Clinical and radiographic peri-implant tissue changes for implants restored with convex or concave abutment shapes: A 3-year randomized controlled trial.

OBJECTIVES: The aim was to evaluate peri-implant tissue levels over a 3-year period for implants connected to either convex or concave final abutments at the time of implant placement. MATERIALS AND METHODS: In this randomized, double-masked, controlled clinical study, 28 patients with one missing maxillary premolar were assigned to receive one single implant with a permanent abutment of either convex (CONVEX Group) or concave (CONCAVE Group) emergence shape at the time of implant placement. Clinical and radiographic data were collected at the time of implant placement (IP), final prosthesis delivery (PR), 12 months (FU-1), and 36 months (FU-3) following implant placement. RESULTS: At the FU-3 13 patients were available from the CONCAVE Group (n = 13) and eleven from the CONVEX Group (n = 11). The mean change in buccal peri-implant mucosa position (MP) from IP to FU-3 was -0.54 ± 0.93 mm for the CONVEX Group and - 0.53 ± 0.87 mm for CONCAVE Group (p = .98). The amount of bone remodeling above the implant platform from IP to FU-3 was -0.69 ± 0.48 mm for the CONVEX Group and -0.16 ± 0.22 mm for the CONCAVE Group (p = .005). CONCLUSION: The study failed to support the hypothesis that abutment macro-design has an effect on buccal peri-implant mucosa margin position over time.

Implant-abutment connection as contributing factor to peri-implant diseases.

Dental implant-supported prostheses are an established treatment modality for the functional and esthetic rehabilitation of partial and/or complete edentulous patients. One of the most essential factors for successful treatment outcomes stems from preservation of the peri-implant bone. Early peri-implant crestal bone loss has been a common observation, coincides with the time period where most treatment manipulations occur and has been considered as a complex multifactorial event. Microbial leakage at the implant-abutment interface has been associated with inflammatory reactions that may jeopardize peri-implant crestal bone stability. Prevention of microbial leakage at the implant-abutment interface is a major challenge in the construction of two-piece implant systems. Changes in the implant-abutment complex design achieved reduction in the magnitude of microbial leakage and/or separation of the implant-abutment interface from the osseous surface. However, it is still unclear if microbial leakage at the implant-abutment interface plays a role beyond the initial crestal bone remodeling, namely on the development of peri-implantitis. Therefore, the aim of this review is to analyze the knowledge available on the integrity of different types of implant-abutment connections and their potential role on the development of peri-implant crestal bone loss and peri-implant diseases.

The influence of abutment macro-design on clinical and radiographic peri-implant tissue changes for guided, placed, and restored implants: A 1-year randomized controlled trial.

OBJECTIVES: The aim was to evaluate the peri-implant tissue levels over a 1-year period for implants connected to either convex or concave final abutments at the time of implant placement. MATERIALS AND METHODS: In this randomized, double masked, controlled clinical study, twenty-eight patients with one missing maxillary premolar were allocated to receive one single implant with abutment of either convex (CX Group) or concave (CV Group) emergence shape. A block randomization sequence was used to allocate treatments. Opaque sealed randomization envelopes were used for allocation concealment. All implants received final abutments and interim crowns at implant placement and permanent crowns following 3 months. Clinical and radiographic data were collected at the time of implant placement (IP), final prosthesis delivery (PR), and 12 months following implant placement (FU-1). RESULTS: One patient from the CX Group (n = 13) dropped out from the study and for one patient from CV Group (n = 13), the implant failed to integrate. The mean change in peri-implant buccal mucosa position (MP) from IP to FU-1 was -0.76 ± 0.72 mm for CX Group and -0.69 ± 0.89 mm for CV Group (p = 0.8). The amount of bone remodeling above the implant platform from IP to FU-1 was -0.66 ± 0.46 mm for the CX Group and -0.24 ± 0.25 mm for the CV Group (p = 0.007). Buccal bone thickness was significantly correlated with the amount of buccal MP change from IP to FU-1 (r = 0.4, p = 0.038). CONCLUSION: The study failed to support the hypothesis that abutment macro-design has an effect on peri-implant mucosa margin position changes over time.

