Soft-tissue volume augmentation using a connective tissue graft and a volume-stable collagen matrix with polydeoxyribonucleotide for immediate implant placement: a pilot study in a dog model.

PURPOSE: The aims of this study were 1) to investigate the effects of a subepithelial connective tissue graft (SCTG) and a volume-stable collagen matrix (VCMX) on soft-tissue volume gain in the immediate implant placement protocol, and 2) to determine whether polydeoxyribonucleotide (PDRN) can enhance the effects of a VCMX. METHODS: Dental implants were placed in 4 mongrel dogs immediately after extracting the distal roots of their third and fourth mandibular premolars. The gap between the implant and the buccal bone plate was filled with synthetic bone substitute particles. The following soft-tissue augmentation modalities were applied buccally: 1) control (no augmentation), 2) SCTG, 3) VCMX, and 4) VCMX/PDRN. After 4 months, histomorphometric analysis was performed. Tissue changes were evaluated using superimposed standard tessellation language (STL) files. RESULTS: Wound dehiscence was found in more than half of the test groups, but secondary wound healing was successfully achieved in all groups. Histomorphometrically, tissue thickness was favored in group SCTG at or above the implant platform level (IP), and group SCTG and the groups with VCMX presented similar tissue thickness below the IP. However, the differences in such thickness among the groups were minor. The keratinized tissue height was greater in group VCMX/PDRN than in groups SCTG and VCMX. Superimposing the STL files revealed a decrease in soft-tissue volume in all groups. CONCLUSIONS: Wound dehiscence after soft-tissue volume augmentation might be detrimental to obtaining the expected outcomes. PDRN appears not to have a positive effect on the soft-tissue volume gain.

Effect of polydeoxyribonucleotide with xenogeneic collagen matrix on gingival phenotype modification: a pilot preclinical study.

PURPOSE: To investigate the effect of xenogeneic collagen matrix (XCM) with polydeoxyribonucleotide (PDRN) for gingival phenotype modification compared to autogenous connective tissue graft. METHODS: Five mongrel dogs were used in this study. Box-type gingival defects were surgically created bilaterally on the maxillary canines 8 weeks before gingival augmentation. A coronally positioned flap was performed with either a subepithelial connective tissue graft (SCTG) or XCM with PDRN (2.0 mg/mL). The animals were sacrificed after 12 weeks. Intraoral scanning was performed for soft tissue analysis, and histologic and histomorphometric analyses were performed. RESULTS: One animal exhibited wound dehiscence, leaving 4 for analysis. Superimposition of STL files revealed no significant difference in the amount of gingival thickness increase (ranging from 0.69±0.25 mm to 0.80±0.31 mm in group SCTG and from 0.48±0.25 mm to 0.85±0.44 mm in group PDRN; P>0.05). Histomorphometric analysis showed no significant differences between the groups in supracrestal gingival tissue height, keratinized tissue height, tissue thickness, and rete peg density (P>0.05). CONCLUSIONS: XCM soaked with PDRN yielded comparable gingival augmentation to SCTG.

Retrospective analysis of keratinized tissue augmentation using a xenogeneic collagen matrix for resolving peri-implant mucositis and peri-implantitis.

PURPOSE: The significance of keratinized tissue for peri-implant health has been emphasized. However, there is an absence of clinical evidence for the use of a xenogeneic collagen matrix (XCM) to manage peri-implant mucositis and peri-implantitis. Therefore, the purpose of this study was to investigate outcomes after keratinized tissue augmentation using an XCM for the management of peri-implant diseases. METHODS: Twelve implants (5 with peri-implant mucositis and 7 with peri-implantitis) in 10 patients were included in this study. Non-surgical treatments were first performed, but inflammation persisted in all implant sites. The implant sites all showed a lack of keratinized mucosa (KM) and vestibular depth (VD). Apically positioned flaps with XCM application were performed. Bone augmentation was simultaneously performed on peri-implantitis sites with an intrabony defect (>3 mm). The following clinical parameters were measured: the probing pocket depth (PPD), modified sulcular bleeding index (mSBI), suppuration (SUP), keratinized mucosal height (KMH), and VD. RESULTS: There were no adverse healing events during the follow-up visits (18±4.6 months). The final KMHs and VDs were 4.34±0.86 mm and 8.0±4.05 mm, respectively, for the sites with peri-implant mucositis and 3.29±0.86 mm and 6.5±1.91 mm, respectively, for the sites with peri-implantitis. Additionally, the PPD and mSBI significantly decreased, and none of the implants presented with SUP. CONCLUSIONS: Keratinized tissue augmentation using an XCM for sites with peri-implant mucositis and peri-implantitis was effective for increasing the KMH and VD and decreasing peri-implant inflammation.

