Morning headache caused by obstructive sleep apnea misdiagnosed as temporomandibular disorders-related headache: A case report.

PATIENT: A 67-year-old woman presented to our clinic with chief complaints of headache and mandibular heaviness. Physical examination revealed bilateral tenderness in the temporalis and masseter muscles, corresponding to the patient's chief complaint. Thus, a diagnosis of temporomandibular disorders (TMDs)-related headache was made. However, sleep disorders were identified after further consultation. Hence, sleep apnea-related headache was suspected due to a snoring habit with a Mallampati classification of Class IV. Out-of-center sleep testing (OCST) revealed a respiratory event index (REI) of 10.1/h and a low peripheral oxygen saturation (SpO2) of 76%. Consequently, a diagnosis of obstructive sleep apnea (OSA) was made, and treatment using the mandibular advancement device (MAD) was recommended. Following MAD treatment, the patient's sleep quality improved, and morning headaches ceased. Subsequent OCST performed while wearing the MAD showed a significant reduction in the REI to 1.6/h and an increase in the SpO2 to 86%, indicating the therapeutic efficacy of the MAD in treating OSA. DISCUSSION: MAD treatment effectively alleviated the patient's morning headaches, suggesting that sleep bruxism should not be considered the only cause of headaches. OSA should also be considered and addressed when investigating the potential causes of morning headaches in patients. CONCLUSIONS: In patients experiencing TMDs symptoms and morning headaches, TMDs should not be presumed as the sole cause. Dentists should discuss the likelihood of sleep disorders during consultations. If sleep disorders are suspected, the possibility of OSA should be considered, and sleep tests should be conducted when necessary.

Marginal fit and retention force of zirconia resin-bonded fixed dental prostheses in the posterior region with different designs.

Background/purpose: Retainer debonding of resin-bonded fixed dental prostheses (RBFDPs) is one of the major reasons for their lower survival rates than fixed dental prostheses (FDPs) with full-coverage crowns. Recent advances in milling technology have enabled the fabrication of RBFDPs with complex retainers (D-shaped designs). This study aimed to assess the marginal fit and retention force of zirconia RBFDPs with inlay-, L-, and D-shaped designs to clarify their clinical applications. Materials and methods: Three abutment teeth models without maxillary second premolars were created using inlay-, L-, and D-shaped retainer designs. The zirconia RBFDPs were designed and fabricated according to the manufacturer's instructions (n = 10). The marginal gap was measured using the silicone replica technique. Zirconia frameworks were bonded to the abutment teeth using resin cement. Tensile test was conducted after thermal cycling and dynamic loading tests. The loads during debonding or fracture were recorded. The failure pattern was analyzed by observing the fracture surface using a scanning electron microscope. Results: D-shaped RBFDPs showed a significantly larger marginal gap than inlay- and L-shaped RBFDPs (P < 0.05). However, the mean marginal values were clinically acceptable (<120 µm). The D-shaped model exhibited the highest tensile strength in the tensile tests. The inlay-shaped and most of the D-shaped RBFDPs experienced debonding with cohesive failure, whereas the L-shaped RBFDPs showed fractures near the connector. Conclusion: The D-shaped retainer design was superior to the inlay- and L-shaped designs with respect to the inhibition of retainer debonding. However, the marginal fitness needs to be improved.

Effects of immersion in 4-methacryloyloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane resin-activated liquid on microtensile bond strength of root canal dentin.

Background/purpose: 4-methacryloyloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane (4-META/MMA-TBB) resin is used for indirect restorations. We aimed to evaluate effects of immersion in 4-META/MMA-TBB-activated liquid on the bond strength of root canal dentin. Materials and methods: We used freshly extracted single-rooted human teeth. After decoronation, each root was vertically sectioned into halves; their dentin walls were polished and flattened. The control group underwent dentin treatment with Green Activator. The immersion group was treated with Green Activator and Teeth Primer and immersed in 4-META/MMA-TBB-activated liquid. After bonding the resin blocks with Super-Bond, microtensile bond strength (µTBS) tests were performed (n = 6), and fracture surfaces were analyzed. Before surface treatment, dentin was immersed in a sodium fluorescein solution for 3 h, and resin blocks were bonded with Super-Bond with rhodamine B as in the bond strength test. The bonded cross section was observed using confocal laser scanning microscopy (CLSM). Results: µTBS was significantly higher in the immersion group than in the control group (61.5 [51.3-66.7] vs. 33.0 [20.4-57.8] MPa; P < 0.05). Fracture mode analysis showed that, compared with the control group, the immersion group had a significantly lower rate of adhesive failure at the dentin interface and a significantly higher rate of cohesive failure in Super-Bond (P < 0.01). CLSM showed a water droplet-like accumulation of fluorescein dye above the hybrid layer in the control group, not in the immersion group. Conclusion: Immersion in a 4-META/MMA-TBB-activated liquid inhibited water exudation from the root canal dentin and improved the bond strength.

