Effects of implant placement timing and type of soft-tissue grafting on histological and histomorphometric outcomes in a preclinical canine model.

AIM: To determine the effects of implant timing and type of soft-tissue grafting on histological and histomorphometric outcomes in a preclinical model. MATERIALS AND METHODS: Four implant placement protocols were randomly applied at the mesial root sites of the third and fourth mandibular premolars in 10 mongrel dogs: immediate placement (group IP), early placement (group EP), delayed placement with/without alveolar ridge preservation (groups ARP and DP, respectively). A connective-tissue graft (CTG) or porcine-derived volume-stable collagen matrix (VCMX) was applied to enhance the ridge profile (simultaneously with implant placement in group IP and staged for others), resulting in five sites for each combination. All dogs were sacrificed 3 months after soft-tissue grafting. Histological and histomorphometric analyses were performed, and the data were analysed descriptively. RESULTS: CTG and VCMX were difficult to differentiate from the augmented area. The median total tissue thickness on the buccal aspect of the implant was largest in group IP/CTG (between 2.78 and 3.87 mm). The soft-tissue thickness was generally favourable with CTG at all implant placement timings. Within the DP groups, CTG yielded statistically significantly larger total and soft-tissue thickness than VCMX (p < .05). Among the groups with VCMX, group EP/VCMX showed the largest soft-tissue thickness at apical levels to the implant shoulder. CONCLUSIONS: CTG generally led to greater tissue thickness than VCMX.

Association between dietary quality and the prevalence of periodontitis in older Korean adults aged 60 or over.

PURPOSE: This study investigated the association between dietary quality and the prevalence of periodontitis in older Korean adults (≥60 years of age) using data from the seventh Korea National Health and Nutrition Examination Survey (KNHANES VII, 2016-2018). METHODS: Among the 16,489 KNHANES participants from 2016-2018, those aged ≥60 years were selected as the eligible population. After applying our exclusion criteria, 3,527 participants were included in the final study population. Periodontal status was measured using the Community Periodontal Index (CPI). To determine the association between dietary quality and the prevalence of periodontitis, analysis of variance, the chi-square (χ²) test, and logistic regression analysis were performed. RESULTS: The population was divided into quartile groups and stratified by sex. The percentage of men and women with periodontitis was 54.34% and 42.74%, respectively. The quartile with higher Korean Healthy Eating Index scores had a lower percentage of people with periodontitis in both sexes. For men, only vegetable intake showed a significant difference between sub-groups with or without periodontitis, whereas, for women, the intake of fruits, milk, sweets, carbohydrates, and fats showed significant differences. There was a strong positive association between vegetable intake and periodontitis in men in the 3 models used in this study; model 3 had an adjusted odds ratio (aOR) of 1.367 (95% confidence interval [CI], 1.091-1.712). In women, a strong positive association with periodontitis was shown for sweets in all 3 models, with an aOR of 1.477 in model 3 (95% CI, 1.125-1.939). CONCLUSIONS: Dietary quality was inversely associated with the prevalence of periodontitis in Korean adults aged ≥60 years. Further comprehensive studies are needed to help establish nutrition and health policies for older adults in Korea.

Keratinized tissue augmentation using collagen-based soft tissue substitute with/without epidermal growth factor on buccally positioned implants: a pilot preclinical study.

OBJECTIVES: To investigate the effect of epithelial growth factor (EGF) with collagen matrix (CM) on the gain of KT for buccally positioned implants in dogs. MATERIALS AND METHODS: In five dogs, four implants were placed buccally with the whole part of KT excision on the buccal side (two implants per each hemi-mandible). After one month, KT augmentation was performed: 1) free gingival grafts (FGG), 2) collagen matrix (CM) only, 3) CM soaked with 1 µg/g of EGF, and 4) CM soaked with 10 µg/g of EGF (n = 5 in each group). The experimental animals were sacrificed three months post-KT augmentation. Clinical, histologic, and histomorphometric analyses were performed. RESULTS: The clinical KT zone was the highest in group FGG (5.16 ± 1.63 mm). Histologically, all groups presented buccal bony dehiscence. Regarding newly formed KT, no specific difference was found among the groups, but robust rete pegs formation in some specimens in group FGG. Histomorphometric KT height (4.66 ± 1.81 mm) and length (5.56 ± 2.25 mm) were the highest in group FGG, whereas similar increases were noted in the rest. The buccal soft tissue thickness at the coronal part of the implant did not exceed 2 mm in all groups. CONCLUSION: All groups presented increased KT zone, but FGG treatment was more favored. The addition of EGF to CM appeared not to enhance KT formation. CLINICAL RELEVANCE: FGG treatment was more favorable to re-establish the KT zone than other treatment modalities.

