Evaluation of Dimensional Changes According to Aging Period and Postcuring Time of 3D-Printed Denture Base Prostheses: An In Vitro Study.

During the three-dimensional (3D) printing process of a dental prosthesis, using photopolymer resin, partially polymerized resin is further cured through the postcuring process that proceeds after the printing, which improves the stability of the printed product. The mechanical properties of the end product are known to be poor if the postcuring time is insufficient. Therefore, this study evaluated the effect of the postcuring time of the 3D-printed denture base on its dimensional stability, according to the aging period. The 3D prints were processed after designing maxillary and mandibular denture bases, and after the following postcuring times were applied: no postcuring, and 5, 15, 30, and 60 min. The dimensional stability change of the denture base was evaluated and analyzed for 28 days after the postcuring process. The trueness analysis indicated that the mandibular denture base had lower output accuracy than the maxillary denture base, and the dimensional stability change increased as postcuring progressed. In the no postcuring group for the mandible, the error value was 201.1 ± 5.5 µm (mean ± standard deviation) after 28 days, whereas it was 125.7 ± 13.0 µm in the 60 min postcuring group. For both the maxilla and the mandible, shorter postcuring times induced larger dimensional stability changes during the aging process. These findings indicate that in order to manufacture a denture base with dimensional stability, a sufficient postcuring process is required during the processing stage.

Assessment of Age-Related Changes on Masticatory Function in a Population with Normal Dentition.

This study aimed to investigate the influence of changes in age-related physiological muscular and dental factors on masticatory function. This study was conducted in 211 healthy participants divided into four different age groups: 20-45 years (Gr1); 45-60 years (Gr2); 61-70 years (Gr3); and ≥71 years (Gr4). For objective evaluation of masticatory function, the masticatory performance, bite force, posterior bite area (PBA), functional tooth units (FTUs), the number of remaining teeth, tongue pressure, masseter muscle thickness (MMT), and handgrip strength were examined. Food intake ability (FIA) and the Oral Health Impact Profile-14 score were assessed subjectively using questionnaires. A significant decrease in the number of remaining teeth, FTUs, handgrip strength, and FIA was found in Gr4, and a significant decrease in the tongue pressure, PBA, and bite force was found in those aged ≥61 years. In groups 1 and 3, an association of the PBA with masticatory performance was observed. However, there was no significant decreasing trend in the MMT with respect to masticatory performance with aging. With sufficient FTUs and posterior tooth support, although age-dependent decreases in the bite force, tongue pressure and handgrip strength were observed, masticatory performance was maintained. Establishing the PBA by improving occlusion through dental treatment is thought to be important for masticatory function.

Dental treatment under general anesthesia for patients with severe disabilities.

Patients with disabilities have difficulties tolerating in-office dental treatment due to limitations relating to cooperation and/or physical problems. Therefore, they often require general anesthesia or sedation to facilitate safe treatment. When deciding on dental treatment under general anesthesia, the plan should be carefully determined because compared to general patients, patients with disabilities are more likely to experience anesthetic complications because of their underlying medical conditions and potential drug interactions. Clinicians prefer simpler and more aggressive dental treatment procedures, such as extraction, since patients with impairment have difficulty maintaining oral hygiene, resulting in a high incidence of recurrent caries or restorative failures. This study aimed to review the available literature and discuss what dentists and anesthesiologists should consider when providing dental treatment to patients with severe disability under general anesthesia.

Foreign body aspiration during dental treatment under general anesthesia: A case report.

Foreign body aspiration in dental clinics is the most common cause of respiratory emergencies. There are no reports on foreign body aspiration during dental treatment under stable general anesthesia because the patient neither has voluntary movements nor reflex actions. This is a case report on the fall of a prosthesis in the larynx, which occurs rarely under general anesthesia. During the try-in procedure, the prosthesis slid from the surgeon's hand and entered the retromylohyoid space, and while searching for it, it passed down the larynx to the endotracheal tube balloon, leading to a dangerous situation. The prosthesis was promptly removed using video-assisted laryngoscope and forceps, and the patient was discharged without any complications.

Delayed paresthesia of inferior alveolar nerve after dental surgery: case report and related pathophysiology.

Paresthesia is an altered sensation of the skin, manifesting as numbness, partial loss of local sensitivity, burning, or tingling. The inferior alveolar nerve (IAN) is the third branch of the trigeminal nerve and is very important in dental treatment. IAN paresthesia may occur after various dental procedures such as simple anesthetic injections, surgical procedures, and endodontic treatment, and is reported to range from 0.35% to 8.4%. The altered sensation usually follows immediately after the procedure, and reports of late onset of nerve involvement are rare. This report presents a rare case of delayed paresthesia after dental surgery and discusses the pathophysiology of IAN delayed paresthesia.

Postoperative irradiation after implant placement: A pilot study for prosthetic reconstruction.