Surface strain at the cervical area and fracture strength of flared root canals reinforced using a zirconia tube and glass-fiber post.

Background/purpose: Recently, an effective core build-up system for teeth with flared root canals is needed. This research aimed to evaluate the effect of foundation restorations using a composite resin core with a fiber post reinforced with a zirconia tube for the surface strain at the cervical area and the fracture load of teeth with flared root canals. Materials and methods: Bovine teeth were shaped to mimic human premolars with flared root canals and restored using three types of composite resin foundation restorations with each materials described below: a fiber post (FC), a zirconia tube (ZC), a fiber post and zirconia tube (ZFC). Each specimen was restored with a zirconia crown. The surface strains of the specimens at the cervical area and fracture loads were analyzed using a one-way analysis of variance (ANOVA), followed by Tukey's honest significant difference test. Results: The surface strains of Groups ZFC and ZC were significantly lower than that of Group FC in the buccal root. The fracture strengths of Groups ZFC and ZC were significantly higher than that of Group FC. The strength of Group ZFC was significantly higher than that of Group ZC. Conclusion: The use of a composite resin core with a zirconia tube for the simulated premolar with flared root canals reduced surface strain at the cervical area and provided higher fracture strength compared to using a composite resin core with a fiber post. And the zirconia tubes provided even higher fracture strength when used with a fiber post.

Do oral conditions influence the incidence of bloodstream infection after hematopoietic stem cell transplantation? A retrospective study in Japan.

PURPOSE: This study aimed to evaluate the incidence of bloodstream infection (BSI) among patients undergoing hematopoietic stem cell transplantation (HSCT) for teeth indicated for extraction. METHODS: Patients who underwent HSCT at Toranomon Hospital (Tokyo, Japan) between January 2017 and December 2019 were retrospectively evaluated. The incidence of BSI among patients with teeth indicated for extraction who did not undergo extraction (oral high-risk group) and patients who did not have this risk (oral low-risk group) was compared. RESULTS: Among the 191 consecutive patients included in this study, 119 patients were classified as undergoing high-risk transplantation. BSI after HSCT was observed in 32 out of 60 (53.3%) patients and 56 out of 131 (42.7%) patients in the oral low-risk and oral high-risk groups, respectively (p = 0.173). Multivariable analyses revealed that the presence of > 3 teeth as intraoral sources of infection and age over 50 years were determinants of BSI originating from the oral cavity after engraftment (odds ratio [OR], 9.11; 95% confidential interval [CI] 2.27-36.61]; p = 0.002; OR, 3.22; CI [1.47-7.08], p = 0.004, respectively). CONCLUSION: In patients undergoing HSCT, the presence of less than three intraoral sources of infection did not affect the incidence of BSI after HSCT.

DO ORAL CARE AND REHABILITATION IMPROVE COGNITIVE FUNCTION? A SYSTEMATIC REVIEW OF CLINICAL STUDIES.

OBJECTIVES: An increasing number of studies have identified an association between oral health status and cognitive function. However, the effect of oral interventions, including oral health care, dental treatment and oral motor exercises, on cognitive function remains unclear. This systematic review examined whether oral interventions contribute to the long-term improvement of cognitive status. METHODS: Four databases were searched (MEDLINE, Web of Science, Cochrane Library, and ICHUSHI Web) to identify randomized and nonrandomized controlled trial studies and prospective cohort studies from inception until 1 September 2023, published in English or Japanese. The Cochrane risk of bias tool for randomized controlled trials and the risk of bias assessment tool for nonrandomized studies were used to assess bias risk. RESULTS: A total of 20 articles were included in the qualitative analysis; 13 articles were published in English, and 7 were published in Japanese. The implemented interventions were oral care in 8 studies, dental treatment in 8 studies, and oral motor exercise in 4 studies. One study found a significant effect on attention following oral care intervention. Some dental treatments influenced cognitive function, although a clear positive effect was not determined. In 1 study, attention and working memory improved in the chewing exercise group. CONCLUSIONS: Several studies verified the improvement effects of oral interventions, such as oral care, dental treatment, and oral motor exercise, on cognitive function or impairment. However, there was still a lack of conclusive evidence that such an intervention clearly improved cognitive function. To clarify the effects of oral interventions on cognitive function, it is necessary to examine participants, interventions, and outcome measures in detail.

