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.

An observational study of oral functions in patients aged from 20 to 49 years.

PURPOSE: The purpose of this study was to analyze oral functions (MOF: maximum occlusal force; MTP: maximum tongue pressure; and MF: masticatory function) in Eichner A subjects aged from 20 to 49 years. METHODS: The data of three oral functions in Eichner A patients aged from 20 to 49 years were extracted. The mean values, subjects with lower values than the thresholds, and the differences among ages, and between sexes were investigated retrospectively. RESULTS: Although the mean values of these oral functions in 183 subjects were higher than the thresholds, the numbers of the subjects with lower values than the thresholds were 30 in MTP, 19 in MOF, and only three in MF. No significant effects of ages on all oral functions were identified and all functions in males were significantly higher than those in females. The subjects whose two functions were lower than the thresholds were nine females, eight of whom were associated with malalignment. CONCLUSION: Although the mean values of oral functions were higher than the thresholds, some patients showed lower values, especially in MOF and MTP, even though they were unaware of any inconvenience. Patients with malalignment might be associated with declined oral functions.

Anterior Hyperfunction by Mandibular Anterior Teeth: A Narrative Review.

"Combination syndrome", defined by Kelly in 1972, is a challenging condition observed in a patient with an edentulous maxilla and a partially edentulous mandible with only mandibular anterior teeth. "Anterior hyperfunction syndrome" is regarded as a synonym of combination syndrome and was first described in 1994. Although these terms have been well known, the definition of "anterior hyperfunction" has not been described yet. This narrative review focused on anterior hyperfunction and discussed the etiology and the clinical managements. An electronic bibliographic search for this literature review was conducted in addition to the review of our clinical cases. The previous reports indicated that combination syndrome with all five features was rarely observed. The patients with anterior hyperfunction generally showed the loss of posterior occlusal supports and the loss of vertical dimension of occlusion. To manage anterior hyperfunction, these conditions should be improved using conventional removable prostheses and implant-supported prostheses. Anterior hyperfunction is attributed to mandibular anterior teeth and some interventions for mandibular anterior teeth are required in many cases. Additionally, it must be noted that implant-supported prostheses may lead to anterior hyperfunction. In conclusion, comprehensive approaches for the remaining teeth and the prostheses will be required to manage this complex condition.

Comprehensive Analyses of Masticatory Function in Maxillectomy Patients with Functioning Removable Prostheses: A Retrospective Cross-Sectional Study.

The aim of this retrospective cross-sectional study was to comprehensively assess masticatory function in maxillectomy patients with functioning removable prostheses. Their general and oral profiles, the measurement values of their oral functions, including masticatory function, and the history of tumor therapy were extracted from medical charts. The correlations of masticatory function with numerical data and the effects of tumor therapy-related factors on masticatory function were evaluated. In addition, a stepwise conditional logistic regression analysis was performed to identify the potential predictive factors comprehensively. The data from 55 maxillectomy patients revealed that the median value of masticatory function (138.0 mg/dL) was higher than the threshold (100.0 mg/dL) based on the concept of oral hypofunction. Moderate correlations of masticatory function with the number of remaining teeth, the number of functioning occlusal supports, and maximum occlusal force were found, as well as a weak correlation with maximum tongue pressure. These variables also showed statistically significant coefficients (p < 0.01). No significant effect of each tumor therapy-related factor on masticatory function was detected. A logistic regression analysis identified the number of functioning occlusal supports as a significant predictive factor. These results implied the crucial interactions of masticatory function with various factors and the specificities of maxillectomy patients.

Oral Rehabilitation from Oral and Dental Diseases.

Oral conditions, such as the number of teeth and oral hygiene, are related to oral functions and oral health-related quality of life (QoL) [...].

Primary stability of different implant macrodesigns in a sinus floor elevation simulated model: an ex vivo study.