PURPOSE: On maxillofacial tumor patients, oral implant placement prior to postoperative radiotherapy can shorten the period of prosthetic reconstruction. There is still lack of research on effects of post-implant radiotherapy such as healing process or loading time, which is important for prosthodontic treatment planning. Therefore, this study evaluated the effects of post-implant local irradiation on the osseointegration of implants during different healing stages. MATERIALS AND METHODS: Custom-made implants were placed bilaterally on maxillary posterior edentulous area 4 weeks after extraction of the maxillary first molars in Forty-eight Sprague-Dawley rats. Experimental group (exp.) received radiation after implant surgery and the other group (control) didn't. Each group was divided into three sub-groups according to the healing time (2, 4, and 8 week) from implant placement. The exp. group 1, 2 received 15-Gy radiation 1 day after implant placement (immediate irradiation). The exp. group 3 received 15-Gy radiation 4 weeks after implant placement (delayed irradiation). RESULTS: The bone mineral density (BMD) was significantly lower in the immediate irradiation groups. BMD was similar in the delayed irradiation group and the control group. The irradiated groups exhibited a lower bone-to-implant contact ratio, although the difference was not statistically significant. The irradiated groups also exhibited a significantly lower bone volume and higher empty lacuna count than the control groups. No implant failure due to local irradiation was found in this study. CONCLUSION: Within the limits of this study, the timing of local irradiation critically influences the bone healing mechanism, which is related to loading time of prostheses.

Attitudes of Korean Dental Students Toward Individuals with Special Health Care Needs.

The purposes of this study were to ascertain the attitudes of dental students toward individuals with special health care needs (SHCNs) in Korea and to elucidate the characteristics associated with these attitudes. The authors recruited students from four of the 11 dental schools in Korea to participate in a survey; these schools were selected for regional balance. The Scale of Attitudes toward Disabled Persons (SADP) was used as the primary survey instrument, and ten independent variables were included. Of the 1,100 possible participants, 1,057 responded to the survey, for a response rate of 96.1%. The results showed that although the students' attitudes did not differ significantly by gender, their attitudes did show statistically significant differences on nine other variables: age, year, religion, self-esteem, friends with a disability, volunteering, admission course, concern for individuals with SHCNs, and intention to treat individuals with SHCNs (all p<0.05). The attitudes of these Korean dental students toward individuals with SHCNs were relatively unfavorable, showing lower SADP scores than reported in Western countries and likely reflecting Eastern cultural values in general. Future efforts should place greater emphasis on special care dentistry education and encourage the development of more favorable attitudes regarding the treatment of individuals with SHCNs.

Precise implant placement with a computer-assisted surgical guide in cleft lip and palate patients.

It is very common for cleft lip and palate patients to have congenitally missing teeth. Insufficient buccopalatal bone volume, a shallow vestibule, and lack of soft tissue resulting from previous surgical scarring render it difficult for clinicians to place implants in the missing area. This report describes guide surgery that represents a treatment option for cases in which implants need to be placed in tight spaces with minimal bone space, to minimize as far as possible manual placement errors.

Teriparatide therapy for bisphosphonate-related osteonecrosis of the jaw associated with dental implants.

This report describes a case of teriparatide (TPTD) therapy for bisphosphonate (BP)-related osteonecrosis of the jaw induced after implant placement. A 75-year-old woman taking oral BP was referred with uncontrolled osteonecrosis of the mandible related to the implant placement. With conservative treatment, BP was suspended and daily subcutaneous injections of 20 µm/d TPTD were started. After 4 months of the therapy, fixture removal and sequestrectomy were performed. Histological analysis revealed necrotic lamellar bone and empty osteocytic lacunae. In contrast, multiple irregular reversal lines of the lamellar bone and active osteoblasts were noted adjacent to the lesion. There was a significant increase in serum C-terminal telopeptide cross-link of type 1 collagen and serum osteocalcin after commencement of the therapy. After 7 months off therapy, the serum levels of the 2 markers remained at a high level compared with the baseline.

Full mouth rehabilitation of a patient with Sturge-Weber syndrome using a mixture of general and sedative anesthesia.

Issues related to the control of seizures and bleeding, as well as behavioral management due to mental retardation, render dental treatment less accessible or impossible for patients with Sturge-Weber syndrome (SWS). A 41-year-old man with SWS visited a dental clinic for rehabilitation of missing dentition. A bilateral port-wine facial nevus and intraoral hemangiomatous swollen lesion of the left maxillary and mandibular gingivae, mucosa, and lips were noted. The patient exhibited extreme anxiety immediately after injection of a local anesthetic and required various dental treatments to be performed over multiple visits. Therefore, full-mouth rehabilitation over two visits with general anesthesia and two visits with target-controlled intravenous infusion of a sedative anesthesia were planned. Despite concerns regarding seizure control, bleeding control, and airway management, no specific complications occurred during the treatments, and the patient was satisfied with the results.

