Junichiro Wada - Academia.edu (original) (raw)

Papers by Junichiro Wada

Research paper thumbnail of Effect of splinting material type and location on resistance against deflection force of splinted periodontally compromised teeth with hypermobility

Journal of The Mechanical Behavior of Biomedical Materials, Jun 1, 2023

Research paper thumbnail of Radiographic predictive factors for 10-year survival of removable partial denture abutment teeth: Alveolar bone level and density

Journal of prosthodontic research, 2022

Removable partial dentures (RPDs) are widely used for prosthodontic treatment of partially edentu... more Removable partial dentures (RPDs) are widely used for prosthodontic treatment of partially edentulous patients. As RPDs are supported by remaining abutment teeth, the survival rate of abutment teeth is lower than that of non-abutment teeth in RPD wearers[1,2]. Additionally, abutment teeth for RPDs are at a higher risk of loss than those for fixed bridges[3-5]. Previously reported survival rates of RPD abutment teeth vary widely over longer follow-up periods. The 10-year survival rates have been reported to range from 56.0% to 77.5%[1,3,6]. Preoperative conditions and postoperative changes are implicated in the wide variation in long-term survival rates for RPD abutment teeth. Various predictive factors for RPD abutment teeth have been reported in previous studies. These include the crown-root ratio (CR ratio), tooth mobility, probing depth, root canal treatment, and radiological bone level at baseline[2,5,7-10]. In particular, an abutment tooth originally weakened by periodontitis is predicted to have an undesirable prognosis[5,8] because a continuous mechanical stress on RPD abutment teeth damages the periodontal supporting tissues[4,7]. In previous studies, various predictors, including radiographic factors, were evaluated only at diagnosis, that is, before prosthodontic treatment. However, even though postoperative periodontal changes are clinically important, they have never been considered in such predictive modeling. Generally, patients are followed-up according to their initial prognosis at the completion of RPD treatment. At the follow-up, postoperative periodontal changes, such as progression of tooth mobility, attachment loss, and alveolar bone resorption, are carefully assessed. Radiographic assessments are performed when needed. Although the clinicians plan postoperative therapy and/or further visits based on the results of the follow-up assessment, there is little evidence on the impact of postoperative periodontal changes on

Research paper thumbnail of Effect of splinting material type and location on resistance against deflection force of splinted periodontally compromised teeth with hypermobility

Journal of the Mechanical Behavior of Biomedical Materials

Research paper thumbnail of Effect of abutment tooth location on the accuracy of digital impressions obtained using an intraoral scanner for removable partial dentures

Journal of prosthodontic research, 2023

In partially edentulous dental arches with multiple mucosal areas, RPD abutment teeth adjacent to... more In partially edentulous dental arches with multiple mucosal areas, RPD abutment teeth adjacent to the mucosal areas are widely distributed in dentition. However, no previous report has presented a detailed evaluation of data accuracy based on individual RPD abut

Research paper thumbnail of How to avoid iatrogenic lingual nerve injury in the retromolar area: an anatomical study of retromolar pad and lingual nerve

Surgical and Radiologic Anatomy, 2020

Purpose This study aimed to investigate the relationship between the retromolar gland and pad, an... more Purpose This study aimed to investigate the relationship between the retromolar gland and pad, and the relationship between the LN and retromolar gland/pad to establish a new landmark for avoiding LN injury. Methods Sixty-two lingual nerves from fresh-frozen cadavers were used for this study. The age of the specimens at the time of death ranged from 57 to 98 with a mean of 76.5 years. The mucous incision was made into the medial border of the retromolar pad and the submucosal tissue depth of the initial incision was bluntly dissected to expose the lingual nerve. When the LN was identified, the mucosa overlying the retromolar pad was removed to expose the retromolar gland to confirm if the retromolar pad corresponds to the retromolar gland. Results On all sides, the lingual nerve was found to course medial to the retromolar pad and inferior to the inferior border of the superior pharyngeal constrictor muscle to enter the sublingual space via the pterygomandibular space. The retromolar pad corresponded to the retromolar gland on all sides. This demonstrated that the retromolar pad is an overlying mucosa of the retromolar gland. No LN was found to travel through the retromolar gland. Conclusion We suggest that the retromolar pad can be used as a new landmark for avoiding iatrogenic LN injury.