BACKGROUND: A novel type of implant (Straumann® BLX implant) has been developed for certain stability from the mechanical and biological aspects and is expected for the implant placement in atrophic maxilla with sinus floor elevation (SFE). PURPOSE: The aim of this study was to evaluate the primary stability in the implants with different macrodesigns in an SFE simulated model. Primary stabilities defined as maximum insertion torque (MIT) and implant stability quotient (ISQ) were compared between this novel type of implant and other types. MATERIALS AND METHODS: Five types of Straumann® 10 mm length implants (Standard Plus; SP, Tapered Effect; TE, Bone Level; BL, Bone Level Tapered; BLT and BLX) and two types of Straumann® 6 mm length implants (SP short, BLX short) were used in this study. Each implant was inserted through 5 mm-thick porcine iliac crest blocks (an SFE simulated model). Primary stability was evaluated by using MIT and ISQ. RESULTS: The mean value of MIT for BLX group showed significantly higher values than SP, BL (p < 0.01), and TE (p < 0.05) groups. The mean value of ISQ for BLX group was significantly higher than the other groups (p < 0.01). The mean value of MIT and ISQ for BLX and BLX short group were significantly higher than those for SP and SP short group (p < 0.01). CONCLUSIONS: In an SFE simulated ex vivo model, BLX group showed the highest values. These results suggest that implant selection can play a crucial role in the achievement of primary stability during SFE and simultaneous implant placement.

Clinical effectiveness of implant support for distal extension removable partial dentures: functional evaluation using occlusal force measurement and masticatory efficiency.

BACKGROUND: Implant-supported removable partial dentures (ISRPD) are supported at the free-end region with implant retainers. As implant retainers prevent denture settlement and facilitate denture retention, this is intended to improve masticatory performance in comparison with that of conventional removable dentures. In the present study, we evaluated the effect of implant retainers at the free-end region of removable dentures on occlusal force and masticatory efficiency using a pressure-sensitive sheet, and measured glucose concentration in saliva after mastication with gummy candy. METHODS: In the present study, the occlusal force and masticatory efficiency of 13 subjects were measured in the following three conditions: without dentures (Condition 1), wearing dentures but not supported by implants (Condition 2), and wearing dentures supported by implants (ISRPD) (Condition 3). All data were statistically compared. RESULTS: Regarding the occlusal force, Condition 3 showed significantly higher scores than the other conditions; however, there were no significant differences between Conditions 1 and 2. Regarding the masticatory efficiency, Condition 3 showed significantly higher scores than Condition 2. CONCLUSIONS: With ISRPD, the occlusal force and masticatory efficiency were increased in comparison with those with conventional removable dentures.

Staged Sinus Floor Elevation Using Novel Low-Crystalline Carbonate Apatite Granules: Prospective Results after 3-Year Functional Loading.

The aim of this study was to evaluate clinical outcomes of staged sinus floor elevation (SFE) using novel low-crystalline carbonate apatite (CO3Ap) granules. Patients who needed SFE for implant placement were recruited into this clinical trial. A staged procedure (lateral window technique using CO3Ap granules, followed by implant placement after 7 ± 2 months) was employed in 13 patients. Bone-height increase and insertion torque values (ITVs) were assessed along with histological evaluation. The survival and success rates of 3-year functioning implants were also evaluated. Mean of bone-height increase after SFE using CO3Ap granules was 7.2 ± 2.5 mm and this increase allowed implant placement in all cases (17 implants). Mean of ITV was 25.1 ± 13.2 Ncm and primary stability was achieved successfully in all cases. Histological analyses revealed mature new bone formation (36.8 ± 17.3%) and residual CO3Ap granules (16.2 ± 10.1%) in the compartment after SFE. The survival and success rates after 3-year functional loading were 100% and no complications were found. These results clearly indicate the clinical usefulness of CO3Ap granules for SFE.

Masticatory performance and other oral functions in community-dwelling elderly patients without posterior occlusal support by natural teeth.