Soft tissue outcomes following alveolar ridge preservation with/without primary flap closure for periodontally damaged extraction socket: A randomized clinical trial.

INTRODUCTION: The changes in soft tissue profile following alveolar ridge preservation (ARP) with/without primary flap closure (PC) in periodontally damaged sockets have yet to be discovered. METHODS: For periodontally damaged non-molar extraction sockets, ARP with PC (group PC)/without PC (group SC) was performed using granule-type xenogeneic bone substitute material and a collagen barrier. Intraoral scans were performed at the time of ARP and 4 months thereafter. Superimposition of STL files was performed to examine tissue change on the soft tissue level. The level of mucogingival junction (MGJ) was also evaluated. RESULTS: A total of 28 patient (13 in group PC, 15 in group SC) completed the study. Soft tissue profile change was evaluated only when the measurement level was located on the non-mobile tissue. Group PC tended to shrink less on the long axis of the extraction socket than group SC (-4.3 ± 3.1 mm vs. -5.9 ± 4.4 mm at the 1 mm below the pre-extraction gingival margin, p > 0.05). Profilometric analysis (on the region of interest) also have a tendency of less tissue profile change in group PC than group SC (-1.0 ± 0.8 mm vs. -1.3 ± 0.5 mm, p > 0.05). The MGJ level change was not statistically significantly different between the groups (p > 0.05) even though the MGJ level was located more apically at 4 months in group SC compared with group PC. CONCLUSIONS: Alveolar ridge preservation with PC tended to yield less soft tissue shrinkage than ARP without PC.

Primary flap closure in alveolar ridge preservation for periodontally damaged extraction socket: A randomized clinical trial.

INTRODUCTION: The effect of primary wound closure (PC) on alveolar ridge preservation (ARP) in periodontally damaged sockets has yet to be fully discovered. METHODS: Periodontally damaged sockets were allocated to one of the following groups: (1) ARP with PC (group PC), and (2) ARP without PC (group secondary wound closure [SC]). Following tooth extraction and flap elevation, granule-type xenogeneic bone substitute material and a collagen barrier were applied. Ridge change was evaluated using cone-beam computed tomographic (CBCT) scans immediately after ARP and at 4 months. Core biopsy specimens were examined histomorphometrically. RESULTS: A total of 28 patients were included in the analysis (13 in group PC, 15 in group SC). Histomorphometrically, the percentage of newly formed bone was 26.2 ± 17.7% and 24.6 ± 18.4% in groups PC and SC, respectively (independent t-test, degree of freedom [df] = 25, p > 0.05). Horizontal ridge changes on CBCT were -4.9 ± 3.1 mm and - 4.2 ± 2.5 mm in groups PC and SC at the 1 mm level below the ridge crest, respectively (independent t-test, df = 26, p > 0.05). Approximately half of the sites required additional bone augmentation at implant placement. CONCLUSIONS: ARP with/without PC yielded similar new bone formation and radiographic ridge change. This clinical trial was not registered prior to participant recruitment and randomization (https://cris.nih.go.kr/cris/search/detailSearch.do/19718).

Dimensional ridge changes in conjunction with four implant timing protocols and two types of soft tissue grafts: A pilot pre-clinical study.

AIM: To determine the effect of (1) implant placement timing and (2) the type of soft tissue graft in terms of ridge profile changes. MATERIALS AND METHODS: Four implant treatment modalities were applied in the mesial root areas of the third and fourth mandibular premolars of 10 mongrel dogs alongside connective-tissue graft (CTG) and volume-stable cross-linked collagen matrix (VCMX): immediate, early, and delayed placement (DP), and DP following alveolar ridge preservation (ARP). All dogs were sacrificed 3 months after soft tissue augmentation. Standard Tessellation Language files from designated time points were analysed. RESULTS: Compared with the pre-extraction situation, the median width of the ridge demontstrated a linear increase only in group ARP/CTG (0.07 mm at the 2-mm level), whereas all other groups showed a reduction (between -1.87 and -0.09 mm, p > .05). Groups ARP/CTG (0.17 mm) and DP/CTG (0.05 mm) exhibited a profilometric tissue gain in a set region of interest (p > .05). The net effect of CTG and VCMX ranged from 0.14 to 0.79 mm. CONCLUSIONS: Dimensional ridge changes varied between treatment protocols. ARP with CTG led to the smallest difference in ridge profile between the pre-extraction and the study end time point. Both CTG and VCMX enhanced the ridge contour.