Research paper thumbnail of A case rehabilitated with fixed bridge and clasp-retained removable partial dentures for a partially edentulous patient with cosmetic disturbance and severe periodontal disease

Annals of Japan Prosthodontic Society, 2015

Patient: A 62-year-old female patient presented with chewing difficulty and a request for good es... more Patient: A 62-year-old female patient presented with chewing difficulty and a request for good esthetics. The occlusal function was severely compromised because of increased mobility of the posterior dentition. Following the extraction of hopeless teeth, partially edentulous arches were restored with a maxillary nine-unit fixed restoration and maxillary and mandibular bilateral free-end saddle dentures. Discussion: The oral health-related quality of life and subjective chewing ability were improved and high patient satisfaction was reported after the definitive prosthodontic replacements. The results were partly due to the effects of reconstructed occlusion by the fixed splinting and removable partial dentures that were rigidly retained in the maxillary and mandibular arches by the Co-Cr precision frameworks. The periodontal tissues and restorations have been maintained for more than 3 years. Conclusion: Periodic post-operative recalls suggest that a combination of a long-span fixed bridge and removable partial dentures functions well for the partially edentulous patient with advanced periodontitis.

Research paper thumbnail of Influence of the Covering Area of Major Connectors of Mandibular Dentures on the Accuracy of Speech Production: A Pilot Study

Folia Phoniatrica et Logopaedica, 2019

Background/Objectives: Speech impairment during the initial phase of removable partial denture (R... more Background/Objectives: Speech impairment during the initial phase of removable partial denture (RPD) treatment can prevent patient adaptation to RPDs. This quasi-experimental study aimed to investigate the influence of the covering area of major connectors located in the mandibular anterior region on the accuracy of speech production. Methods: Fifteen adults (12 men and 3 women aged 26–40 years) with healthy dentition were recruited. Four target syllables were used for the assessments: [ʃi], [ʧi], [çi], and [ki]. There were four speaking conditions: without a connector (control), wearing lingual bar (5 mm width), wearing lingual plates (12 mm width), and wearing connectors covering the occlusal surface of lower dentition (16 mm width; CO). The accuracy of speech production was evaluated by mean appearance ratio of correct labels (MARC) and incorrect labels (MARIC) of the phonetic segments which were calculated with a speech evaluation system (VoiceAnalyzer). Results: The MARC in the...

Research paper thumbnail of Influence of the width and cross-sectional shape of major connectors of maxillary dentures on the accuracy of speech production

Folia phoniatrica et logopaedica : official organ of the International Association of Logopedics and Phoniatrics (IALP), 2014

To investigate the effects of the width and cross-sectional shape of the major connectors of maxi... more To investigate the effects of the width and cross-sectional shape of the major connectors of maxillary dentures located in the middle area of the palate on the accuracy of phonetic output of consonants using an originally developed speech recognition system. Nine adults (4 males and 5 females, aged 24-26 years) with sound dentition were recruited. The following six sounds were considered: [∫i], [t∫i], [ɾi], [ni], [çi], and [ki]. The experimental connectors were fabricated to simulate bars (narrow, 8-mm width) and plates (wide, 20-mm width). Two types of cross-sectional shapes in the sagittal plane were specified: flat and plump edge. The appearance ratio of phonetic segment labels was calculated with the speech recognition system to indicate the accuracy of phonetic output. Statistical analysis was conducted using one-way ANOVA and Tukey's test. The mean appearance ratio of correct labels (MARC) significantly decreased for [ni] with the plump edge (narrow connector) and for [ki]...

Research paper thumbnail of Chronological grey scale changes in supporting alveolar bone by removable partial denture placement on patients with periodontal disease: A 6-month follow-up study using digital subtraction analysis

Journal of dentistry, Jan 3, 2017

The purpose was to assess the early effects of removable partial denture (RPD) placement on abutm... more The purpose was to assess the early effects of removable partial denture (RPD) placement on abutment teeth in patients with periodontal disease. Fifteen distal-extension RPDs and 19 abutment teeth were evaluated in 13 patients with moderate-to-severe periodontal diseases. Clinical periodontal records and grey level (GL) score based on digital subtraction radiography were measured on the day of denture placement (baseline) and at 1day, 1 week, 1 month, 3 months, and 6 months after the placement. Occlusal force on total dentition (Ft) and abutment tooth (Fa) were recorded with (baseline) and without denture on the day of the placement, and with denture in the follow-up examinations. No statistically significant difference between a follow-up period and the baseline was found in the clinical periodontal and occlusal force records, except for Ft with denture on the day of the placement, which was significantly lower than the baseline (p<0.05). The GL at distal crestal of the abutment...