Clinical application of robots in dentistry: A scoping review.

PURPOSE: The surge in digitalization and artificial intelligence has led to the wide application of robots in various fields, but their application in dentistry started relatively late. This scoping review aimed to comprehensively explore and map the current status of the clinical application of robots in dentistry. STUDY SELECTION: An iterative approach was used to gather as much evidence as possible from four online databases, including PubMed, the China National Knowledge Infrastructure, the Japan Science and Technology Information Aggregator, Electronic, and the Institute of Electrical and Electronics Engineers, from January 1980 to December 2022. RESULTS: A total of 113 eligible articles were selected from the search results, and it was found that most of the robots were developed and applied in the United States (n = 56; 50%). Robots were clinically applied in oral and maxillofacial surgery, oral implantology, prosthodontics, orthodontics, endodontics, and oral medicine. The development of robots in oral and maxillofacial surgery and oral implantology is relatively fast and comprehensive. About 51% (n = 58) of the systems had reached clinical application, while 49% (n = 55) were at the pre-clinical stage. Most of these are hard robots (90%; n = 103), and their invention and development were mainly focused on university research groups with long research periods and diverse components. CONCLUSIONS: There are still limitations and gaps between research and application in dental robots. While robotics is threatening to replace clinical decision-making, combining it with dentistry to gain maximum benefit remains a challenge for the future.

Emergence angle: Comprehensive analysis and machine learning prediction for clinical application.

PURPOSE: To analyze and compare the emergence angle (EA) using two measurement methods, conventional and modified (EA-GPT and EA-R), the EAs of all-natural teeth were evaluated and classified to derive a suitable and predictable clinically applicable measurement method. METHODS: Natural human teeth (n=600) were classified, cleaned, and thoroughly inspected. Teeth were scanned using an intraoral scanner. The scanned data were analyzed using three-dimensional analysis software for both methods with several points per surface. A Bland-Altman analysis was used for statistical analysis and a heat map and a nonparametric density plot to assess the repetition and distribution. An XGBoost regression model was used for prediction. RESULTS: The EA-R method showed significantly different values compared to the EA-GPT method, representing an increase of 17.5-20.7% for the proximal surfaces. An insignificant difference between the two methods was observed for other surfaces. Different teeth classes showed variation in the normal range, thereby resulting in a new classification of the EA for all-natural teeth based on the interquartile range. The machine learning gradient boosting model predicted conventional data with an average mean absolute error of 0.9. CONCLUSIONS: Variations in the natural teeth EA and measurement methods, suggest a new classification for EA. The established artificial intelligence method demonstrated robust performance, which could aid in implementing EA measurement in prosthetic designs.

Knowledge acquisition efficacy of a remote flipped classroom on learning about removable partial dentures.

PURPOSE: Coronavirus disease 2019 has forced the use of remote education worldwide. In 2020, the authors conducted a fully digitized, remote flipped (RF) classroom focusing on removable partial dentures. This study aimed to evaluate the learning outcomes of the RF classroom and compare these with those of the on-site classroom. METHODS: The fourth-year dental students in 2017-2019 attended on-site flipped classroom (OF; n=70) or on-site lecture classroom (OL; n=67), and those in 2020 (n=58) attended the RF classroom. Lecture videos and text were provided online in the OF and RF groups, while only the text was given to the OL group. Individual and group tests were conducted to assess knowledge acquisition one week after all the classes ended. A one-way analysis of variance following Tukey's test was performed to compare individual/group test scores among the OF, OL, and RF groups. Multilevel linear regression analysis was performed to identify the factors associated with an increase in each test score. RESULTS: The mean individual test scores in the RF and OF groups were significantly higher than in the OL group (P<0.01). The mean group test score in the RF group was significantly higher than in the OF and OL groups (P<0.001). The multilevel analysis identified remote and flipped classroom styles in the individual test, and the remote style in the group test, as significant effective factors in learning (P<0.05). CONCLUSIONS: These results suggest that the RF classroom is more effective than the on-site lecture in knowledge acquisition in undergraduate prosthodontic education.

