Factors associated with age-related changes in oral diadochokinesis and masticatory function in healthy old adults.

BACKGROUND: This cross-sectional study aimed to identify factors associated with age-related changes in masticatory performance (MP) and oral diadochokinesis (ODK) and to provide normal values in healthy old adults for the diagnosis of oral frailty. METHODS: A total of 385 participants were divided into three age groups (Gr1-3): 20-64 years, 65-74 years, and ≥ 75 years. To investigate tongue-lip motor function, ODK was assessed as the number of repetitions of the monosyllables /pa/ta/ka/. Four questionnaires were used to assess subjective masticatory ability, cognitive ability, and psychological status. MP, bite force, and occlusal area were tested to assess dynamic objective masticatory function, and the number of remaining teeth and functional tooth pairs were determined to assess static objective masticatory function. Handgrip strength (HG), oral dryness, and tongue pressure (TP) were assessed to identify influencing factors. Intergroup differences were evaluated by ANOVA and the Kruskal‒Wallis test, and correlations between ODK and orofacial factors were evaluated. RESULTS: This study revealed significant age-related declines in TP, HG, and ODK, especially after 65 years of age. Factors affecting MP were posterior teeth, the Eichner index, bite force, occluding area, the Korean Mini-Mental State Examination (KMMSE) score, and ODK. Each ODK syllable was associated with different factors, but common factors associated with ODK were MP, HG, and PHQ-9 score. For the syllables /pa/ta/, the Eichner Index, TP, and oral dryness were also associated. For the syllable /ka/ in Gr3, MP, TP, HG, oral dryness, and the KMMSE score were associated. CONCLUSIONS: These results could provide practical guidelines for oral rehabilitation in old adults and contribute to improving the understanding of age-related changes in oral function and the multidimensional nature of masticatory dynamics.

The effect of surface treatment and low-temperature degradation on flexural strength of additive manufactured zirconia.

This study aimed to assess the effect of low-temperature degradation (LTD) and surface treatment on the flexural strength of additive-manufactured (AM) zirconia by comparison to subtractive-manufactured (SM) zirconia. Disc-shaped zirconia specimens were fabricated using AM and SM technology, and each group was assigned to 3 subgroups according to the type of surface treatment: control, sandblasting (SB), and 9% hydrofluoric acid etching (HF). The groups were then further divided into 2 subgroups: unaged and aged. Biaxial flexural strength, crystal phase, surface topography, and surface roughness were measured to evaluate the mechanical properties. Statistical analyses were performed with 3-way ANOVA, followed by the comparison of means with Bonferroni post hoc analyses. The means and standard deviations of the biaxial flexural strength and Weibull parameters were calculated with descriptive statistics. All SM groups showed significantly greater flexural strength than the AM groups (p < .05), and LTD did not affect flexural strength except for the SMHF group (p < .05). After LTD, monoclinic phases (m-phase) were found in all groups, and SEM images showed grain pullout due to zirconia volume expansion in both control groups. Sandblasting significantly affected flexural strength (p < .05), whereas the HF group did not affect flexural strength except in the SMHF group after LTD (p < .05). No significant difference was observed in the surface roughness of AM compared to SM groups conditioned with the same surface treatment regardless of LTD. AM zirconia has comparable mechanical properties to SM zirconia, regardless of low-temperature degradation and surface treatment, which indicates the potential of the AM technique for clinical applications.

Medication-related osteonecrosis of the jaw using periodontitis-induced rat before tooth extraction.

OBJECTIVE: This study aimed to investigate the occurrence of medication-related osteonecrosis of the jaw (MRONJ) after tooth extraction due to periodontitis in ovariectomized rats. METHODS: Twenty-four osteoporosis-induced rats were administered with zoledronic acid (ZA; ZA group) or saline (CONT group). In both groups, tooth extraction was performed after inducing periodontitis, and all animals were sacrificed 8-week after tooth extraction. RESULTS: Micro-CT of the tibia showed that the bone volume fraction, bone surface density, trabecular number, and bone mineral density were significantly higher in the ZA group than in the CONT group. Histologically, the proliferative zone on the growth plate was thicker in the ZA group than in the CONT group. Micro-CT of the extraction sites revealed that the bone volume fraction was significantly higher in the ZA group than in the CONT group. Radiologically, the ZA group showed partial healing and delayed healing. Histological analysis revealed normal bone healing status with completely healed epithelium in the extraction sites of the CONT group, whereas abnormal empty osteocytes in the necrotic bone and inflammatory infiltration were observed in the ZA group. CONCLUSION: The incidence of MRONJ increased in the rats administered with ZA.

