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.

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.

A Novel Approach for the Treatment of Recurrent Oroantral Fistula Occurring at an Infected Sinus Augmentation Site.

Closing a recurrent oroantral fistula (OAF) that occurs at an infected sinus augmentation site is a challenge for clinicians. The recurrent OAF has a detrimental impact on bone regeneration and subsequent implant placement. This case report includes three cases in which sinus graft infection and OAF occurred after maxillary sinus augmentation (MSA). In these cases, treatments to control sinus infection were performed using an otolaryngologist; then, intraoral interventions comprising mucosal flap procedures, bone grafts, and barrier membrane applications were performed 2-5 times by oral surgeons. Nevertheless, OAF recurred persistently. The failure to stop OAF recurrence may be due to the inability to effectively block air pressure at the OAF site. Following a comprehensive debridement of the infected tissue at the previous sinus augmentation site, a pouch was created through sinus mucosal elevation. The perforated sinus mucosa at the OAF site was covered with a non-resorbable membrane in one case and with resorbable collagen membranes in the other two cases, followed by bone grafting within the pouch. Lastly, this procedure was completed by blocking the entrance of the pouch with a cortical bone shell graft and a resorbable collagen membrane. The cortical bone shell graft, obstructing the air pressure from the nasal cavity, facilitated bone formation, and, ultimately, allowed for implant placement. Within the limitations of the present case report, the application of a guided bone regeneration technique involving a cortical bone shell graft and a barrier membrane enabled the closure of the recurrent OAF and subsequent implant placement.

Impact of keratinized mucosa on implant-health related parameters: A 10-year prospective re-analysis study.

AIM: To investigate whether the lack of keratinized mucosa (KM) affects peri-implant health after 10 years of loading. MATERIALS AND METHODS: Data from 74 patients with 148 implants from two randomized controlled studies comparing different implant systems were included and analyzed. Clinical parameters including bleeding on probing (BOP), probing depth (PD), plaque index, marginal bone loss (MBL), and KM width (KMW) at buccal sites were collected at baseline (time of the final prosthesis insertion), 5-year and 10 years postloading. Multivariable logistic and linear regression models by means of a generalized estimated equation (GEE) were used to evaluate the influence of buccal KM on peri-implant clinical parameters; BOP, MBL, PD, and adjusted for implant type (one-piece or two-piece) and compliance. RESULTS: A total of 35 (24.8%) implants were healthy, 67 (47.5%) had mucositis and 39 (27.6%) were affected by peri-implantitis. In absence of buccal KM (KM = 0 mm), 75% of the implants exhibited mucositis, while in the presence of KM (KMW >0 mm) 41.2% exhibited mucositis. Regarding peri-implantitis, the corresponding percentages were 20% (KM = 0 mm) and 26.7% (KM >0 mm). Unadjusted logistic regression showed that the presence of buccal KM tended to reduce the odds of showing BOP at buccal sites (OR: 0.28 [95% CI, 0.07 to 1.09], p = 0.06). The adjusted logistic regression model revealed that having buccal KM (OR: 0.21 [95% CI, 0.05 to 0.85], p = 0.02) and using two-piece implants (OR: 0.34 [95% CI, 0.15 to 0.75], p = 0.008) significantly reduced the odds of showing BOP. Adjusted linear regression by means of GEE showed that KM and two-piece implants were associated with reduced MBL and MBL changes (p < 0.05). CONCLUSION: The lack of buccal KM appears to be linked with peri-implant parameters such as BOP and MBL, but the association is weak. The design of one-piece implants may account for their increased odds of exhibiting BOP.

Augmentation of keratinized tissue using autogenous soft-tissue grafts and collagen-based soft-tissue substitutes at teeth and dental implants: Histological findings in a pilot pre-clinical study.