PURPOSE: To evaluate masticatory performance (MP), maximum occlusal force (MOF), maximum tongue pressure (MTP) and oral diadochokinesis (ODK) among community-dwelling elderly patients without posterior occlusal support. METHODS: This study enrolled community-dwelling elderly patients (≥65 years old) who belonged to Eichner A, B4, C1, C2, and C3. Each oral function was statistically compared among groups. Correlations between MP and other variables were examined in Eichner B4 and C patients. RESULTS: MP and MOF values in Eichner B4 and C patients were significantly lower than in Eichner A patients. There were significant differences in MTP values between Eichner "A and C2, C3", and "B4 and C2, C3". ODK in Eichner C patients showed significantly lower values compared to Eichner A patients in general. Although there were statistically significant correlations of MP with age, the number of remaining teeth and all oral functions were identified, and multiple regression analysis indicated that MOF and MTP were independently related to MP. CONCLUSION: Oral functions in Eichner B4 and C patients were lower compared to Eichner A patients. MP was significantly correlated with MOF and MTP in elderly patients without posterior occlusal support, suggesting the importance of rehabilitation of MOF and MTP in MP.

Analyses of Swallowing Function and Its Related Factors in Community-Dwelling Elderly Patients: A Case-Control Study.

This retrospective case-control study evaluated the prevalence of declined swallowing function and the association with oral functions and gender in community-dwelling elderly patients. Their profiles, the results of swallowing function (Eating Assessment Tool: EAT-10) and other oral functions (oral dryness, maximum occlusal force (MOF), tongue-lip motor function (oral diadochokinesis: ODK), maximum tongue pressure (MTP) and masticatory performance (MP)) were extracted for analyses. The patients were categorized into three groups according to EAT-10 score (Group 1: 0, Group 2: 1 and 2, Group 3: ≥3). In total, 242 patients were enrolled and 46 of them (19.0%) were categorized into declined swallowing function (Group 3). In two-group comparisons (Group 1, 2 versus Group 3), significant differences were identified in age and the number of remaining teeth, but they were not identified in three-group comparisons. The patients with declined swallowing function (Group 3) had significantly lower function in ODK and MTP. Multiple logistic regression analyses identified that declined swallowing function was independently associated with declined functions in ODK /ka/ (OR: 5.31, 95% CI: 1.03-27.23, p = 0.04) and in MTP (OR: 2.74, 95% CI: 1.12-6.66, p = 0.03). This study could confirm the critical role of tongue functions in swallowing in community-dwelling elderly patients.

A Prospective Comparative Study of Mastication Predominance and Masticatory Performance in Kennedy Class I Patients.

Mastication predominance in Kennedy class I (KC I) patients has not been well defined. This study aimed to investigate mastication predominance and masticatory performance in KC I patients, including the significance of remaining posterior teeth and removable partial-denture (RPD) treatment. KC I patients who had differences in the number of posterior teeth between left and right sides (D+) and KC I patients who had no differences (D-) were enrolled. Healthy dentate (HD) subjects were also registered as a positive control. Mastication predominance, defined by mastication predominance index (MPI; range 0-100%) calculated from electromyogram activities during voluntary chewing, and masticatory performance were evaluated at pre- and post-RPD treatment. Pre-MPI in KC I D+ was significantly higher than in HD. RPD treatment could significantly improve MPI and masticatory performance in both KC I groups. However, there were significant differences in masticatory performance between each KC I group and HD, regardless of RPD treatment. It was considered that the mastication predominance in KC I patients was affected by the difference in the number of remaining posterior teeth. RPD treatment could improve mastication predominance and masticatory performance in KC I patients, although the latter was not similar to HD group.

The Significance of Posterior Occlusal Support of Teeth and Removable Prostheses in Oral Functions and Standing Motion.

The purpose of this study was to evaluate the effect of posterior occlusal support of natural teeth and artificial teeth on oral functions and standing motion. Patients who had been treated with removable prostheses were enrolled as the subjects. Their systemic conditions (body mass index (BMI) and skeletal muscle mass index (SMI)) were recorded. The subjects were classified into two groups according to a modified Eichner index: B1-3 (with posterior occlusal support) and B4C (without posterior occlusal support). Maximum occlusal force (MOF), masticatory performance (MP), and standing motion (sway and strength) were evaluated for cases with and without removable prostheses. There were no significant differences in BMI and SMI between the B1-3 group and the B4C group. The subjects with removable prostheses demonstrated significantly higher values in MOF, MP, and sway and strength than the subjects without removable prostheses. The comparison of oral functions between the B1-3 group and the B4C group revealed that the positive effect of posterior occlusal support of natural teeth and removable prostheses and the significant positive effects of posterior occlusal support on standing motion were partly observed in these comparisons. Posterior occlusal support of natural teeth and even of removable prostheses may contribute to the enhancement of oral functions and standing motion.