Mechanical properties of additively manufactured zirconia with alumina air abrasion surface treatment.

This study aimed to evaluate the mechanical properties of zirconia fabricated using additive manufacturing technology and compare them to those of zirconia fabricated using subtractive manufacturing technology. Sixty disc-shaped specimens were fabricated for the additive (n = 30) and subtractive manufacturing groups (n = 30), and each group was divided into two subgroups according to their air-abrasion surface treatment: control (n = 15) and air-abrasion groups (n = 15). Mechanical properties including the flexural strength (FS), Vickers hardness, and surface roughness were determined, and the values were analyzed by one-way ANOVA and Tukey's post hoc test (α = 0.05). X-ray diffraction and scanning electron microscopy were used for phase analysis and surface topography evaluation, respectively. The SMA group exhibited the highest FS (1144.97 ± 168.1 MPa), followed by the SMC (944.58 ± 141.38 MPa), AMA (905.02 ± 111.38 MPa), and AMC groups (763.55 ± 68.69 MPa). The Weibull distribution showed the highest scale value (1213.55 MPa) in the SMA group, with the highest shape value in the AMA group (11.69). A monoclinic peak was not detected in both the AMC and SMC groups, but after air abrasion, the monoclinic phase content ([Formula: see text]) reached 9% in the AMA group, exceeding that in the SMA group (7%). The AM groups exhibited statistically lower FS values than those of the SM groups under the same surface treatment (p < 0.05). Air-abrasion surface treatment increased the monoclinic phase content and FS (p < 0.05) in both the additive and subtractive groups, while it increased the surface roughness (p < 0.05) only in the additive group and did not affect the Vickers hardness in either group. For zirconia manufactured using additive technology, the mechanical properties are comparable to those of zirconia manufactured using subtractive technology.

Importance of Photography Education to Improve Image Quality for Accurate Remote Diagnoses in Dental Trauma Patients: Observational Study.

BACKGROUND: High-quality photos are critical for the remote diagnosis of dental trauma and thus are beneficial to the prognosis. The quality of the images obtained using a cell phone depends on the level of dental and photography knowledge of the person who is taking the photos. OBJECTIVE: This study aimed to determine the efficacy of photography education in improving images used for the remote diagnosis of dental trauma. METHODS: The subjects comprised 30 laypeople and 30 dentists who were randomly assigned to 15 subgroups with 2 subjects in each. Each subject was asked to take photos of their own anterior teeth and those of their partner on the assumption that an accident occurred using both an iPhone 4s and iPhone 6. Education about how to take an appropriate photo of the anterior teeth for teleconsultation purposes was then provided, after which photos were taken again. Photos were assessed by a dentist for their usefulness in diagnosis. RESULTS: This study analyzed 965 photos: 441 taken by laypeople and 524 taken by dentists. Photos taken after providing education had significantly higher scores for all assessment items than those taken before education (P<.05). The scores were also significantly higher for photos taken using the rear camera than those taken using the front camera (P<.02). The iPhone 6 did not have overwhelming advantages. The photos taken by dentists had significantly higher scores than those taken by laypeople for most of the evaluated items. CONCLUSIONS: Both laypeople and dentists might find photography education useful for when they are taking photos to be used in teleconsultations. The type of cell phone does not significantly affect the usefulness of such photos.

Comparison of Self-Etching Ceramic Primer and Conventional Silanization to Bond Strength in Cementation of Fiber Reinforced Composite Post.

Various mechanical and chemical surface treatments have been proposed to improve the retention of fiber-reinforced composite post (FRCP), but the results are still controversial. The bond strength and durability of a self-etching ceramic primer, which was recently released as an alternative to etching and silane, are not yet known. This study aimed to compare and evaluate the push-out bond strength of different surface treatments of FRCPs after an artificial aging procedure. Four groups (n = 10) were established to evaluated FRCP surface treatments (dentin adhesive bonding; silane and adhesive bonding; hydrofluoric acid, silane and adhesive bonding; and a self-etching ceramic primer). They were bonded with dual-curing rein cement (Multilink N) and stored in distilled water at 37 °C for 30 days, then thermal cycled for 7500 cycles. After being sectioned into 1 mm thickness, each coronal and apical part was evaluated for its the push-out bond strength by a universal testing machine. Each debonded specimen was observed by an optical microscope and divided according to the failure modes. The results showed that silane treatment significantly improved push-out bond strength, but the self-etching ceramic primer did not do so. Additional hydrofluoric acid treatment or the adhesive bonding agent alone did not significantly improve the retention of FRCPs. Cohesive failure of the luting material was found most frequently in all groups.