Alveolar Ridge Expansion by Osseodensification-Mediated Plastic Deformation and Compaction Autografting: A Multicenter Retrospective Study.

INTRODUCTION: Osseodensification preserves bone bulk, facilitates compaction autografting, and deforms trabecular bone in an outward strain, which result in alveolar ridge plastic expansion. The aim of this retrospective study was to evaluate ridge expansion after osseodensification. MATERIALS AND METHODS: Patients treated with implant placement through osseodensification were evaluated. The alveolar ridge width was measured at the level of the crest and 10 mm apical to the crest before and after osseodensification. Insertion torque and implant stability quotient (ISQ) values were recorded at implant placements. Expansion values were grouped into the following 3 groups according to the initial alveolar ridge width: group 1: 3 to 4 mm (n = 9), group 2: 5 to 6 mm (n = 12), and group 3: 7 to 8 mm (n = 7). RESULTS: Twenty-one patients who received 28 implants were included. Twenty-six implants were integrated, resulting in a survival rate of 92.8%. There was a significant difference in the mean expansion value at the coronal aspect of the ridge between group 1, group 2, and group 3 (2.83 ± 0.66 mm, 1.5 ± 0.97 mm, 1.14 ± 0.89 mm, P < 0.05). The mean torque and ISQ values were 61.2 ± 13.9 Ncm and 77 ± 3.74. CONCLUSION: Osseodensification can alter ridge dimensions and allow for ridge expansion. Greater expansion can be expected at the crest in narrow ridges with adequate trabecular bone volume.

Porphyromonas gingivalis-nucleoside-diphosphate-kinase inhibits ATP-induced reactive-oxygen-species via P2X7 receptor/NADPH-oxidase signalling and contributes to persistence.

Ligation of P2X7 receptors with a 'danger signal', extracellular ATP (eATP), has recently been shown to result in production of intracellular reactive-oxygen-species (ROS) in macrophages. We show that primary gingival epithelial cells (GECs) produce sustained, robust cellular ROS upon stimulation by eATP. The induction of ROS was mediated by P2X7 receptor signalling coupled with NADPH-oxidase activation, as determined by pharmacological inhibition and RNA interference. Furthermore, Porphyromonas gingivalis, an oral opportunistic pathogen, upregulated the antioxidant glutathione response, modulated eATP-induced cytosolic and mitochondrial ROS generated through P2X7 /NADPH-oxidase interactome, and subsequently blocked oxidative stress in GECs via temporal secretion of a P. gingivalis effector, nucleoside-diphosphate-kinase (Ndk). An ndk-deficient P. gingivalis mutant lacked the ability to inhibit ROS production and persist intracellularly following eATP stimulation. Treatment with recombinant Ndk significantly diminished eATP-evoked ROS production. P. gingivalis infection elicited a strong, time-dependent increase in anti-oxidativemitochondrial UCP2 levels, whereas ndk-deficient mutant did not cause any change. The results reveal a novel signalling cascade that is tightly coupled with eATP signalling and ROS regulation. Ndk by P. gingivalis counteracts these antimicrobial signalling activities by secreting Ndk, thus contributing to successful persistence of the pathogen.

The effect of dynamic loading on bacterial colonization of the dental implant fixture-abutment interface: an in vitro study.

Bacterial colonization of the fixture-abutment interface (FAI) microgap may contribute to increased marginal bone loss. The contribution of loading on bacterial colonization has not been thoroughly evaluated with in vitro experiments. The aim of this study was to evaluate the effect of dynamic loading on the colonization of oral microorganisms in the FAI microgap of dental implants with internal Morse-taper connection. Forty implants were divided into two groups (n = 20/group) based on subjection to dynamic loading conditions. Both Group 1 and 2 were comprised of fixtures that connected to standard abutments and allowed to incubate in a bacterial solution of Escherichia coli . The specimens of Group 2 were loaded with 500 000 cycles of 50 N using a chewing simulator. Following disconnection of fixtures and abutments, microbial samples were taken from the threaded portion of the abutment, plated and cultured under appropriate conditions. One of the 20 implants of Group 1 and 4 of the 20 implants of Group 2 had FAI microgaps colonized by E coli . With the limits of this study, it indicates that implants with internal Morse-taper connection exhibited minimal bacterial penetration down to the threaded part of the FAI and that dynamic loading increases the potential for such bacterial penetration.