Effectiveness of hydraulic pressure-assisted sinus augmentation in a rabbit sinus model: a preclinical study.

OBJECTIVES: To investigate the effectiveness of hydraulic pressure-assisted sinus augmentation (SA) in a rabbit sinus model in terms of radiographical and histological healing. MATERIALS AND METHODS: Bilateral SA was performed in 12 rabbits. Each sinus was randomly assigned to either a hydraulic pressure-assisted SA (test) or a conventional SA (control) group. Healing periods of 2 and 4 weeks were applied (n = 6 for each week). Healing pattern including newly formed bone (NB) and residual bone substitute material (RM) was analyzed with microcomputed tomographically, histologically, and histomorphometrically. RESULTS: No sinus membrane perforation was detected in either group. In the microcomputed tomographic analysis, the test group exhibited higher apico-coronal spread of RM compared to the control group (p < 0.05). Particularly, the test group exhibited several masses of NB out of the cluster of RM. Histologically, the test group showed an elongated shape of the augmented space, whereas the control group generally presented a dome shape. Histomorphometrically, the total augmented area and the area of NB (1.32 ± 0.56 vs. 0.84 ± 0.40 mm2 at 2 weeks, 2.24 ± 1.09 vs. 2.22 ± 0.85 mm2 at 4 weeks) were not significantly different between the test and the control groups at both healing periods (p > 0.05). CONCLUSION: Hydraulic pressure-assisted SA led to new bone formation in the distant areas from the bony access hole, but similar histological healing pattern to conventional SA. CLINICAL RELEVANCE: Hydraulic pressure-assisted SA is a promising option for treating pneumatized posterior maxilla.

A case series of profilometric changes in two implant placement protocols at periodontally compromised non-molar sites.

Information regarding profilometric changes at a soft tissue level following implant placement with different protocols is insufficient. Therefore, this study aimed to comparatively investigate the profilometric tissue changes with respect to late implant placement following alveolar ridge preservation (LP/ARP) and early implantation (EP) in periodontally compromised non-molar extraction sites. Sixteen patients were randomly assigned to the following groups: implant placement 4 months post-ARP (group LP/ARP) and tooth extraction and implant placement 4-8 weeks post-extraction (group EP). Dental impressions were obtained immediately after final prosthesis insertion and at 3, 6, and 12 months. At the time of implant placement, bone augmentation was performed in the majority of the patients. Profilometric changes of the tissue contour were minimal between the final prosthesis insertion and 12 months in the mid-facial area (0.04-0.35 mm in group LP/ARP, 0.04-0.19 mm in group EP). The overall tissue volume increased in both groups (1.70 mm3 in group LP/ARP, 0.96 mm3 in group EP). In conclusion, LP/ARP and EP led to similar stability of the peri-implant tissue contour between the final prosthesis insertion and at 12 months. Moreover, the change of peri-implant tissue on the soft tissue level was minimal in both modalities.

Collagenated Synthetic Bone Substitute Material for Sinus Floor Elevation at Sites with a Perforated Schneiderian Membrane.

Schneiderian membrane perforation (SMP) is the most common complication during sinus floor elevation (SFE). Conventional methods to repair SMP, such as using a collagen barrier, may be clinically demanding. The aim of the present study was to compare the effects of collagenated bone substitute materials with and without a collagen barrier to repair SMP during SFE in terms of new bone formation and dimensional stability. In 12 rabbits, intentional SMP was made during bilateral SFE. The rabbits were randomly assigned under two groups: the control group, in which the sinus was repaired with a collagen barrier, and the test group, in which the sinus was repaired without a collagen barrier. Collagenated bone substitute material was grafted in both groups. Healing periods of 2 weeks and 4 weeks were provided in both groups. There were no adverse clinical events. Histology revealed that the Schneiderian membrane had atrophied with loss of cilia and serous glands in both groups at 4 weeks. Histomorphometry revealed that the newly formed bone (test: 0.42 ± 0.17 mm2, control: 0.36 ± 0.18 mm2 at 2 weeks; test: 1.21 ± 0.36 mm2, control: 1.23 ± 0.55 mm2 at 4 weeks) or total augmented area did not significantly differ between the two groups at either time points (p > 0.05). In conclusion, collagenated bone substitute material without a collagen barrier demonstrated similar new bone formation and dimensional stability as that with a collagen barrier in repairing SMP.