Outcomes of autotransplanted teeth and prognostic factors: a 10-year retrospective study.

OBJECTIVES: This retrospective study aimed to investigate the clinical outcome of tooth autotransplantation and related prognostic factors. MATERIALS AND METHODS: Eighty-two cases of transplanted teeth from March 2006 to December 2016 were retrospectively investigated by medical records and radiographs. The clinical outcomes of transplanted teeth, which included tooth survival, inflammatory root resorption (IRR), ankylosis, and marginal bone loss (MBL), and the related prognostic factors were assessed via survival analysis. RESULTS: The cumulative survival rate of transplanted teeth was 74% at 10 years after autotransplantation. According to Cox proportional hazards regression analysis, the eruption state of the donor tooth, recipient position, and postoperative MBL were significantly related to tooth survival. The donor tooth position was significantly associated with IRR, the recipient position and the timing of orthodontic initiation with ankylosis, and the recipient position with MBL. CONCLUSIONS: Fully erupted donor teeth and a bounded recipient site were significantly associated with longer tooth survival. Periodontal healing and management to prevent postoperative MBL were as important for successful autotransplantation. CLINICAL RELEVANCE: Knowledge about the prognostic factors that are significantly associated with each particular clinical outcome may guide clinicians to achieve predictable and successful outcomes after tooth transplantation.

Clinical application of 3D technology for tooth autotransplantation: A case report.

This report presents two cases of tooth autotransplantation using cone-beam computed tomography (CBCT), the three-dimensional (3D) simulation dental planning software and a computer-aided rapid prototyping (CARP) model. Two hopeless teeth of adult patients were replaced as their third molar teeth. Before deciding the autotransplantation, diagnostic CBCT images were acquired and imported to SimPlant software. The SimPlant dental program was used for surgical simulation prior to autotransplantation, which created 3D images of the available donor teeth and recipient site tooth and superimposed the images to display their morphological similarity. Efficient modification of the recipient socket was designed preoperatively. The CARP model of the donor tooth was prepared as a substitute for the donor tooth that would be fit into the new recipient socket during bone preparation. Autotransplantation was favourably performed in 5-6 min. Transplanted teeth healed up without clinical abnormality. The postoperative follow-up time was up to 6 years.

Prevalence of proximal contact loss between implant-supported fixed prostheses and adjacent natural teeth and its associated factors: a 7-year prospective study.

OBJECTIVES: The aim was to analyze the prevalence rate of proximal contact loss (PCL) between implant-fixed prostheses (IFPs) and adjacent teeth and investigate the associated factors. MATERIAL AND METHODS: One hundred fifty participants were recruited for this prospective study from January 2009 to December 2014. Two hundred thirty-four IFPs supported by 384 implants for the posterior region were followed up until June 2016. The contact tightness had been recorded using aluminum strips of different thicknesses with a regular interval after delivery. Proximal contact was considered as lost if the contact tightness was over 50 µm, and statistical analyses were performed to estimate the prevalence rate of PCL and its influential factors. RESULTS: Among the total 299 proximal contacts of 234 IFPs, 179 were observed as a PCL (59.9%). Bone level and root configuration of the adjacent teeth, the proximal contact position and jaw position of the implant prostheses were statistically significant factors, when analyzed by the cumulative PCL rate using the log-rank test of the Kaplan-Meier method (P < 0.05) According to the Cox proportional hazard regression analysis, the proximal contact position, bone level of adjacent teeth and jaw position were revealed to be statistically significant (P < 0.05). CONCLUSION: PCL should be considered an implant prosthesis complication to which various associated factors could be related. This study revealed that the lower alveolar bone support level of the adjacent teeth, maxillary position of IFPs and mesial site of IFPs were significantly associated with a higher incidence of PCL.

A randomized controlled trial of various MTA materials for partial pulpotomy in permanent teeth.