Research paper thumbnail of Effect of splinting material type and location on resistance against deflection force of splinted periodontally compromised teeth with hypermobility

Journal of The Mechanical Behavior of Biomedical Materials, Jun 1, 2023

Research paper thumbnail of Radiographic predictive factors for 10-year survival of removable partial denture abutment teeth: Alveolar bone level and density

Journal of prosthodontic research, 2022

Removable partial dentures (RPDs) are widely used for prosthodontic treatment of partially edentu... more Removable partial dentures (RPDs) are widely used for prosthodontic treatment of partially edentulous patients. As RPDs are supported by remaining abutment teeth, the survival rate of abutment teeth is lower than that of non-abutment teeth in RPD wearers[1,2]. Additionally, abutment teeth for RPDs are at a higher risk of loss than those for fixed bridges[3-5]. Previously reported survival rates of RPD abutment teeth vary widely over longer follow-up periods. The 10-year survival rates have been reported to range from 56.0% to 77.5%[1,3,6]. Preoperative conditions and postoperative changes are implicated in the wide variation in long-term survival rates for RPD abutment teeth. Various predictive factors for RPD abutment teeth have been reported in previous studies. These include the crown-root ratio (CR ratio), tooth mobility, probing depth, root canal treatment, and radiological bone level at baseline[2,5,7-10]. In particular, an abutment tooth originally weakened by periodontitis is predicted to have an undesirable prognosis[5,8] because a continuous mechanical stress on RPD abutment teeth damages the periodontal supporting tissues[4,7]. In previous studies, various predictors, including radiographic factors, were evaluated only at diagnosis, that is, before prosthodontic treatment. However, even though postoperative periodontal changes are clinically important, they have never been considered in such predictive modeling. Generally, patients are followed-up according to their initial prognosis at the completion of RPD treatment. At the follow-up, postoperative periodontal changes, such as progression of tooth mobility, attachment loss, and alveolar bone resorption, are carefully assessed. Radiographic assessments are performed when needed. Although the clinicians plan postoperative therapy and/or further visits based on the results of the follow-up assessment, there is little evidence on the impact of postoperative periodontal changes on

Research paper thumbnail of Effect of splinting material type and location on resistance against deflection force of splinted periodontally compromised teeth with hypermobility

Journal of the Mechanical Behavior of Biomedical Materials

Research paper thumbnail of Effect of abutment tooth location on the accuracy of digital impressions obtained using an intraoral scanner for removable partial dentures

Journal of prosthodontic research, 2023

In partially edentulous dental arches with multiple mucosal areas, RPD abutment teeth adjacent to... more In partially edentulous dental arches with multiple mucosal areas, RPD abutment teeth adjacent to the mucosal areas are widely distributed in dentition. However, no previous report has presented a detailed evaluation of data accuracy based on individual RPD abut

Research paper thumbnail of How to avoid iatrogenic lingual nerve injury in the retromolar area: an anatomical study of retromolar pad and lingual nerve

Surgical and Radiologic Anatomy, 2020

Purpose This study aimed to investigate the relationship between the retromolar gland and pad, an... more Purpose This study aimed to investigate the relationship between the retromolar gland and pad, and the relationship between the LN and retromolar gland/pad to establish a new landmark for avoiding LN injury. Methods Sixty-two lingual nerves from fresh-frozen cadavers were used for this study. The age of the specimens at the time of death ranged from 57 to 98 with a mean of 76.5 years. The mucous incision was made into the medial border of the retromolar pad and the submucosal tissue depth of the initial incision was bluntly dissected to expose the lingual nerve. When the LN was identified, the mucosa overlying the retromolar pad was removed to expose the retromolar gland to confirm if the retromolar pad corresponds to the retromolar gland. Results On all sides, the lingual nerve was found to course medial to the retromolar pad and inferior to the inferior border of the superior pharyngeal constrictor muscle to enter the sublingual space via the pterygomandibular space. The retromolar pad corresponded to the retromolar gland on all sides. This demonstrated that the retromolar pad is an overlying mucosa of the retromolar gland. No LN was found to travel through the retromolar gland. Conclusion We suggest that the retromolar pad can be used as a new landmark for avoiding iatrogenic LN injury.