Quantitative text analysis of the mechanisms of tooth injury: Analysis of accidents in five sports that occurred in 15 years under school control.

BACKGROUND/AIM: Dental trauma may occur in school settings and it can impact patients' quality of life. Analysis of the occurrences of dental trauma is essential in identifying preventive methods. There are numerous reports of such accidents but most are quantitative analyses with limited data. The aim of this study was to extract information on the mechanisms of injuries that leads to prevention by performing a qualitative analysis of the occurrence of dental trauma. MATERIAL AND METHODS: After screening 7684 cases of dental injuries that occured in schools and were reported to the Japan Sports Council between 2005 and 2020, 533 detailed descriptions of injuries that occurred during sports were included. Quantitative text analysis was performed on the target data by performing statistical analysis, extracting frequently used words, and creating a co-occurrence network. Injury mechanisms were evaluated based on appearance of words. RESULTS: Dental injuries occurred frequently in five sports included in the survey. They were in order of decreasing frequency: baseball, basketball, soccer, volleyball, and rugby. Males were injured more often in all sports other than volleyball. The number of accidents increased in all sports among high school students. The frequent word list and co-occurrence network were different for each sport. This allowed typical accident occurrence mechanisms to be extracted for these five sports. CONCLUSIONS: Typical accident occurrence mechanisms were extracted from quantitative text analysis targeting free texts on the occurrence of accidents for five sports. Quantitative text analysis is useful for the evaluation of accident cases, which may aid in accident prevention.

Fracture strength of flared root canals reinforced using different post and core materials.

PURPOSE: To examine the fracture strength and fracture mode of flared root canals reinforced with different post and core materials. MATERIALS AND METHODS: Forty endodontically treated bovine teeth structured to mimic human mandibular premolars with flared root canals were reinforced with resin composite and glass fiber post (FRC), composite resin (RC), ceramic core (LD), and ceramic core with resin composite reinforcement (RLD), and restored with single zirconia crowns (n = 10 in each group). The fracture strength and mode of the root canals restored with zirconia crown were assessed. The fracture strength was compared with a one-way analysis of variance (ANOVA) following Tukey HSD tests. A multiple regression analysis was conducted to test the effect of the post/core materials on the fracture loads. Fisher's exact test was used in the failure mode analysis. RESULTS: The mean fracture strength of RLD was significantly higher than RC, FRC, and LD (p < 0.05), while no significant differences were found among RC, FRC, and LD (p < 0.05). The regression analysis found that the fracture strength using the lithium disilicate was significantly lower for the post and higher for the core than that using the resin composite (p < 0.05), and there were no significant difference in the fracture strengths between the resin composite and glass fiber used for the post (p > 0.05). Most of the specimens exhibited root fractures, and no significant differences were observed among the groups (p < 0.05). CONCLUSIONS: The results of this study suggest that reinforcement of flared root canals using a combination of resin composite for the core and lithium disilicate ceramic for the post is superior to resin composite and glass fiber in mechanical properties when restoring a single crown.

A composite resin core with a new zirconia tube reduces the surface strain at the cervical area of a mandibular molar: A model tooth study.

PURPOSE: This study aimed to evaluate the surface strain at the cervical area of endodontically treated molars with a large pulp chamber restored using a composite resin core with three different types of core build-up systems. METHODS: Reproduction models of human mandibular molars with prepared post spaces were used in this study. Roots duplicated with a composite resin were used as the experimental teeth. Three types of core build-up systems were used: composite resin core(RC), composite resin core with fiber posts (FC), and composite resin core with a prefabricated zirconia tube (ZC). Each group comprised eight specimens. Crowns made of yttria partially stabilized zirconia were cemented with dual-cure resin cement. Four strain gauges were attached to the surfaces of each specimen: the cervical area of the root and crown, on the buccal and lingual sides. The surface strain at each cervical area was measured using a static loading test and statistically analyzed. RESULTS: In the case of static loading to the buccal cusp inner slope, ZC showed a significantly lower strain than RC in the crown on the buccal side and in the root and FC in the root. In the central fossa, ZC showed a significantly lower strain than FC in the root on the lingual side. CONCLUSIONS: The prefabricated zirconia tube reduced the surface strain at the cervical area of the buccal/lingual root in molars; however, the effect was small in the cervical area of the crown.