OBJECTIVES: The aim of this study was to evaluate and compare the clinical applicability of various MTA materials as partial pulpotomy materials in permanent teeth. METHODS: Partial pulpotomy was performed on 104 permanent teeth from 82 people (mean 29.3±14.8years old), who met the inclusion criteria in randomized clinical trial. The teeth were divided into three groups: ProRoot MTA (n=33), OrthoMTA (n=36), RetroMTA (n=35). Clinical examination and radiographic comparison were carried out at 1, 3, 6 and 12 months after the treatment. Survival analysis was performed using the Kaplan-Meier survival curves and log rank tests. RESULTS: Partial pulpotomy sustained a high success rate up to 1year with no significant differences in the outcomes treated with three MTA materials: ProRoot MTA, 96.0%; OrthoMTA, 92.8%; RetroMTA, 96.0%. The Kaplan-Meier survival function curves showed no significant differences among three groups concerning clinical and radiographic cumulative survival rates. In addition, no potential prognostic factors related to the success rate of partial pulpotomy among age, sex, tooth type, root apex status, the site and type of pulp exposure, and the type of restoration were observed in log rank analysis. CONCLUSIONS: Partial pulpotomy with ProRoot MTA, OrthoMTA and RetroMTA had favorable results and clinical and radiographic results were not significantly different in three groups after 1year.

Computer-controlled local anesthetic delivery for painless anesthesia: a literature review.

Local anesthesia is administered to reduce pain during dental treatments, but may itself cause pain and contribute to increased dental fear. Computer-controlled local anesthetic delivery (CCLAD) is one the method to reduce patient pain during local anesthesia; it is a device that slowly administers anesthetics by using a computerized device to control the injection speed. This literature review aims to provide an objective assessment of the usefulness of CCLAD for controlling pain by reviewing papers published to date that have used CCLAD.

Management of hyperthyroid patients in dental emergencies: a case report.

The prevalence of thyroid disease, particularly hyperthyroidism, has rapidly increased in Korea in the past 10 years. Therefore, it is important to consider the complete medical history including thyroid disease in patients under dental treatment. Both the drugs used for dental treatment and psychological symptoms associated with treatment can induce emergencies in hyperthyroid patients. This case report considers emergency situations during dental treatment for hyperthyroid patients, and discusses risk factors and related concerns.

Effect of dentin treatment on proliferation and differentiation of human dental pulp stem cells.

OBJECTIVES: Sodium hypochlorite (NaOCl) is an excellent bactericidal agent, but it is detrimental to stem cell survival, whereas intracanal medicaments such as calcium hydroxide (Ca[OH]2) promote the survival and proliferation of stem cells. This study evaluated the effect of sequential NaOCl and Ca[OH]2 application on the attachment and differentiation of dental pulp stem cells (DPSCs). MATERIALS AND METHODS: DPSCs were obtained from human third molars. All dentin specimens were treated with 5.25% NaOCl for 30 min. DPSCs were seeded on the dentin specimens and processed with additional 1 mg/mL Ca[OH]2, 17% ethylenediaminetetraacetic acid (EDTA) treatment, file instrumentation, or a combination of these methods. After 7 day of culture, we examined DPSC morphology using scanning electron microscopy and determined the cell survival rate with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. We measured cell adhesion gene expression levels after 4 day of culture and odontogenic differentiation gene expression levels after 4 wk using quantitative real-time polymerase chain reaction. RESULTS: DPSCs did not attach to the dentin in the NaOCl-treated group. The gene expression levels of fibronectin-1 and secreted phosphoprotein-1 gene in both the Ca[OH]2- and the EDTA-treated groups were significantly higher than those in the other groups. All Ca[OH]2-treated groups showed higher expression levels of dentin matrix protein-1 than that of the control. The dentin sialophosphoprotein level was significantly higher in the groups treated with both Ca[OH]2 and EDTA. CONCLUSIONS: The application of Ca[OH]2 and additional treatment such as EDTA or instrumentation promoted the attachment and differentiation of DPSCs after NaOCl treatment.

Protective dental splint for oroendotracheal intubation: experience of 202 cases.

BACKGROUND: Dental injury as a result of oroendotracheal intubation during general anesthesia is very common. We report our experiences of using mouthguard to prevent dental injury during intubation based on our protocol. METHODS: This retrospective study enrolled patients referred for preanesthetic evaluation, those patients with a history of any of the dental treatments to their anterior teeth listed on our fabrication protocol from January 1, 2009 to June 30, 2010. RESULTS: No cases of dental trauma during oroendotracheal intubation were reported among the 202 patients who used a protective device. 66% of the patients had risk factors for hard tissue damage aged 10-40 years. At the ages of 40-70 years, the incidence of risk group for periodontal damage was higher. CONCLUSIONS: Preanesthetic consultation was effective for preventing dental injury, so preanesthetic questionnaire and proper dental consultation would be helpful.

Radiographic assessment of clinical root-crown ratios of permanent teeth in a healthy Korean population.