Relationships between cognitive function and frailty in older Korean adults: The moderating effect of the number of teeth.

BACKGROUND: Cognitive function and physical frailty are known to be closely related. Among older adults with dementia, those who wear dentures have a higher mortality rate than those who do not wear them. This suggests the possibility that oral health may affect the cognitive-frailty relationship. This study aims to investigate whether the number of teeth present, acts as a moderating variable in the cognitive function-frailty relationship. METHODS: Data were obtained from the cross-sectional baseline study of the Korean Frailty Aging Cohort Study (2016-2017). Cognitive function was assessed using the Mini-Mental State Examination. Frailty score was based on the Cardiovascular Health Study Index. Oral condition was evaluated by the number of teeth present and analyzed using categories of 0-9 teeth, 10-19 teeth, and ≥20. The moderation effect was analyzed using the ordinary least squares (OLS) regression. RESULTS: Data on 2,310 older adults (1,110 men; mean age 75.9 ± 3.9 years) was analyzed. Adjusting for age, sex, income, education, alcohol drinking, body mass index, and number of comorbidities, cognitive function and frailty showed a negative association (B=-.030, p = .011). In the 10-19 teeth category, compared to the 0-9 teeth category, a negative association with frailty was found (B=-.152, p = .026). A significant interaction effect between the number of teeth and cognitive function was detected (p = .007). CONCLUSION: The number of teeth may modify the degree of the association between cognitive function and frailty. For effective frailty management of older persons, cognitive function management and oral management should be considered and performed together.

Late implant placement following ridge preservation versus early implant placement: A pilot randomized clinical trial for periodontally compromised non-molar extraction sites.

AIM: To compare late implant placement following alveolar ridge preservation (LP/ARP) and early implantation (EP) in periodontally compromised non-molar extraction sites with respect to soft tissue levels, aesthetics, and patient-reported outcomes. MATERIALS AND METHODS: Sixteen patients were randomly allocated to groups LP/ARP (n = 9) or EP (n = 7). Group LP/ARP received ARP using deproteinized bovine bone mineral containing 10% collagen and a native bilayer collagen membrane, and group EP received only extraction. Implant placement was performed 4-8 weeks post-extraction in group EP and 4 months post-alveolar ridge preservation in group LP/ARP. The soft tissue levels, pink/white esthetic scores, and periodontal parameters were evaluated at 1 year post-loading. Patient's discomfort level was evaluated in terms of extraction/ARP and implant placement. RESULTS: No implant failure or biologic complications occurred. There was no statistically significant difference in the median change of the midfacial mucosal margin (0.03 for group LP/ARP, -0.19 mm for group EP) and the mesial/distal papilla (0.62/0.25 mm for group LP/ARP, 0.29/-0.5 mm for group EP), pink/white esthetic scores, periodontal parameters, and patient's discomfort between the two groups. CONCLUSION: Both implant placement protocols led to comparable outcomes in soft tissue levels, periodontal parameters, and patient's discomfort level.

Cone-beam computed tomographic analysis of the alveolar ridge profile and virtual implant placement for the anterior maxilla.

PURPOSE: To analyze the ridge profile of the anterior maxilla using cone-beam computed tomography and to assess the clinical significance of the ridge profile by performing virtual implant placement. METHODS: Thirty-two cone-beam computed tomography scans of anterior maxillae were included. For each tooth, a vertical line was made along the longitudinal axis, and 3 horizontal lines at 1-, 3-, and 5-mm levels below the labial bone crest were drawn perpendicularly to the vertical reference. At these levels, the thickness of the alveolar ridge (RT), and the labial (LT) and palatal bone plate (PT) were measured. Then, virtual implant placement using standard and tapered implants was performed. A generalized linear mixed model was used for statistical analysis. RESULTS: The teeth were located labially based on the proportion of LT and PT with respect to RT. At the 1-mm level, the value of LT was between 1.0±0.4 mm for central incisors and 1.3±0.6 mm for canines. A large number of teeth had area(s) with less than 1-mm-thick labial bone between the 1- and 5-mm levels below the crest. The mean PT was generally thicker than the LT in all tooth types. The greatest mean value of labial concavity was observed for canines, compared to other tooth types. Men had a greater RT than did women, but had a comparable LT. Less apical fenestration was observed when tapered implants were used. CONCLUSIONS: Most teeth in the anterior maxilla had a thin labial bone plate, with no significant difference between sexes. Tapered implants may be advantageous for the anterior maxilla.