Infra- and labio-position of two maxillary central incisor implants in an older adult at a 17-year follow-up.

OBJECTIVE: This report aims to present an infra- and labio-version of the implants relative to the surrounding teeth in an older patient. BACKGROUND: Infra-positioning of dental implants has been sometimes observed in young adults but not in older patients. MATERIALS AND METHODS: Two implants were placed in both central incisor areas in a 63-year-old female patient in 2002. A splinted implant prosthesis was inserted six months later. RESULTS: After 17 years, a deviation in the position of the implant crown on the #21 area was 9.94 mm labially and 4.69 mm apically with respect to the adjacent tooth (#22). The corresponding values of the implant crown on the #11 area were 5.96 and 2.34 mm (with respect to #12), respectively. CONCLUSION: Dental implants in older adults might develop horizontal and vertical discrepancies relative to the neighbouring teeth.

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.

Factors affecting maxillary sinus pneumatization following posterior maxillary tooth extraction.

PURPOSE: The aims of the present study were 1) to quantitatively evaluate the extent of sinus pneumatization and 2) to determine the factors affecting sinus pneumatization. METHODS: Based on implant treatment records, a list of patients who underwent implant placement on the posterior maxilla was obtained. Among them, patients with pre-extraction and post-extraction (before implant placement) panoramic radiographs were selected. After excluding radiographs with low resolution and image distortion, the radiographs before and after extraction were superimposed using computer software. Subsequently, the extent of sinus pneumatization (the vertical change of the sinus floor) was measured. Simple and multiple mixed models were used to determine the factors affecting sinus pneumatization. RESULTS: A total of 145 patients were eligible for the present investigation. The average extent of sinus pneumatization was 1.56±3.93 mm at 176 tooth sites. Male sex, single tooth extraction, extraction of an endodontically compromised tooth, a class I root-sinus relationship, and sinus membrane thickening >10 mm favored pneumatization, but without statistical significance. The maxillary second molar presented the greatest pneumatization (2.25±4.39 mm) compared with other tooth types. This finding was confirmed in the multiple mixed model, which demonstrated a statistically significant impact of the extraction of a second molar compared with the extraction of a first premolar. CONCLUSIONS: Maxillary sinus pneumatization was 1.56±3.93 mm on average. The extraction of a second molar led to the greatest extent of pneumatization, which should be considered in the treatment plan for this tooth site.

Long-term effects of sinus membrane perforation on dental implants placed with transcrestal sinus floor elevation: A case-control study.

BACKGROUND: There is a little comparative data on implants placed transcrestally with/without sinus membrane (SM) perforation. PURPOSE: To compare the clinical and radiological outcomes of implants with maxillary sinus perforation and those without SM perforation. MATERIALS AND METHODS: Among 560 transcrestally placed implants in 324 patients, the patients who underwent cone-beam computed tomographic radiography (CBCT) were included. The following groups were established: implants with SM perforation (group P) and implants without SM perforation based on postoperative panoramic radiographs and patient records (group NP). Group NP was further divided into subgroups based on CBCT taken at the last patient visit: group NP1 consisting of implants with no protrusion or <1 mm of protrusion and group NP2 consisting of implants with ≥1 mm of protrusion. Mixed linear regression was performed for the factors affecting SM thickening and marginal bone loss. Mixed survival analysis was also performed. RESULTS: A total of 379 implants in 221 patients were eligible. The mean follow-up period was 112.03 ± 54.2 months. Twenty-six implants failed (2 and 24 implants in groups P and NP, respectively), mainly due to peri-implant bone loss. No statistically significant difference was noted between the groups in SM thickness (2.4 ± 2.8 mm, 2.1 ± 3.4 mm, and 2.5 ± 3.5 mm in groups P, NP1, and NP2, respectively, p > 0.05). Marginal bone loss in group NP1 was significantly greater than that in the other groups. In the mixed model, SM perforation was not a determinant of sinus membrane thickening and implant survival in the mixed models and the survival analysis, respectively. CONCLUSIONS: SM perforation in transcrestal sinus augmentation did not affect implant survival and SM thickening.

Implant survival and risk factor analysis in regenerated bone: results from a 5-year retrospective study.