The Effect of Osteotomy Preparation Technique and Implant Diameter on Primary Stability and Bone-implant Interface of Short Implants (6 mm).

PURPOSE: To evaluate the effect of osteotomy preparation technique and implant diameter on primary stability and bone-implant interface of short implants (6mm), when placed in bone with high degree of cancellous content. MATERIAL AND METHOD: 90 short (S) implants (6 mm) divided in nine groups based on width (Narrow 4.2 mm, Regular 4.8 mm, Wide 5.4 mm) (N,R,W) and osteotomy preparation (Standard, Osteotome, Osseodensification) (ST, OT, OD) and placed in porcine tibia plateau bone samples: Group SN-ST; Group SN-OT; Group SN-OD; Group SRST; Group SR-OT; Group SR-OD; Group SW-ST; Group SW-OT and Group SW-OD. Insertion torque and Implant Stability Quotient (ISQ) were measured. Four implants from each group SNST, SN-OT, SN-OD were evaluated histomorphometrically. RESULTS: Insertion torque was significantly higher for implants of Group SW-OD compared to Group SW-ST (50.00 ±14.14 Ncm vs 28.00 ±10.85 Ncm, p= 0.005) and Group SW-OT compared to Group SW-ST (46.87 ±17.10 Ncm vs 28.00 ±10.85 Ncm, p=0.026). Insertion torque was significantly higher for implants of Group SW-OD compared to Group SN-OD (50.00 ±14.14 Ncm vs 31.5 ±15.82 Ncm, p=0.04). No significant differences were observed for the percentage of bone, marrow space and connective tissue in contact to the implant surface between studied groups. CONCLUSION: Osteotomy preparation technique at sites with high degree of cancellous content can influence the implant insertion torque for short and wide implants (5.4x6mm). Implant width can influence the insertion torque of short implants placed with the osseodensification technique.

Impact of surface chemical treatment in surgical regenerative treatment of ligature-induced peri-implantitis: A canine study.

BACKGROUND: Implant surface decontamination is a critical step in peri-implantitis treatment. The aim of this study was to assess the effect chemotherapeutic agents have on reosseointegration after treatment on ligature-inducted peri-implantitis. METHODS: Six male canines had 36 implants placed and ligatures were placed around them for 28 weeks to establish peri-implantitis. The peri-implant defects were randomly treated by 1 of 3 methods: 0.12% chlorhexidine (CHX test group), 1.5% sodium hypochlorite (NaOCl test group), or saline (Control group). Sites treated with NaOCl and CHX were grafted with autogenous bone, and all sites then either received a collagen membrane or not. Histology sections were obtained at 6 months postsurgery to assess percentage of reosseointegration. RESULTS: Thirty-five implants were analyzed (CHX: 13; NaOCl: 14; Control:8). NaOCl-treated sites demonstrated reosseointegration with direct bone-to-implant-contact on the previously contaminated surfaces (42% mean reosseointegration), which was significantly higher than Controls (p < 0.05). Correspondingly, clinical improvement was noted with a significant reduction in probing depth from 5.50 ± 1.24 mm at baseline to 4.46 ± 1.70 mm at 6-months postsurgery (p = 0.006). CHX-treated sites demonstrated a nonsignificant reosseointegration of 26% (p > 0.05); however, in the majority of cases, the new bone growth was at a distance from the implant surface without contact. Probing depths did not improve in the CHX group. The use of membrane did not influence reosseointegration or probing depths (all p > 0.05). CONCLUSION: Titanium implants with peri-implantitis have the capacity to reosseointegrate following regenerative surgery. However, treatment response is contingent upon the chemotherapeutic agent selection. Additional chemical treatment with 1.5% NaOCl lead to the most favorable results in terms of changes in defect depth and percentage of reosseointegration as compared to CHX, which may hinder reosseointegration.

The role of hyperglycemia in mechanisms of exacerbated inflammatory responses within the oral cavity.

