Introduction: Cracked tooth syndrome is defined as an incomplete fracture initiated from the crown and extending cervically, and sometimes gingivally, and is usually directed mesiodistally. Objective: To analyze the literature about cracked tooth syndrome, its etiology, prevalence, pulp involvement and treatment. Methodology: Using the keywords "cracked tooth syndrome", "etiology", "prevalence", "pulp involvement" and "treatment", the MEDLINE/PubMed and ScienceDirect databases were searched, with emphasis on the last 5 years. It was evaluated with the PRISMA and AMSTAR-2 guidelines. Results: There are many causes for cracks, the main one being malocclusion. Another is due to restorations, pieces to which amalgam was placed due to the extension of the cavity for the retentions. The second lower molar presents more frequently fissures due to premature contact. Cracked teeth are a challenge for the dentist in the diagnosis since the discomfort is presented with different stimuli. Depending on the extent of the fissure, the treatment is decided, always keeping in mind that the prognosis is reserved. Conclusions: Cracked tooth syndrome will always be a challenge for the dentist at the time of diagnosis and treatment. There is no specific treatment, depending on the extent of the fissure is to decide the treatment to be performed.

Athletes are exposed to trauma that can sometimes involve the oral cavity from an injury, fracture or dental loss. Many times aware or not that it is an own risk that represents practicing a certain sport but its vocation is greater regardless of the consequences. Objective. To determine the prevalence of dental trauma in athletes between 16-30 years of the gymnasium Institute Veracruzano of sport. Methodology Observational, cross-sectional and prospective study in a sample of 43 athletes applying a survey of 15 questions to athletes from the Institute Veracruzano of sport gymnasium. Contribution. The dental injuries found in this research were low, however, athletes should be educated in the protection of accidents through the appropriate equipment including the mouth, implementing mandatory preventive measures not before raising awareness about oral health care. Currently, dental injuries are the second cause of attention in emergency services in dentistry after caries.

Saliva is multifunctional: cleaning of the oral cavity, lubrication, preservation, repair of mucous membranes and dental hard tissues; the pH and its buffering, also participates in the elimination of bacteria, digestion and speech. The salivary composition in gestational period is altered, with variation of salivary pH and buffer capacity. Objective. To determine the levels of pH and salivary flow that prevail in pregnant patients. Methodology. Descriptive, prospective and transversal study. Sampling for convenience: pregnant patients in the 1st, 2nd and 3rd trimesters who attended the UMF. 61 to medical control of their pregnancy. Using a calibrated JENWAY 3510 Ph Meter potentiometer. Saliva samples were collected at least one hour after eating. Contribution. The salivary pH in pregnant women is lower in the first quarter than in later ones. According to Spearman's test analysis, a positive correlation is reported (r2 = 0.34), the correlation of ranges between pH and salivary volume is statistically significant even if it is weak. The salivary pH is lower in the first quarter than in the two subsequent ones, the salivary flow does not vary significantly in the first and second quarters, but it increases in the third quarter.

The jaw is articulated with the skull through the temporomandibular joint. And the skull, in turn articulates with the spine (upper cervical). Important studies establish that up to 30-40 % of back pain can be caused or aggravated by dental malocclusion. Objective. To establish the types and frequency of body postures and dental malocclusions in the patients of the School of Dentistry in the period August-December 2019. Methodology. Transversal, descriptive and observational study. The sample was made up of a total of 50 patients between the ages of 19 and 70 who attended the Admission Clinic of the School of Dentistry. To which were carried out: verification of molar class, verification of midline deviation, verification of posterior crossbite, external lateral palpation of the TMJ, extraoral photographs, analysis of photographs. Contribution. It was found that there is a high frequency of one type of body posture and Angle Class I malocclusions, in patients from the School of Dentistry. In relation to malocclusions, Angle Class I predominated, as well as flattened posture, in Class II military posture and in Class III both flattened and military posture.

Peroxides are currently the most widely used products for tooth whitening, when peroxide decomposes it produces a decrease in the pH in the medium in which it is found, immediately in the enamel produces acid etching that varies depending on the pH of the product, contact time and concentration. Objectives: To know the effect of hydrogen peroxide at 35% on dental microhardness. Methodology: Experimental, transversal, descriptive study. Using 50 teeth that were cut 1 mm below the amelocemental junction to create two vestibular and palatal faces. The teeth were lightened with 35% hydrogen peroxide to find out how much micro-hardness the enamel loses, the Vickers unit of measurement. The microhardness was measured after making 3 indentations in different surfaces of the enamel at a force of 50 grams and a time of 20 seconds with a diamond tip that left a trace observed under the microscope in the form of a pyramidal diamond; based on the vertical and horizontal diagonals, the Vickers microhardness was determined. Contribution: According to the results obtained, we found that the application of 35% hydrogen peroxide decreased dental microhardness by 25.08%.