PURPOSE: The aims of this study were to evaluate the 5-year cumulative survival rate (CSR) of implants placed with guided bone regeneration (GBR) compared to implants placed in native bone, and to identify factors contributing to implant failure in regenerated bone. METHODS: This retrospective cohort study included 240 patients who had implant placement either with a GBR procedure (regenerated bone group) or with pristine bone (native bone group). Data on demographic features (age, sex, smoking, and medical history), location of the implant, implant-specific features, and grafting procedures and materials were collected. The 5-year CSRs in both groups were estimated using Kaplan-Meier analysis. Risk factors for implant failure were analyzed with a Cox proportional hazards model. RESULTS: In total, 264 implants in the native bone group and 133 implants in the regenerated bone group were analyzed. The 5-year CSRs were 96.4% in the regenerated bone group and 97.5% in the native bone group, which was not a significant difference. The multivariable analysis confirmed that bone status was not an independent risk factor for implant failure. However, smoking significantly increased the failure rate (hazard ratio, 10.7; P=0.002). CONCLUSIONS: The 5-year CSR of implants placed in regenerated bone using GBR was comparable to that of implants placed in native bone. Smoking significantly increased the risk of implant failure in both groups.

Functional Endoscopic Sinus Surgery for Paranasal Sinusitis Originating From a Peri-implantitis-Triggered Infection in the Augmented Maxilla: A Case Report.

The aim of this case report was to report the course of treatment for advanced paranasal sinus infection triggered by peri-implantitis, managed using functional endoscopic sinus surgery (FESS), with outcomes. A nonsmoking male patient received sinus augmentation with implant placement on his left posterior maxilla 15 years ago. Possibly due to noncompliance to maintenance, peri-implantitis developed and progressed into the augmented bone area in the maxilla. Eventually, maxillary sinusitis occurred concomitantly with a spread of the infection to the other paranasal sinuses. Implant removal and intraoral debridement of inflammatory tissue were performed, but there was no resolution. Subsequently, FESS was performed, with removal of nasal polyp and sequestrum. After FESS, the patient's sinusitis resolved. Histologically, the sequestrum was composed of bone substitute particles, necrotic bone, stromal fibrosis, and a very limited cellular component. Two implants were placed on the present site, and no adverse event occurred for up to 1 year after the insertion of the final prosthesis. Peri-implantitis in the posterior maxilla can trigger maxillary sinusitis with concomitant infection to the neighboring paranasal sinuses. FESS should be considered to treat this condition.

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.

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.

Comparison of the Bone Harvesting Capacity of an Intraoral Bone Harvesting Device and Three Different Implant Drills.

The aim of the present study was to compare bone-collecting capacity of bone harvesting device and minimally irrigated low-speed drilling using three implant systems. One bone harvesting device and three commercially available drill systems were compared using the osteotomies on bovine rib bones. The amount of the collected bone particle and particle size (<500 µm: small, 500-1000 µm: medium, and >1000 µm: large) were measured. Total wet (1.535 ± 0.232 mL) and dry volume (1.147 ± 0.425 mL) of the bone particles from bone harvesting device were significantly greater than three drill systems (wet volume: 1.225 ± 0.187-1.27 ± 0.29 mL and dry volume: 0.688 ± 0.163-0.74 ± 0.311 mL) (P < 0.05). In all groups, the amount of large sized particles in wet and dry state was the greatest compared to that of medium and small particles. The dry weight of the bone particles showed the same tendency to volumetric measurement. In conclusion, total bone particles and large sized particles (>1000 µm) were harvested significantly greater by bone harvesting device than minimally irrigated low-speed drilling. The composition of particle size in all harvesting methods was similar to each other.

Primary implant stability in a bone model simulating clinical situations for the posterior maxilla: an in vitro study.

PURPOSE: The aim of this study was to determine the influence of anatomical conditions on primary stability in the models simulating posterior maxilla. METHODS: Polyurethane blocks were designed to simulate monocortical (M) and bicortical (B) conditions. Each condition had four subgroups measuring 3 mm (M3, B3), 5 mm (M5, B5), 8 mm (M8, B8), and 12 mm (M12, B12) in residual bone height (RBH). After implant placement, the implant stability quotient (ISQ), Periotest value (PTV), insertion torque (IT), and reverse torque (RT) were measured. Two-factor ANOVA (two cortical conditions×four RBHs) and additional analyses for simple main effects were performed. RESULTS: A significant interaction between cortical condition and RBH was demonstrated for all methods measuring stability with two-factor ANOVA. In the analyses for simple main effects, ISQ and PTV were statistically higher in the bicortical groups than the corresponding monocortical groups, respectively. In the monocortical group, ISQ and PTV showed a statistically significant rise with increasing RBH. Measurements of IT and RT showed a similar tendency, measuring highest in the M3 group, followed by the M8, the M5, and the M12 groups. In the bicortical group, all variables showed a similar tendency, with different degrees of rise and decline. The B8 group showed the highest values, followed by the B12, the B5, and the B3 groups. The highest coefficient was demonstrated between ISQ and PTV. CONCLUSIONS: Primary stability was enhanced by the presence of bicortex and increased RBH, which may be better demonstrated by ISQ and PTV than by IT and RT.

