Objectives: The aim of this study was to research radiologically for root resorption of mandibular second molars （second molars） appearing in association with impacted mandibular third molars （third molars）, the frequency of caries on second and third molars，and risk factors．

Materials and Methods: 224 third molars and 325 second molars in 224 patients aged 16 to 86 years were evaluated for inclination angle，status of impaction，and position of horizontal impaction of the third molars on panoramic radiographs，and for caries and root resorption on dental cone beam CT images. Root resorption and dental caries of second molars were defined as root resorption when the second molar was in contact with the third molar, and dental caries when the second molar was not in contact with the third molar. The depths of horizontal burial were classified as A, B, and C in order of superficiality.

Results: Root resorption of second molars, caries of second molars, and caries of third molars were observed in 40.9%, 13.5%, and7.6% of the patients, respectively. Root resorption of second molars according to age was most common in the age group of 16-39 years, with a frequency of 47.7%. In terms of inclination angle, root resorption at 60-74˚ was observed in 58.3%, second molar caries in 15.3%, and third molar caries in 11.1%. Root resorption of the second molar, caries of the second molar, and caries of the third molar were observed in 58.4%, 18.8%, and 12.2% of the horizontally buried teeth respectively, with root resorption being significantly more frequent （p=<0.05）. As for the depth of horizontal implantation, root resorption at depth A was observed in 47.6% of the cases.

Conclusion：When the third molar is inclined as much as 60-74˚ and is close to the neck of the second molar, root resorption of the second molar appears more frequently. Prophylactic extraction of the third molar is recommended in this condition to avoid root resorption of the second molar.

Young children possess a tendency to put various things that they see into their mouths. We report our experience with the case that accepted foreign body impaction to mandibular deciduous central incisor this time.

The case involved a girl aged two years nine months.

She fell down at the time for 1 year old six months. She reported unrest of the lower jaw deciduous anterior teeth and pain from the time for 2 years old five months. It was intraoral findings, and the cervix of the mandibular left deciduous central incisor showed a milk-white structure, and the X-rays findings showed circumference resorption of the alveolar bone, but there was no non-transmission increase to agree with an opalescence structure. We judged the milk-white structure with the foreign body which we invaginated by a fall accident and resected it. The foreign body which we resected was a straw state. After continuing following it up after the foreign body removal regularly, we showed the addition of the alveolar bone and showed improvement of the paradental condition. The foreign body impaction example makes a correct decision immediately, and it is necessary to remove the foreign body. Also, it is desirable to conduct a tendency of the paradentium to recovery, the symptom confirmation to an affected tooth after the removal in the long term. In addition, it is necessary to spread the spread of knowledge for the accident to occur by infants putting a foreign body in the oral cavity for a protector and a person concerned with childcare more than before.

The demand to implement patient safety policy in primary care has increased. When patients are at home, the patient/patient’s family bears the responsibility of medical management to an extent that is greater than what they are required to do during hospitalization. In addition, since primary care organizations tend to be small, human resource shortages can easily occur. Moreover, there are some problems like the educational plan and career establishment. Despite these limitations, primary care providers have to implement quality management to ensure patient safety. Primary care is expanding to encompass activity fields such as community cooperation and collaboration between medical and dental fields. In addition, due to improvements in primary care, the length of hospital stay has shortened; even patients with severe medical management are discharged directly from hospital to home. There is an incident was occurring which was the characteristic of primary care, which included some events that are reported the patient death. For keeping patient safety, it is important to also maintain health worker safety.

The number of cases of fixed implant support prosthesis and implant overdenture as one of the options for missing teeth is steadily increasing, and it is expected that the number of elderly people who have received dental implant treatment will also steadily increase. It is essential to consider treatment options for the elderly who have received dental implants. In this report, dental implant cases were presented and considered how to deal with elderly people who have received implant treatment.

Case 1: A practitioner was performing occlusal reconstruction with dental implants. A few years later, comprehensive treatment involving removal of dental implant was required.

Case 2: A fixed implant-supporting prosthetic superstructures were received to an elderly patient aged over 80 years old who had a decrease in masticatory function due to non-vertical stop occlusion.

In cases where full mouth dental implant treatment has been performed, treatment by dental visit may be the most difficult. In such cases, it is very important to transfer the implant superstructure from the fixed prosthesis to the removable prosthesis when the patient is healthy. In addition, when implant treatment is performed in the elderly, so the time to replace the fixed prosthesis with the removable prosthesis should be decided in advance with the patient. This is because the removable prosthesis device makes it easier to handle in dental visit. When performing dental implant treatment, such a situation should be assumed in advance and implant treatment should be performed