Immune modulating factors are necessary for pathogen clearance, but also contribute to host tissues damage, as those seen in periodontal diseases. Many of these responses can be exacerbated by host conditions including type 2 diabetes [T2D], where toll-like receptor 4 [TLR4] and the receptor for advanced glycated end products [RAGE] play a significant role. Here we investigate causality associated with the increase in inflammatory markers observed in periodontally diseased patients with T2D using multi-variant correlation analysis. Inflammation associated with periodontal diseases, characterized by elevated pro-inflammatory cytokines, innate immune receptor expression, and cellular infiltrate was exacerbated in patients with T2D. In addition, a feed forward loop regulated by poor glycemic control was associated with a loss of mucosal barrier integrity and accumulation of innate immune receptor ligands resulting in an exacerbation of ongoing inflammation, where RAGE and TLR4 cooperated to induce responses in oral epithelial cells, which were exacerbated by hyperglycemia.

ATP-dependent activation of an inflammasome in primary gingival epithelial cells infected by Porphyromonas gingivalis.

Production of IL-1beta typically requires two-separate signals. The first signal, from a pathogen-associated molecular pattern, promotes intracellular production of immature cytokine. The second signal, derived from a danger signal such as extracellular ATP, results in assembly of an inflammasome, activation of caspase-1 and secretion of mature cytokine. The inflammasome component, Nalp3, plays a non-redundant role in caspase-1 activation in response to ATP binding to P2X(7) in macrophages. Gingival epithelial cells (GECs) are an important component of the innate-immune response to periodontal bacteria. We had shown that GECs express a functional P2X(7) receptor, but the ability of GECs to secrete IL-1beta during infection remained unknown. We find that GECs express a functional Nalp3 inflammasome. Treatment of GECs with LPS or infection with the periodontal pathogen, Porphyromonas gingivalis, induced expression of the il-1beta gene and intracellular accumulation of IL-1beta protein. However, IL-1beta was not secreted unless LPS-treated or infected cells were subsequently stimulated with ATP. Conversely, caspase-1 is activated in GECs following ATP treatment but not P. gingivalis infection. Furthermore, depletion of Nalp3 by siRNA abrogated the ability of ATP to induce IL-1beta secretion in infected cells. The Nalp3 inflammasome is therefore likely to be an important mediator of the inflammatory response in gingival epithelium.

Comparative soft and hard tissue responses to titanium and polymer healing abutments.

Limited information exists regarding soft tissue and hard tissue responses to abutments with different material composition. The aim of this study is to evaluate soft and hard tissue responses to titanium and polymer healing abutments over a 3-month period. Sixteen patients were included in this prospective trial. Implants were provisionalized with either titanium or polymer healing abutments. Changes of marginal bone level and soft tissue dimensions were recorded at implant installation and at 3 months.

The Influence of Abutment Macrodesign on Facial Peri-implant Tissue Dimensions for Guided Placed and Restored Implants at Healed Sites: 1-Year CBCT Findings from a Randomized Controlled Clinical Trial.

This study aimed to evaluate facial peri-implant tissue dimensions for implants connected to either convex or concave final abutments. Patients (n = 28) were randomly allocated to receive a single implant with an abutment of either convex (Group CX) or concave (Group CV) emergence shape. Twelve months after implant placement, CBCT scans were taken and reference points were identified: first visible bone-to-implant contact, implant shoulder (IS), bone crest (BC), and marginal mucosal level (MML). Mucosal thickness was evaluated at the level of IS (MT1), above the level of BC (MT2), and at the mid-distance of BC-MML (MT3). The mean total vertical peri-implant mucosa height was 3.26 ± 0.77 mm for Group CX and 3.70 ± 0.99 mm for Group CV (P = .23). The mean vertical peri-implant mucosa height below the bone crest was 0.62 ± 0.57 mm for Group CX and 1.26 ± 0.95 mm for Group CV (P = .04). Group CV had greater mean MT2 (4.09 ± 0.72 mm vs 3.36 ± 0.81 mm; P = .02) and MT3 (2.81 ± 0.66 mm vs 2.03 ± 0.60 mm; P = .005) compared to Group CX. Abutment macrodesign may have an effect on vertical and horizontal peri-implant tissue dimensions.

Autoreactivity of serum immunoglobulin to periodontal tissue components: a pilot study.