Texture-Based Neural Network Model for Biometric Dental Applications.

BACKGROUND: The aim is to classify dentition using a novel texture-based automated convolutional neural network (CNN) for forensic and prosthetic applications. METHODS: Natural human teeth (n = 600) were classified, cleaned, and inspected for exclusion criteria. The teeth were scanned with an intraoral scanner and identified using a texture-based CNN in three steps. First, through preprocessing, teeth images were segmented by extracting the front-facing region of the teeth. Then, texture features were extracted from the segmented teeth images using the discrete wavelet transform (DWT) method. Finally, deep learning-based enhanced CNN models were used to identify these images. Several experiments were conducted using five different CNN models with various batch sizes and epochs, with and without augmented data. RESULTS: Based on experiments with five different CNN models, the highest accuracy achieved was 0.8 and the precision was 0.8 with a loss value of 0.9, a batch size of 32, and 250 epochs. A comparison of deep learning models with different parameters showed varied accuracy between the different classes of teeth. CONCLUSION: The accuracy of the point-based CNN method was promising. This texture-identification method will pave the way for many forensic and prosthodontic applications and will potentially help improve the precision of dental biometrics.

Effects of Jaw-Opening Exercises with/without Pain for Temporomandibular Disorders: A Pilot Randomized Controlled Trial.

This study aimed to evaluate the effects of jaw-opening exercises with and without pain on temporomandibular disorders (TMDs), specifically in relation to pain intensity and range-of-mouth opening in patients with TMDs. Participants were randomly assigned to either the jaw-opening exercise with pain (JE w/pain) or the jaw-opening exercise without pain (JE w/o pain) groups, and each exercise was performed for eight weeks. TMDs pain intensity was assessed using a 100-mm visual analog scale (VAS), and the range-of-mouth opening was evaluated at the baseline (T0), 2 weeks (T1), 4 weeks (T2), and 8 weeks (T3). Of the 61 participants, 57 (JE w/pain group, n = 30; JE w/o pain group, n = 27) were included in the analysis. The range-of-mouth opening and TMDs pain intensity improved from T1 to T3 in both groups. The JE w/pain group showed significant differences at T3 compared to T1 (pain-free unassisted mouth opening, p = 0.006; jaw-opening pain, p = 0.014; chewing pain, p = 0.018). In addition, the JE w/pain group showed significantly greater changes in the maximum unassisted mouth opening at T2 and T3 than the JE w/o pain group (T2, p < 0.001; T3, p = 0.003). Thus, jaw-opening exercises, until the occurrence of pain, may be effective in patients with TMDs.

Anti-Inflammatory Therapy for Temporomandibular Joint Osteoarthritis Using mRNA Medicine Encoding Interleukin-1 Receptor Antagonist.

Messenger RNA (mRNA) is an emerging drug modality for protein replacement therapy. As mRNA efficiently provides protein expression in post-mitotic cells without the risk of insertional mutagenesis, direct delivery of mRNA can be applied, not only as an alternative to gene therapy, but also for various common diseases such as osteoarthritis (OA). In this study, using an mRNA-encoding interleukin-1 receptor antagonist (IL-1Ra), we attempted anti-inflammatory therapy in a rat model of the temporomandibular joint (TMJ) OA, which causes long-lasting joint pain with chronic inflammation. For the intra-articular injection of mRNA, a polyplex nanomicelle, our original polymer-based carrier, was used to offer the advantage of excellent tissue penetration with few immunogenic responses. While the protein expression was transient, a single administration of IL-1Ra mRNA provided sustained pain relief and an inhibitory effect on OA progression for 4 weeks. The mRNA-loaded nanomicelles provided the encoded protein diffusely in the disc and articular cartilage without upregulation of the expression levels of the pro-inflammatory cytokines IL-6 and tumor necrosis factor-α (TNF-α). This proof-of-concept study demonstrates how anti-inflammatory proteins delivered by mRNA delivery using a polyplex nanomicelle could act to alleviate OA, stimulating the development of mRNA therapeutics.

A systematic review of digital removable partial dentures. Part I: Clinical evidence, digital impression, and maxillomandibular relationship record.