A 3-Year Prospective Study on Radiographic Marginal Bone Evaluation Around Platform-Shifting Implants with Internal Conical Connections.

PURPOSE: To evaluate marginal bone level changes over 3 years around platform-shifting implants with internal conical connections, and to identify the factors relating to bone level changes. MATERIALS AND METHODS: Systemically healthy patients who lost one tooth or two consecutive teeth were enrolled in the study. The subjects received one or two implants with platform-shifting and internal conical connections in healed bone in a submerged manner. Digital standardized periapical radiographs were obtained at the time of implant placement, at prosthesis delivery, at 1 year, and at 3 years after the definitive restorations. Marginal bone level changes were measured at the mesial and distal aspects of each implant. Spearman correlation coefficients were calculated to examine the correlation between marginal bone level changes and clinical factors (age, vertical mucosal thickness, implant length and diameter, insertion torque value, and vertical implant position). RESULTS: Twenty-five patients with 30 implants (8 men and 17 women, mean age: 61.24 ± 13.18 years) were followed up to 3 years after the definitive restorations. The implant survival rate was 100%, and no remarkable complications were found. Mean peri-implant marginal bone level changes were -0.41 ± 0.61 mm (from placement to prosthesis delivery: C1); -0.08 ± 0.54 mm (from prosthesis delivery to 1 year: C2); -0.04 ± 0.95 mm (from prosthesis delivery to 3 years: C3); and 0.04 ± 0.60 mm (from 1 year to 3 years: C4), respectively. Statistically significant differences in bone level changes were observed between C1 and C3, and C1 and C4. Significant correlations of marginal bone level changes with implant diameter in C1 and with vertical implant position in C2 and C3 were observed. CONCLUSION: Within the limitations of this study, platform-shifting implants with internal conical connections appeared to prevent marginal bone resorption, especially after delivery of definitive prostheses, although marginal bone resorption attributed to the reestablishment of biologic width following subcrestal placement might be unavoidable.

In Vitro Assessment of the Effect of Implant Position on Biomechanical Behaviors of Implant-Supported Removable Partial Dentures in Kennedy Class II Condition.

The purpose of this study was to investigate the effects of implant position and loading position on biomechanical behaviors using implant-supported removable partial denture (ISRPD) models in a simulated Kennedy class Ⅱ partially edentulous mandible. Three types of Kennedy class Ⅱ mandibular acrylic resin models (a conventional RPD without support by an implant-CRPD; models with an implant placed at first molar (#46)-MP-ISRPD- and second molar (#47)-DP-ISRPD) were used to measure vertical displacement of the RPD, mesio-distal displacement of the abutment tooth, and bending moment of the abutment tooth and implant under one-point loading. The variables at three respective loading points (#45, #46 and #47) were compared statistically. Vertical displacement was suppressed in ISRPDs compared to the CRPD, and significant effects were identified under loading at the implant position. The largest meiso-distal displacement was observed in MP-ISRPD under #47 loading. Bending moments of the abutment tooth and implant were significantly higher in MP-ISRPD than in DP-ISPRD. In MP-ISRPD, a higher bending moment of the abutment tooth under #45 and #47 loading was detected, although the bending moment in DP-ISRPD was almost zero. The results of this study suggested that MP-ISRPD shows the specific biomechanical behaviors, although DP-ISRPD might provide biomechanical benefits under all one-point loading conditions.

A retrospective cross-sectional analysis of swallowing and tongue functions in maxillectomy patients.