BACKGROUND: Periodontal diseases are inflammatory diseases resulting in the destruction of tissues of the periodontium. Although bacteria must be present for periodontal disease to occur, a susceptible host is also required, which is determined by genetic, environmental, and acquired factors. One such factor, autoimmunity, may play a role in the tissue destruction. Data indicate that some antibodies that occur in the gingival lesion are directed to host tissue components, such as type I collagen, although investigations of other periodontal autoimmune targets are limited. METHODS: Histologic sections and extracts from periodontally healthy teeth and the associated soft tissues were probed with serum from localized aggressive periodontitis (LAgP), chronic periodontitis (CP), and periodontally healthy subjects to determine autoreactivity to components of the periodontium. Any autoreactivity observed was characterized further by mass spectrometry and enzyme-linked immunosorbent assay. RESULTS: Autoreactivity to components of the periodontium was observed in CP and LAgP. Known autoimmune targets, such as collagen and heat shock protein, were identified along with multiple potential autoimmune targets, including members of the extracellular matrix, such as vimentin, spectrin, filamin, actin, lamin, keratin, and tubulin. Finally, it was determined that the autoreactivity observed in LAgP was more severe and diverse than that observed in CP. CONCLUSION: These data demonstrated that autoimmune reactivity can play a role in the tissue destruction of periodontal disease but that the nature of the autoreactivity may differ based on the type and/or stage of periodontal disease.

Locally delivered doxycycline as an adjunct to mechanical debridement at retreatment of periodontal pockets.

BACKGROUND: The aim of this study was to evaluate if adjunctive, locally delivered controlled-release doxycycline might improve the outcome of reinstrumentation of pathologic pockets persisting after initial periodontal therapy. METHODS: Subjects with chronic periodontitis underwent initial treatment including full-mouth ultrasonic debridement and oral hygiene instructions. At the 3-month reexamination, 32 subjects with remaining pathologic sites were assigned randomly to one of two retreatment protocols: ultrasonic instrumentation alone (control) or ultrasonic instrumentation plus application of an 8.8% doxycycline gel (test). Clinical examinations of plaque, probing depth (PD), relative attachment level (RAL), and bleeding on probing were performed before retreatment (baseline) and after 3 and 9 months. Primary efficacy variables were the percentage of closed pockets, i.e., PD < or =4 mm, and changes in PD and RAL. RESULTS: Baseline examination revealed no significant difference in mean PD between treatment groups. The mean PD reduction at 3 months was 0.9 mm (95% confidence interval [CI]: 0.6 to 1.2) in the control group and 1.0 mm (95% CI: 0.7 to 1.3) in the test group (P >0.05). At 9 months, both treatment groups showed a mean PD reduction of 1.1 mm. The mean RAL gain was 0.6 mm at 3 months and approximately 0.8 at 9 months for both groups. The probability of pocket closure was not improved by the adjunctive antibiotic therapy. Only factors at the tooth site level (plaque presence, furcation involvement, and presence of an intrabony defect) were identified by multilevel analysis as significant for the treatment outcome. CONCLUSION: Locally delivered doxycycline failed to improve the healing outcome of reinstrumentation of periodontal pockets showing a poor initial response to pocket/root debridement.

Abutment Disconnection/Reconnection Affects Peri-implant Marginal Bone Levels: A Meta-Analysis.

PURPOSE: Preclinical and clinical studies have shown that marginal bone loss can be secondary to repeated disconnection and reconnection of abutments that affect the peri-implant mucosal seal. The aim of this systematic review and meta-analysis was to evaluate the impact of abutment disconnections/reconnections on peri-implant marginal bone level changes. MATERIALS AND METHODS: To address this question, two reviewers independently performed an electronic search of three major databases up to October 2015 complemented by manual searches. Eligible articles were selected on the basis of prespecified inclusion and exclusion criteria after a two-phase search strategy and assessed for risk of bias. A random-effects meta-analysis was performed for marginal bone loss. RESULTS: The authors initially identified 392 titles and abstracts. After evaluation, seven controlled clinical studies were included. Qualitative assessment of the articles revealed a trend toward protective marginal bone level preservation for implants with final abutment placement (FAP) at the time of implant placement compared with implants for which there were multiple abutment placements (MAP). The FAP group exhibited a marginal bone level change ranging from 0.08 to 0.34 mm, whereas the MAP group exhibited a marginal bone level change ranging from 0.09 to 0.55 mm. Meta-analysis of the seven studies reporting on 396 implants showed significantly greater bone loss in cases of multiple abutment disconnections/reconnections. The weighted mean difference in marginal bone loss was 0.19 mm (95% confidence interval, 0.06-0.32 mm), favoring bone preservation in the FAP group. CONCLUSION: Within the limitations of this meta-analysis, abutment disconnection and reconnection significantly affected peri-implant marginal bone levels. These findings pave the way for revisiting current restorative protocols at the restorative treatment planning stage to prevent incipient marginal bone loss.