PURPOSE: This study comprehensively reviewed the current status of digital workflows in fabricating removable partial dentures (RPDs) using evidence from clinical trials and case reports. STUDY SELECTION: We performed a systematic review of the literature on the materials and fabrication of RPDs using digital technologies published in online databases from 1980 to 2020. We selected eligible articles from the search results, retrieved information on digital RPDs from these, and conducted a qualitative analysis. We report evidence from clinical papers and case reports, digital impression-taking methods, and maxillomandibular relationship (MMR) records. RESULTS: A case report electronically published in 2019 introduced a clasp-retained RPD fabricated via a full-digital workflow without a gypsum definitive cast. Computer-aided design and computer-aided manufacturing of double-crown-retained RPDs with nonmetal materials were described in some case reports. Intraoral scanners were used to obtain digital impressions and MMR records in the fabrication of digital RPDs, which have potential advantages for reducing the number of clinical appointments and simplifying laboratory procedures. Evidence from clinical trials is scarce; a randomized controlled trial reported higher patient satisfaction with digital clasp-retained RPDs than with conventional RPDs. CONCLUSIONS: Full-digital RPDs can be fabricated without a gypsum definitive cast. However, the indication for full-digital RPDs is limited to cases with Kennedy Class III/IV partially edentulous arches with several missing teeth. Challenges in digital impression-taking and MMR recording remain to be solved to extend these indications. More evidence from clinical trials is required to evaluate the efficacy and usefulness of digital RPDs.

A systematic review of digital removable partial dentures. Part II: CAD/CAM framework, artificial teeth, and denture base.

PURPOSE: This study comprehensively reviewed the current status of the digital workflow of removable partial dentures (RPDs) and summarized information about the fabrication methods and material properties of the dental framework, artificial teeth, and denture base. STUDY SELECTION: We performed a systematic review of the literature published in online databases from January 1980 to April 2020 regarding RPD fabrication and materials used in the related digital technology. We selected eligible articles, retrieved information regarding digital RPDs, and conducted qualitative/quantitative analyses. In this paper, the computer-aided design/computer-aided manufacturing (CAD/CAM) framework, artificial teeth, and denture base materials are reported. RESULTS: A variety of materials, such as cobalt-chromium alloy, titanium, zirconia, and polyether ether ketone, are used for dental CAD/CAM frameworks. The mechanical strength of the metal materials used for the CAD/CAM framework was superior to that of the cast framework. However, the fitness and surface roughness of the framework and clasp fabricated using a selective laser melting (SLM) method were not superior to those obtained via cast fabrication. Most material properties and the surface roughness of poly methyl methacrylate (PMMA) discs used for digital RPDs were superior to those of heat-cured PMMA. CONCLUSION: The use of a CAD/CAM framework and PMMA disc for digital RPDs offers numerous advantages over conventional RPDs. However, technical challenges regarding the accuracy and durability of adhesion between the framework and denture base remain to be solved. In digital fabrication, human technical factors influence the quality of the framework.

Short-term effect of thermoplastic resin removable partial dentures on periodontal health: A randomized cross-over trial.

PURPOSE: This study aimed to compare the short-term effects of thermoplastic resin removable partial dentures (TR-RPDs), referred to as non-metal clasp dentures, with those of metal-clasp-retained RPDs (MC-RPDs) on the periodontal health of abutment teeth. METHODS: A randomized cross-over trial was conducted in 28 partially dentate patients. Participants were randomized into two groups and received MC-RPDs followed by TR-RPDs, or vice versa, for 3 months. Periodontal clinical parameters, such as the plaque index, gingival index, probing pocket depth, tooth mobility, and microbiological status of the abutment teeth, were evaluated at the delivery and 3 months after using each RPD. RESULTS: Of the 28 patients enrolled, 24 (mean age, 67.3 years) completed the trial, and 55 abutment teeth were evaluated. The periodontal condition of the abutment teeth did not deteriorate after 3 months of using both types of RPDs. There was no statistically significant difference in the plaque index, gingival index, probing pocket depth, tooth mobility, and the red complex bacteria between TR- and MC-RPDs (p >0.05). The Periotest value for TR-RPDs was significantly lower than that for MC-RPDs (p <0.05). However, this difference was not clinically significant. CONCLUSIONS: These results suggest that the influence of TR-RPDs on the periodontal health of abutment teeth was limited within 3 months of use.