PURPOSE: To investigate the profiles of swallowing and tongue functions, and to identify factors influencing swallowing in maxillectomy patients. METHODS: Maxillectomy patients whose swallowing function defined by Eating Assessment Tool (EAT-10) score and tongue functions (oral diadochokinesis: ODK, maximum tongue pressure: MTP) with or without obturator prostheses had been evaluated were enrolled in this study. The effects of the history of radiotherapy and soft palate defect on swallowing function were evaluated. The effect of radiotherapy on oral dryness was also evaluated. To examine correlations of swallowing function with continuous variables, Spearman correlation coefficients were calculated. RESULTS: A total of 47 maxillectomy patients (23 males and 24 females, median age: 71 [IQR: 63-76]) were registered. The median value of EAT-10 scores was 3 [IQR: 0-14]. Patients with the history of radiotherapy, but not with soft palate defect, showed significantly declined swallowing function. ODK and MTP of patients wearing obturator prostheses were significantly improved. No significant effect of radiotherapy on oral dryness was found. A significant correlation was found between EAT-10 score and MTP (P = 0.04). CONCLUSIONS: Swallowing function in maxillectomy patients was relatively impaired and the patients with the history of radiotherapy showed lower swallowing function. Obturator prostheses could contribute to the improvement of MTP and ODK (/ta/). MTP may play a crucial role in swallowing in maxillectomy patients.

Validation of masticatory function and related factors in maxillectomy patients based on the concept of "oral hypofunction": A retrospective cross-sectional study.

Purpose Although oral functions have been evaluated by various methods in maxillectomy patients, there exists substantial difficulty in the assessment procedures. The purpose of this study was to evaluate masticatory function, maximum occlusal force (MOF), and maximum tongue pressure (MTP) in maxillectomy patients objectively as per the "oral hypofunction" criteria, and examine the factors that correlate with masticatory function.Methods This retrospective cross-sectional study included 50 maxillectomy patients with maxillofacial prostheses (23 males and 27 females, median age, 72 years; interquartile range (IQR), 63.75-77). The records of masticatory function, MOF, and MTP as per the "oral hypofunction" criteria and their profiles (age, number of occlusal supports, and maxillary defect configuration) were reviewed. The number of patients who exceeded a threshold value of "oral hypofunction" and the effects of occlusal support and defect configuration on masticatory function and MOF were calculated. Multiple regression analysis was performed to assess the associations between masticatory function and other variables.Results The median value of masticatory function (114 mg/dL, IQR: 73-167.5) exceeded a threshold value, but not MOF (229.2 N, IQR: 110.2-419.6) and MTP (25.9 kPa, IQR: 21.4-29.0). The number of patients who exceeded each threshold value was 27 (masticatory function), 8 (MOF), and 12 (MTP), respectively. The influence of the number of occlusal supports, but not the defect configuration, was statistically significant. Multiple regression analysis revealed that MOF was independently related to masticatory function (P=0.042).Conclusions Within the limitations of this study, the median value of masticatory function in maxillectomy patients could exceed a threshold and MOF might be an independent predictor of masticatory function.

The impacts of prosthetic interventions on mastication predominance in Kennedy Class â ¡ patients.

Purpose The purpose of this study was to investigate the effects of prosthetic interventions in patients with Kennedy Class Ⅱ (unilateral missing posterior teeth) on mastication predominance.Methods The subjects comprised patients with Kennedy Class II and healthy dentate volunteers (HD group). The subjects were asked to freely chew the test foods (chewing gum, beef jerky, and peanuts). Electromyographic activity of the bilateral masseter muscles was recorded twice (before and after prosthetic intervention). The chewing side (right or left) was judged by the level of the root mean square electromyographic amplitude. Mastication predominance was assessed using the mastication predominance index (MPI; range 0-100%). Each patient was restored with a removable partial denture (RPD) or an implant-supported fixed prosthesis (IFP). The effects of prosthetic interventions were statistically evaluated by the differences between MPI before and after prosthetic interventions (pre-MPI and post-MPI , respectively).Results There was a significant difference between pre-MPI of patients with Kennedy Class II and MPI of the HD group (HD-MPI) for all test foods (P < 0.0001). Statistical analysis also demonstrated a significant difference between pre-MPI and post-MPI measured with each of the three food items in both the RPD and IFP groups (P < 0.0001). Multiple comparisons revealed that post-MPI in the IFP group, but not in the RPD group, was statistically comparable with HD-MPI, although there were no significant differences among the three groups when MPIs were calculated using peanuts.Conclusions Prosthetic interventions improved mastication predominance in patients with Kennedy Class Ⅱ patients. Depending on the food type, IFP might contribute to better improvement of mastication predominance than RPD depending on food.