Preservation of Hypermobile Teeth by Establishing Posterior Occlusal Support Using Implant Prostheses: A 5-Year Follow-Up.

For patients with periodontally compromised, hypermobile teeth, implant-supported fixed dental prostheses (FDPs) or removable dentures are often used after extracting mobile teeth. The loss of native teeth may carry social consequences, depending upon the patient's age, state of health, and degree of social functioning. This report represents successful stabilization and preservation of questionable, hypermobile teeth that have been damaged by traumatic occlusion due to the loss of posterior support with a cross-arch splinted FDP, as well as the implementation of posterior support using implant-supported prostheses.

Precise Implant Placement With a Computer-Assisted Surgical Guide in Cleft Lip and Palate Patients.

It is very common for cleft lip and palate patients to have congenitally missing teeth. Insufficient buccopalatal bone volume, a shallow vestibule, and lack of soft tissue resulting from previous surgical scarring render it difficult for clinicians to place implants in the missing area. This report describes guide surgery that represents a treatment option for cases in which implants need to be placed in tight spaces with minimal bone space, to minimize as far as possible manual placement errors.

Effect of premolar extraction and presence of the lower third molar on lower second molar angulation in orthodontic treatment.

OBJECTIVE: To evaluate the change in mandibular second-molar (M2) angulation in orthodontic treatment with premolar extraction and lower third molar (M3). STUDY DESIGN: Panoramic radiographs were evaluated in 3 groups of 129 participants: (1) control, no orthodontic treatment (n = 65); (2) extraction, orthodontic treatment with premolar extraction (n = 30); and (3) nonextraction, orthodontic treatment without premolar extraction (n = 34). The angular difference and ratio of M2 to the first molar (M1), the change in the angulation of M2 between pre- and postorthodontic treatment, and the distal bone level of M2 were assessed. RESULTS: The angular difference and ratio of M2 to M1, the angulation change of M2 between pre- and postorthodontic treatment, and the distal bone level of M2 were higher in the nonextraction group than in the control and extraction groups. CONCLUSIONS: The successful orthodontic alignment of the M2 may not be achieved in nonextraction cases when the M3s are present.

Implant displacement into the mandible: an unusual complication during implant surgery.

In contrast with problems regarding initial stability of dental implants in the posterior maxilla, heat generation during bone drilling is one of the complications that can occur in the mandible which is usually composed of dense bone. This report presents an unusual case of implant displacement into the mandibular posterior area of a middle-aged woman. This problem was presumably caused by poor bone density, loss of cortical bone engagement, and differences in bone quality between the alveolar bone and the basal bone.

Dislodgement resistance of modified resin-bonded fixed partial dentures utilizing tooth undercuts: an in vitro study.

STATEMENT OF PROBLEM: Over the years, resin-bonded fixed partial dentures (RBFPDs) have gone through substantial development and refinement. Several studies examined the biomechanics of tooth preparation and framework design in relation to the success rate of RBFPDs and considered retention and resistance form essential for increase of clinical retention. However, these criteria required preparations to be more invasive, which violates not only the original intentions of the RBFPD, but may also have an adverse effect on retention due to loss of enamel, an important factor in bonding. PURPOSE: The object of this in vitro study was to compare the dislodgement resistance of the new types of RBFPDs, the conventional three-unit fixed partial denture, and conventional design of RBFPD (Maryland bridge). MATERIAL AND METHODS: Fifty resin mandibular left second premolars and second molars were prepared on dentiforms, according to the RBFPD design. After model fabrication (five group, n = 10), prostheses were fabricated and cemented with zinc phosphate cement. After cementation, the specimens were subjected to tensile loading at a cross head speed of 4 mm/min in a universal testing machine. The separation load was recorded and analyzed statistically using one-way analysis of variance followed by Duncan's multiple range test. RESULTS: Group V, the pin-retained RBFPDs, had the highest mean dislodgement resistance, whereas specimens of group II, the conventional RBFPDs, exhibited a significantly lower mean dislodgement resistance compared to the other 4 groups (P < .05). There were no significant differences between group I, III, and IV in terms of dislodgement resistance (P > .05). Group V had the highest mean MPa (N/mm(2)) (P < .05). There was no significant difference between groups I, II, III and IV (P > .05). CONCLUSION: Within the limits of the design of this in vitro study, it was concluded that: 1. The modified RBFPDs which utilizes the original tooth undercuts and requires no tooth preparation, compared with the conventional design of RBFPDs, has significantly high dislodgement resistance (P < .05). 2. The modified RBFPDs which utilizes the original tooth undercuts and requires minimal tooth preparation, compared with the conventional FPDs, has significantly no difference in retention and dislodgement resistance)(P > .05). 3. The pin-retained FPDs showed a high dislodgement resistance compared to the conventional three-unit FPDs (P < .05).