AIM: To histomorphometrically assess three treatment modalities for gaining keratinized tissue (KT) at teeth and at dental implants. MATERIALS AND METHODS: In five dogs, the distal roots of the mandibular second, third and fourth premolars were extracted. Dental implants were placed at the distal root areas 2 months later. After another 2 months, KT augmentation was performed at both distal (implants) and at mesial root (teeth) areas in the presence (wKT groups) or absence (w/oKT groups) of a KT band at the mucosal/gingival level. Three treatment modalities were applied randomly: apically positioned flap only (APF), free gingival grafts (FGGs) and xenogeneic collagen matrices (XCMs). A combination of the above produced six groups. Two months later, tissue sections were harvested and analysed histomorphometrically. RESULTS: The median KT height and length were greatest at implants with FGG in both wKT (3.7 and 5.1 mm, respectively) and w/oKT groups (3.7 and 4.6 mm), and at teeth with FGG in wKT groups (3.7 and 6.1 mm) and with APF in the w/oKT groups (3.9 and 4.4 mm). The XCM and APF produced more favourable results at teeth than at implants. CONCLUSIONS: FGG was advantageous in gaining KT, especially at implants.

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.

Submerged Technique of Partially De-Epithelialized Free Gingival Grafts for Gingival Phenotype Modification in the Maxillary Anterior Region: A Case Report of a 34-Year Follow-up.

A coronally advanced flap combined with a subepithelial connective tissue graft is considered the gold standard for achieving root coverage on exposed root surfaces. Nevertheless, challenges arise when this technique is applied to multiple teeth and when the palatal soft tissue is very thin. Several surgical modifications have been reported to simultaneously achieve both single or multiple root coverage and widening of the keratinized gingiva. In this context, there have been no reported cases utilizing the submerged technique with partially de-epithelialized free gingival grafts. We intend to introduce a submerged technique involving partially de-epithelialized free gingival grafts for the modification of soft tissue phenotypes in the maxillary anterior region.

Lateral Peri-Implantitis: Successful Management via Guided Bone Regeneration at Mandibular First Molar Implant.

Infections occurring around implants are divided into marginal peri-implantitis and retrograde peri-implantitis (RPI). Marginal peri-implantitis starts in the crestal bone and progresses to the apical portion, and RPI starts in the apical bone and progresses to the coronal portion. However, lateral peri-implantitis (LPI) occurring on the side of the implant body has not yet been reported, and the cause is unclear. This 63-year-old male patient is a case of unusual bone resorption that occurred in the lateral portion of the implant body 26 months after lateral bone augmentation. The origin of LPI was an infection at the site of laterally augmented bone. Rather than implant removal, this report demonstrates an alternative treatment option of guided bone regeneration after the enucleation and detoxification of the implant surface with successful clinical and radiographic results for 2 years.

Management of Posterior Mandibular Bone Cavitation for Dental Implant Placement: A Case Series of 5-24 Years of Follow-Up.

Focal osteo-cavitation in the posterior mandible is a condition that clinicians do not know well. Inadvertent implant placement in such areas may result in nerve damage due to abrupt drill penetration and implant displacement in the medullary space. In the present case series, focal osteo-cavitation was managed with the following procedures: (1) undersized drilling, (2) gentle trabecular curettage, (3) bone substitute material grafting in the cavity, and (4) long healing period for osseointegration. In all cases, a sudden loss of drilling pressure immediately after passing through the thin cortical layer revealed focal osteo-cavitation. Following undersized drilling and gentle trabecular curettage, the bone substitute material was packed into the cavity with care not to press the inferior alveolar canal. Implant placement was subsequently performed. Despite a lack of primary implant stability in 3 of 4 cases, all implants were successfully osseointegrated after 6-9 months. Over 5-24 years, all implants functioned well.

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.

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.

Vertical bone augmentation using collagenated or non-collagenated bone substitute materials with or without recombinant human bone morphogenetic protein-2 in a rabbit calvarial model.