PURPOSE: The aim of this study was to determine the absolute value of the root/crown ratio (R/C ratio) using panoramic radiographs (PRGs) in a healthy Korean population. MATERIALS AND METHODS: In total, 99 patient radiographs (of 50 males and 49 females subjects; aged 16 to 24 years old) were examined, and 2,770 teeth were analyzed. Crown lengths and root lengths were measured with modified Lind's measurements using PACS tools by two examiners in two separate sessions two months apart. All data were analyzed using SPSS. The independent t-test was used to assess for gender differences, and the paired t-test was used to compare both arches with a significance level of P<.05. RESULTS: The mean R/C ratios varied from 1.29 to 1.89 (male: 1.28-1.84; females: 1.31-1.94). The highest R/C ratios were recorded for the mandibular canines (1.89), followed by the maxillary canines (1.79). The lowest R/C ratios were recorded for the maxillary second molars (1.31). In comparison with the maxillary teeth (1.29-1.78), the mandibular teeth yielded the higher R/C ratio (1.47-1.89), and this difference was significant in the females (P<.05). The difference between the genders was not statistically significant, except for the maxillary central incisors, mandibular canines and mandibular first premolars. CONCLUSION: These data may enhance the understanding of the clinical R/C ratio as a useful guideline for determining the status of teeth and the ethnic difference.

Effect of EDTA on attachment and differentiation of dental pulp stem cells.

INTRODUCTION: In regenerative endodontics, it is believed that EDTA induces odontoblast differentiation by releasing growth factors from the dentin matrix. The aim of this study was to evaluate the effect of EDTA on the attachment and differentiation of dental pulp stem cells (DPSCs). We also investigated whether the behavioral changes of DPSCs could be caused by biochemical components released from EDTA-treated dentin. METHODS: Cells were obtained from human third molars, and the stem-like nature of the cells was investigated by flow cytometric analysis. DPSCs were seeded on EDTA-treated and untreated dentin slices. After 3 days of culture, cell attachment was evaluated by cell density, fibronectin 1 gene expression level using quantitative real-time polymerase chain reaction, and scanning electron microscopy. After 21 days of culture, the expression of differentiation genes was investigated by quantitative real-time polymerase chain reaction, and calcification was observed using alizarin red S staining. To investigate the EDTA-induced growth factor release, DPSCs were cultured with or without direct contact with the EDTA-treated dentin surface. RESULTS: After 3 days of culture, both the cell density and fibronectin expression level were significantly higher in the EDTA-treated dentin group. After 3 weeks, the DPSCs on the EDTA-treated dentin surfaces showed higher expression levels of dentin sialophosphoprotein and dentin matrix protein 1, whereas the DPSCs cultured without direct contact with the EDTA-treated dentin surfaces did not exhibit these findings. CONCLUSIONS: Our results showed that EDTA induced cell attachment and odontoblastic/osteoblastic differentiation, which was observed only in the group in which the DPSCs were placed in direct contact with the EDTA-treated dentin surfaces. These findings suggest that EDTA is beneficial for achieving successful outcomes in regenerative endodontics.

Endodontic and surgical treatment of root damage caused by orthodontic miniscrew placement.

INTRODUCTION: Miniscrews are being increasingly used for anchorage control in orthodontics. Despite the concern over root damage caused by miniscrews, there are few reports of precise clinical evaluations and appropriate management of that damage. In the case presented herein, the root damage caused by the placement of miniscrews was repaired by root canal treatment and surgical intervention. METHODS: A 44-year-old man received orthodontic treatment for intrusion of the left maxillary first molar with a miniscrew anchorage system. During that treatment, the miniscrews had fallen out and had to be reinserted more than 6 times in the same area. Two years later, the patient complained of a spontaneous pain in the maxillary left molar region. Although the patient received root canal treatment, intraoral sinus tracts could still be detected, and the patient's discomfort persisted. Periradicular surgery revealed that the persistent infection was related to root surface damage caused by orthodontic miniscrew placement. Healing was achieved by a combination of root canal treatment and surgical intervention. RESULTS: Scanning electron microscopy of the damaged distobuccal root apex revealed a mature biofilm consisting of a network of matrix that contained mostly rod-like and spherical bacteria. At a 12-month recall checkup, the patient was free of pain. A repeat periapical radiograph revealed reduction of the pretreatment radiolucent lesion. CONCLUSIONS: More careful planning of miniscrew placement is necessary to lessen the danger of root damage. Furthermore, a precise evaluation of both root and pulpal damage and careful consideration of the choice of optimal treatment modality are needed.

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.