Prevalence of Porphyromonas gingivalis fimA genotypes in the peri-implant sulcus of Koreans assessed using a new primer.

PURPOSE: Porphyromonas gingivalis fimA is a virulence factor associated with periodontal diseases, but its role in the pathogenesis of peri-implantitis remains unclear. We aimed to evaluate the relationship between the condition of peri-implant tissue and the distribution of P. gingivalis fimA genotypes in Koreans using a new primer. METHODS: A total of 248 plaque samples were taken from the peri-implant sulci of 184 subjects. The control group consisted of sound implants with a peri-implant probing depth (PD) of 5 mm or less with no bleeding on probing (BOP). Test group I consisted of implants with a peri-implant PD of 5 mm or less and BOP, and test group II consisted of implants with a peri-implant PD of more than 5 mm and BOP. DNA was extracted from each sample and analyzed a using a polymerase chain reaction (PCR) with P. gingivalis-specific primers, followed by an additional PCR assay to differentiate the fimA genotypes in P. gingivalis-positive subjects. RESULTS: The Prevalence of P. gingivalis in each group did not significantly differ (P>0.05). The most predominant fimA genotype in all groups was type II. The prevalence of type Ib fimA was significantly greater in test group II than in the control group (P<0.05). CONCLUSIONS: The fimA type Ib genotype of P. gingivalis was found to play a critical role in the destruction of peri-implant tissue, suggesting that it may be a distinct risk factor for peri-implantitis.

Effects of a mouthwash containing potassium nitrate, sodium fluoride, and cetylpyridinium chloride on dentin hypersensitivity: a randomized, double-blind, placebo-controlled study.

PURPOSE: We evaluated the efficacy of a mouthwash containing potassium nitrate (KNO3) as its main component, along with sodium fluoride (NaF) and cetylpyridinium chloride (CPC). The primary endpoint was the relief of dentin hypersensitivity (DH) against the cold stimuli. The effects on other DH tests and periodontal inflammation were also evaluated. METHODS: We used a single-center, double-blind, placebo-controlled, randomized design. A total of 82 patients with DH (40 in the test group, 42 placebo controls) were analyzed using visual analog scales (VASs) for a cold test, a tactile test, a compressive air test, and self-reported pain during daily activities, as well as clinical parameters including plaque index, gingival index, modified sulcular bleeding index (mSBI), gingival recession, and probing depth, which were collected at baseline and after four and six weeks of mouthwash use. RESULTS: VAS scores for cold sensations, tactile sensations, the compressive air test, and self-reported pain significantly decreased from baseline during the six weeks in both groups (P<0.01), and no significant differences between the groups were found. In male patients (10 in the test group and 7 in the control group), both groups showed significant reductions in VAS scores for the cold test over the six weeks, and greater reductions were found in the test group than in the control group between four and six weeks (P=0.01) and between baseline and six weeks (P<0.01). In addition, the mSBI in the test group significantly decreased from baseline during the six weeks (P<0.01), and the changes at four and six weeks from baseline were significantly greater in the test group compared to the control group (P=0.03 and P=0.02, respectively). CONCLUSIONS: A mouthwash containing a mixture of KNO3, NaF, and CPC reduced DH and gingival inflammation, however, the efficacy was comparable to the control group.

Volumetric comparison of three different innovative bone collecting devices for autogenous bone grafts.

OBJECTIVE: The aim of this study was to evaluate the clinical relevance of three different bone collecting devices in a volumetric comparison. METHOD AND MATERIALS: Bone harvesting for the collection of bone particles was performed on bovine mandibles. Three different types of bone collecting devices (Tests 1, 2, and 3) were used. Ten drilling sites in each group were prepared and bone particles were collected. Bone particles were sieved twice in sieves with 500 µm and 1,000 µm openings. The bone particles were divided into three groups: < 500 µm (SP), 500-1,000 µm (MP), and >1,000 µm (LP). Total wet volume, fractional wet volume, fractional dry volume, and weight were measured. The shape of the dried particles was examined using a microscope. RESULTS: All particles in all three groups had a wood shaving-like appearance. With Test 1 and Test 2, LP were the most common (0.510 ± 0.064 mL, 0.430 ± 0.067 mL), and in Test 3, MP was the most common (0.112 ± 0.019 mL). Among the SP and MP, the wet volume of Test 3 was significantly greater than those of Tests 1 and 2 (P < .001). However, among the LP, the wet volume sequentially increased from Test 1, to Test 2, and Test 3 (P < .001). The proportion of dry volume was similar to that of wet volume. CONCLUSION: Three innovative bone collecting devices could collect comparable amounts of bone particles to commercially available bone graft materials.