PURPOSE: The aim of this study was to determine 1) the bone-regenerative effect of porcine bone block materials with or without collagen matrix incorporation, 2) the effect of a collagen barrier, and 3) the effect of adding recombinant human bone morphogenetic protein-2 (rhBMP-2) to the experimental groups. METHODS: Four treatment modalities were applied to rabbit calvaria: 1) deproteinized bovine bone mineral blocks (DBBM), 2) porcine bone blocks with collagen matrix incorporation (PBC), 3) porcine bone blocks alone without collagen matrix incorporation (PB), and 4) PBC blocks covered by a collagen membrane (PBC+M). The experiments were repeated with the addition of rhBMP-2. The animals were sacrificed after either 2 or 12 weeks of healing. Micro-computed tomography (micro-CT), histologic, and histomorphometric analyses were performed. RESULTS: Micro-CT indicated adequate volume stability in all block materials. Histologically, the addition of rhBMP-2 increased the amount of newly formed bone (NB) in all the blocks. At 2 weeks, minimal differences were noted among the NB of groups with or without rhBMP-2. At 12 weeks, the PBC+M group with rhBMP-2 presented the greatest NB (P<0.05 vs. the DBBM group with rhBMP-2), and the PBC and PB groups had greater NB than the DBBM group (P>0.05 without rhBMP-2, P<0.05 with rhBMP-2). CONCLUSIONS: The addition of rhBMP-2 enhanced NB formation in vertical augmentation using bone blocks, and a collagen barrier may augment the effect of rhBMP-2.

Successful Management of Late Sinus Graft Infection via Functional Endoscopic Sinus Surgery and Press-Fit Block Bone Graft: A Case Report.

The purpose of this case report is to feature an interesting case where a staged approach was used to manage a failed implant site that led to a late sinus graft infection and sinusitis with an oroantral fistula (OAF), by using functional endoscopic sinus surgery (FESS) and an intraoral press-fit block bone graft technique. Sixteen years ago, a 60-year-old female patient underwent maxillary sinus augmentation (MSA) with 3 implants placed simultaneously in the right atrophic ridge. However, No. 3 and 4 implants were removed due to advanced peri-implantitis. The patient later developed purulent discharge from the site, headache, and complained of air leakage due to an OAF. The patient was referred to an otolaryngologist for FESS to treat the sinusitis. Two months after FESS, the sinus was re-entered. Residual inflammatory tissues and necrotic graft particles in the OAF site were removed. A block bone harvested from the maxillary tuberosity was press-fitted to the OAF site and grafted. After 4 months of grafting, the grafted bone was well incorporated with the surrounding native bone. Two implants were successfully placed in the grafted site with good initial stability. The prosthesis was delivered 6 months after implant placement. After the 2 years of follow-up, patient was functioning well without sinus complications. Within limitation of this case report, the staged approach via FESS and intraoral press-fit block bone graft is an effective method that can be used to successfully manage OAF and vertical defects at the implant site.

Bone Regenerative Potential of Cross-Linked Collagen Membrane in Peri-Implant Osseous Defect: Case Series with Histologic/Micro-Computed Tomographic Findings.

The role of a barrier membrane is crucial in guided bone regeneration (GBR) for space creation and cell occlusiveness. Those properties of the membrane should be sustained for a sufficient period. For such purpose, several cross-linked collagen membranes were introduced and demonstrated favorable clinical outcomes. However, histologic data were not sufficient to support the effect of cross-linked collagen membranes. In the present case series, healing after GBR using a cross-linked collagen membrane was investigated in-depth via histologic and micro-computed tomographic (micro-CT) analyses. 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide cross-linked collagen membrane was used in GBR for treating various peri-implant bone defects in seven patients. After 4-7 months of healing, newly formed tissue of hard consistency was observed over the implant platform. This tissue was carefully harvested and assessed. In micro-CT and histological analyses, evident new bone formation was revealed, especially in the vicinity of the collagen membrane. Moreover, it was histologically found that some newly formed bone was in intimate contact with the membrane. Although the exact mechanism of bone regeneration in the present cases was not clearly elucidated, the cross-linked collagen membrane appeared to contribute to ossification in GBR. Further studies are needed to confirm the findings of the present case series.

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).

Changes in sinus mucosal thickening in the course of tooth extraction and lateral sinus augmentation with surgical drainage: A cone-beam computed tomographic study.

