying knowledge gaps, and improving problem-solving skills. Conclusions: Most undergraduate students preferred PBL and felt it should be included in the curriculum along with other teaching methods.

ABSTRACT
Sialolithiasis is the most common disease of salivary glands. Its estimated frequency is 1.2% in the adult population. Sialoliths most commonly occur in the submandibular glands. A history of pain or/and swelling in the salivary glands, especially during meal suggests this diagnosis. For small and accessible stones conservative therapies like milking of ducts with palliative therapy can produce satisfactory results. Surgical management should be considered when the stone/stones are inaccessible or large in size as conservative therapies turned out to be unsatisfactory. In this paper, we present a case of 55-year-old male patient resenting painful swelling and a giant submandibular gland sialolith. The sialolith usually measures from 1 to <10 mm. Giant Sialoliths are classified as those exceeding 15 mm in any one dimension. This case report describes a patient presenting with an unusually large sialolith (megalith), which was in size 2.5 x 3cm, the subsequent patient management, etiology, diagnosis, and treatment.