Primary stability of implants with peri-implant bone defects of various widths: an in vitro investigation.

PURPOSE: This study aimed to evaluate the effects of i) the extent of peri-implant bone defects and ii) the application of bone cement on implant stability with respect to the measurement direction. METHODS: In 10 bovine rib bones, 4 implant osteotomies with peri-implant bone defects of various widths were prepared: i) no defect (D0), ii) a 2-mm-wide defect (D2), iii) a 4-mm-wide defect (D4), and iv) a 8-mm-wide defect (D8). The height of all defects was 10 mm. Implant stability quotient (ISQ) values and Periotest values (PTVs) were measured after implant placement and bone cement application. RESULTS: With increasing defect width, decreased ISQs and increased PTVs were observed. Statistically significant differences were found between groups D0 and D8, D0 and D4, and D2 and D8. Prior to bone cement application, inconsistent PTVs were found in group D8 depending on the measurement direction. Bone cement increased the implant stability. CONCLUSION: Peri-implant bone deficits measuring around 50% of the implant surface compromised implant stability. Clinically, PTVs should be cautiously interpreted in implants with large peri-implant defects due to inconsistent recordings with respect to the measurement direction.

Enhanced Bone Regeneration by Diabetic Cell-Based Adenoviral BMP-2 Gene Therapy in Diabetic Animals.

The application of bone morphogenetic protein 2 (BMP-2) has been extensively investigated to improve diabetes-impaired bone healing; however, the delivery of BMP-2 by gene therapy for bone regeneration has rarely been investigated in diabetic animals. In this study, we aimed to evaluate which cells induce more new bone formation in diabetic animals when cell-based BMP2 gene therapy is applied. For this purpose, we harvested bone marrow stromal cells (BMSCs) twice in the same animal before (non-diabetic BMSCs; nBMSCs) and after diabetes induction (diabetic BMSCs; dBMSCs) using modified bone marrow ablation methods. And then, cells were transduced by adenoviral vectors carrying the BMP2 gene (AdBMP2). In in vitro, AdBMP2-transfected dBMSCs (B2/dBMSCs) produced higher BMP-2 mRNA levels over 48 h, whereas AdBMP2-transfected nBMSCs (B2/nBMSCs) exhibited a transient increase in BMP-2 mRNA followed by a decrease to the baseline level within 48 h. Both B2/dBMSCs and B2/nBMSCs induced secretion of BMP-2 for 3 weeks. However, B2/dBMSC BMP-2 secretion peaked from day 3 to 10, whereas B2/nBMSC BMP-2 secretion peaked from day 1 to 7. The analysis of osteogenic activity revealed that mineralization nodule formation and the expression levels of osteogenic genes were significantly higher in B2/dBMSCs than B2/nBMSCs and were accompanied by upregulation of canonical Wnt/ß-catenin and Smad signaling. AdBMP2-transfected autologous cells were implanted into critical-sized calvarial defects in diabetic animals and induced significantly more bone regeneration than non-AdBMP2-transfected cells. In addition, B2/dBMSCs led to significantly more new bone formation than B2/nBMSCs. Thus, BMP2 gene therapy using diabetic cells effectively supported diabetic bone healing and it was related to the enhanced responses to AdBMP2 of dBMSCs.

Validity of Collagen Plugs for Ridge Preservation in a Canine Model.

PURPOSE: The purpose of the present study was to evaluate healing outcomes after collagen plug insertion in extraction-related defects. MATERIALS AND METHODS: The third and fourth mandibular premolars in canines were extracted, and the septal bone was removed. The following treatments were performed for the defects: porcine atelo-collagen plug, bovine atelo-collagen plug, and no intervention (control). The experimental animals were killed after 6, 12, or 24 weeks (n = 4, respectively). Histologic and histomorphometric analyses were performed. RESULTS: Clinical healing was uneventful, and no difference was detected among the 3 groups. Histologically, similar healing patterns were observed in all groups. Gingival healing was complete at 6 weeks, but discontinuity in the buccal crestal bone was observed. At 12 weeks, various degrees of buccal bone depression and increase in bone marrow were observed. At 24 weeks, no further healing was observed. Histomorphometrically, the ridge width at 1, 3 and 5 mm levels below the crest and the ridge dimensions 1, 3, and 5 mm above the level were not statistically different among groups or healing periods. CONCLUSION: The healing following the use of collagen plug in the extraction socket may correspond to the natural healing after extraction.