OBJECTIVES: The objective of the study was to evaluate the radiographic changes in sinus mucosal thickness (SMT) in patients with mucosal thickening of odontogenic origin after maxillary molar extraction and lateral sinus augmentation with simultaneous surgical drainage and implant placement. MATERIALS AND METHODS: Forty-six patients were included in this study. The changes in SMT were evaluated using cone-beam computed tomography images produced at four time points: before extraction (T0), before surgery (T1), immediately after surgery (T2), and after prosthesis delivery (T3), and statistical differences between time points were analyzed. The changes in SMT and augmented bone height (ABH) regarding the reason of extraction, smoking, ostial patency, and the presence of postoperative sinusitis were also evaluated. RESULTS: Over time points, SMT gradually decreased (T0: 19.44 ± 9.22 mm, T1: 15.10 ± 8.89 mm, T2: 8.42 ± 6.01 mm, and T3: 4.16 ± 4.91 mm) (p < .05). Five out of 6 patients with ostial obstruction at T1 presented ostial patency at T3. Two patients developed postoperative sinusitis but recovered with medication. Ostial patency at T1, SMT at T1, and reason of extraction did not statistically significantly influence SMT at T3. SMT at T1 had no statistically significant impact on ABH change between T2 and T3. CONCLUSION: Sinus mucosal thickness was gradually reduced by extraction of compromised teeth and drainage during lateral sinus augmentation. The drainage contributed more to the reduction in SMT.

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.

Endodontic sealer-induced maxillary sinusitis: intraoral surgical approach and implant placement at a site of failed nasal endoscopic surgeries.

A 28-year-old male patient was referred from an otorhinolaryngologist for managing unilateral chronic maxillary sinusitis (MS). The patient had undergone two functional endoscopic sinus surgeries (FESS), although the MS was not resolved. Based on his dental history, endodontic treatment had been done on the symptomatic area. A leak of endodontic sealer and peri-apical lesion on tooth #14 was found on cone-beam computed tomographic examination. Extraction of tooth #14 and the modified Caldwell-Luc operation were performed to remove the endodontic sealer material and relevant inflammatory tissue. The sinus membrane lining was maintained as much as possible during the surgery. Implant placement was performed on the tooth extraction site. All clinical symptoms disappeared after the surgery. Radiographic and endoscopic examination revealed successful osseointegration of the implant and complete resolution of the MS. FESS alone may not be sufficient to treat MS derived from dental origin. For unilateral MS, dental history should be carefully checked.

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.

Effect of the size of the bony access window and the collagen barrier over the window in sinus floor elevation: a preclinical investigation in a rabbit sinus model.

PURPOSE: The aim of this study was to investigate the effect of (1) the size of the bony access window and (2) collagen membrane coverage over the window in sinus floor elevation in a rabbit sinus model. METHODS: Small bony access windows (SW; ø 2.8 mm) were made in 6 rabbits and large windows (LW; ø 6 mm) in 6 other rabbits. Both sinuses in each rabbit were allocated to groups with or without coverage of a collagen membrane (CM) on the window, resulting in 4 groups: SW, LW, SW+CM, and LW+CM. After 4 weeks of healing, micro-computed tomographic, histologic, and histomorphometric analyses were performed. RESULTS: Bony healing in the window area was incomplete in all groups, but most bone graft particles were well confined in the augmented cavity. Histologically, the pattern of new bone formation was similar in all groups. Histomorphometrically, the percentage of newly formed bone was greater in the groups with CM than in the groups without CM, and in the groups with SW than in the groups with LW (12.92%±6.40% in the SW+CM group, 4.21%±7.73% in the SW group, 10.45%±4.81% in the LW+CM group, 11.77%±3.83% in the LW group). The above differences were not statistically significant (P>0.05). CONCLUSIONS: The combination of a small bony access window and the use of a collagen membrane over the window favored new bone formation compared to other groups, but this result should be further investigated due to the limitations of the present animal model.