Research paper thumbnail of A case rehabilitated with fixed bridge and clasp-retained removable partial dentures for a partially edentulous patient with cosmetic disturbance and severe periodontal disease

Annals of Japan Prosthodontic Society, 2015

Patient: A 62-year-old female patient presented with chewing difficulty and a request for good es... more Patient: A 62-year-old female patient presented with chewing difficulty and a request for good esthetics. The occlusal function was severely compromised because of increased mobility of the posterior dentition. Following the extraction of hopeless teeth, partially edentulous arches were restored with a maxillary nine-unit fixed restoration and maxillary and mandibular bilateral free-end saddle dentures. Discussion: The oral health-related quality of life and subjective chewing ability were improved and high patient satisfaction was reported after the definitive prosthodontic replacements. The results were partly due to the effects of reconstructed occlusion by the fixed splinting and removable partial dentures that were rigidly retained in the maxillary and mandibular arches by the Co-Cr precision frameworks. The periodontal tissues and restorations have been maintained for more than 3 years. Conclusion: Periodic post-operative recalls suggest that a combination of a long-span fixed bridge and removable partial dentures functions well for the partially edentulous patient with advanced periodontitis.

Research paper thumbnail of Influence of the Covering Area of Major Connectors of Mandibular Dentures on the Accuracy of Speech Production: A Pilot Study

Folia Phoniatrica et Logopaedica, 2019

Background/Objectives: Speech impairment during the initial phase of removable partial denture (R... more Background/Objectives: Speech impairment during the initial phase of removable partial denture (RPD) treatment can prevent patient adaptation to RPDs. This quasi-experimental study aimed to investigate the influence of the covering area of major connectors located in the mandibular anterior region on the accuracy of speech production. Methods: Fifteen adults (12 men and 3 women aged 26–40 years) with healthy dentition were recruited. Four target syllables were used for the assessments: [ʃi], [ʧi], [çi], and [ki]. There were four speaking conditions: without a connector (control), wearing lingual bar (5 mm width), wearing lingual plates (12 mm width), and wearing connectors covering the occlusal surface of lower dentition (16 mm width; CO). The accuracy of speech production was evaluated by mean appearance ratio of correct labels (MARC) and incorrect labels (MARIC) of the phonetic segments which were calculated with a speech evaluation system (VoiceAnalyzer). Results: The MARC in the...

Research paper thumbnail of Influence of the width and cross-sectional shape of major connectors of maxillary dentures on the accuracy of speech production

Folia phoniatrica et logopaedica : official organ of the International Association of Logopedics and Phoniatrics (IALP), 2014

To investigate the effects of the width and cross-sectional shape of the major connectors of maxi... more To investigate the effects of the width and cross-sectional shape of the major connectors of maxillary dentures located in the middle area of the palate on the accuracy of phonetic output of consonants using an originally developed speech recognition system. Nine adults (4 males and 5 females, aged 24-26 years) with sound dentition were recruited. The following six sounds were considered: [∫i], [t∫i], [ɾi], [ni], [çi], and [ki]. The experimental connectors were fabricated to simulate bars (narrow, 8-mm width) and plates (wide, 20-mm width). Two types of cross-sectional shapes in the sagittal plane were specified: flat and plump edge. The appearance ratio of phonetic segment labels was calculated with the speech recognition system to indicate the accuracy of phonetic output. Statistical analysis was conducted using one-way ANOVA and Tukey's test. The mean appearance ratio of correct labels (MARC) significantly decreased for [ni] with the plump edge (narrow connector) and for [ki]...

Research paper thumbnail of Chronological grey scale changes in supporting alveolar bone by removable partial denture placement on patients with periodontal disease: A 6-month follow-up study using digital subtraction analysis

Journal of dentistry, Jan 3, 2017

The purpose was to assess the early effects of removable partial denture (RPD) placement on abutm... more The purpose was to assess the early effects of removable partial denture (RPD) placement on abutment teeth in patients with periodontal disease. Fifteen distal-extension RPDs and 19 abutment teeth were evaluated in 13 patients with moderate-to-severe periodontal diseases. Clinical periodontal records and grey level (GL) score based on digital subtraction radiography were measured on the day of denture placement (baseline) and at 1day, 1 week, 1 month, 3 months, and 6 months after the placement. Occlusal force on total dentition (Ft) and abutment tooth (Fa) were recorded with (baseline) and without denture on the day of the placement, and with denture in the follow-up examinations. No statistically significant difference between a follow-up period and the baseline was found in the clinical periodontal and occlusal force records, except for Ft with denture on the day of the placement, which was significantly lower than the baseline (p<0.05). The GL at distal crestal of the abutment...