Effect of Calcium Chloride Hydrothermal Treatment of Titanium on Protein, Cellular, and Bacterial Adhesion Properties.

Topographical modification of the dental implant surface is one of the main topics for the improvement of the material, however, the roughened surface has some risks for peri-implantitis. A hydrothermal treatment (HT) of titanium with calcium chloride solution was reported to improve osseointegration and soft tissue sealing without changing the surface topography; however, its mechanism is unclear. We herewith investigated the interaction between extracellular matrix (ECM) protein and HT titanium. Furthermore, we also clarified the bacterial interaction. We employed two kinds of HT, HT with water (DW-HT) and HT with calcium chloride solution (Ca-HT). As a result, the adsorptions of both laminin-332 and osteopontin onto the Ca-HT surface were enhanced. In contrast, the adsorption of albumin, which was reported to have no cell adhesion capacity, was not influenced by Ca-HT. Osteoblast adhesion onto Ca-HT was also enhanced. Although Ca-HT was reported to enhance both epithelial cell attachment strength and in vivo peri-implant epithelial bonding, the number of epithelial cell attachment was not increased even after HT. Ca-HT had no impact in the adhesion of Streptococcus gordonii. These results suggest that Ca-HT enhances cell adhesion onto titanium without increasing bacterial adhesion, and the improvement of ECM protein adsorption is supposed to contribute to cell adhesion.

Oral health-related quality of life and oral hygiene condition in patients with maxillofacial defects: A retrospective analysis.

PURPOSE: The purpose of this study was to evaluate the effect of oral rehabilitation (maxillofacial prosthetic intervention and oral hygiene instruction) on oral health-related Quality of Life (OHRQoL) and oral hygiene condition in patients with maxillofacial defects and to explore the correlation between them in these patients. METHODS: Twenty-five patients with maxillofacial defects who had been treated since April 2016 to March 2018 were included in this study. The scores of the Oral Health Impact Profile (OHIP) and O'Leary's Plaque Control Record (PCR) were also identified as the scores of OHRQoL and oral hygiene condition, respectively. Statistical analyses were performed to compare between the scores of "pre" and "post" prosthetic treatment and to evaluate patient-related factors influencing these variables (age, the number of residual teeth and occlusal supports, and occlusal units (OUs)). The effect of combined chemo-radiotherapy (CRT) on each score was also assessed statistically. Furthermore, the correlation of OHIP and PCR scores was explored statistically. RESULTS: Both oral rehabilitations could significantly improve OHIP and PCR scores. Significant correlations of the change of OHIP scores with age and OUs were detected. CRT had no significant effect on OHIP and PCR scores. No correlations between OHIP and PCR were observed. CONCLUSIONS: Although oral rehabilitation such as maxillofacial prosthetic treatment and oral hygiene instruction would be highly effective for improvement of OHRQoL and oral hygiene condition in patients with maxillofacial defects, there was no correlation between them.

Fabrication and Histological Evaluation of a Fully Interconnected Porous CO3Ap Block Formed by Hydrate Expansion of CaO Granules.

Carbonate apatite (CO3Ap) fabricated by a dissolution-precipitation reaction from a precursor exhibits excellent osteoconductivity and is readily replaced by bone. In the present study, a fully interconnected porous CO3Ap block was fabricated by hydrate expansion and carbonation of CaO granules, and the resulting CaCO3 was then converted to CO3Ap. When CaO granules were exposed to 100% humidity CO2 in a closed vessel, the CaO granules were hydrated and expanded to form a porous Ca(OH)2 block. The block was then carbonated to form a porous CaCO3 block, which was then immersed in a Na2HPO4 solution to convert it to a porous CO3Ap block. The resulting CO3Ap block possessed a fully interconnected porous structure. Histological analyses 4 and 8 weeks after implantation in rabbits revealed that the porous CO3Ap block resulted in more significant material resorption and bone formation than the dense CO3Ap block. Therefore, it was concluded that a fully interconnected porous CO3Ap block fabricated by the hydrate expansion of CaO granules has potential value as a bone substitute.