A Novel Rat Model of Polymicrobial Peri-Implantitis: A Preliminary Study.

BACKGROUND: Peri-implantitis is a complex polymicrobial biofilm-induced inflammatory osteolytic gingival infection that results in orofacial implant failures. To the best knowledge of the authors, there are no preclinical in vivo studies in implant dentistry that have investigated the inflammatory response to known microbial biofilms observed in humans. The aim of this study is to develop a novel peri-implant rat model using an established model of polymicrobial periodontitis. METHODS: Wistar rats were used for the study of experimental peri-implantitis. One month after extraction of maxillary first molars, a titanium mini-implant was inserted. Two months after implant healing, implants were uncovered, and abutment fixing was done using cyanoacrylate to prevent abutment loosening. Rats were separated into two groups (group A: polymicrobial-infected and group B: sham-infected). One week after healing of abutments, rats were infected with Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia for 12 weeks. Bacterial colonization, bone resorption, and implant inflammation were evaluated by polymerase chain reaction (PCR), microcomputed tomography, and histology, respectively. RESULTS: Three rats with four implants in the infection group and two rats with three implants in the sham-infection group were analyzed. PCR analysis revealed presence of bacterial genomic DNA, and infection elicited significant immunoglobulin (Ig)G and IgM antibody responses, indicating bacterial colonization/infection around implants. Infection induced an enhanced mean distance from implant platform to the first bone-to-implant contact, extensive peri-implantitis with advanced bone resorption, and extensive inflammation with granulation tissue and polymorphonuclear leukocytes. CONCLUSIONS: To the best knowledge of the authors, this is the first study to develop a novel rat model of polymicrobial peri-implantitis. With modifications to improve implant retention it could offer significant advantages for studies of initiation and progression of peri-implantitis.

Regenerative Needs Following Alveolar Ridge Preservation Procedures in Compromised and Noncompromised Extraction Sockets: A Cone Beam Computed Tomography Study.

PURPOSE: The aim of this study was to evaluate the necessity for additional regenerative procedures following healing of compromised and noncompromised extraction sockets with alveolar ridge preservation procedures through the use of virtual implant imaging software. MATERIALS AND METHODS: The cohort was comprised of 87 consecutive patients subjected to a single maxillary tooth extraction with an alveolar ridge preservation procedure for subsequent implant placement. Patients were divided into two main groups based on the integrity of the buccal bone plate following teeth extraction. Patients in the compromised socket (CS) group (n = 52) had partial or complete buccal bone plate loss, and patients in the noncompromised socket (NCS) group (n = 35) exhibited no bone loss of their socket walls following tooth extraction. Following 4 to 6 months of healing, all patients had a cone beam computed tomography (CBCT) study. Root-formed implants were placed virtually in an ideal prosthetic position. The number of implants per group and location (anterior, premolar, molar) exhibiting exposed buccal implant surface was calculated. RESULTS: In the CS group, 5 out of 19 anterior implants (26.3%), 4 out of 14 premolar implants (28.5%), and 7 out of 19 molar implants (36.8%) had exposed buccal surfaces. In the NCS group, 4 out of 9 anterior implants (44.4%), 2 out of 9 premolar implants (22.2%), and 4 out of 17 molar implants (23.5%) had exposed buccal surfaces. There were no statistically significant differences for intragroup and intergroup comparisons (χ² test, P > .05). CONCLUSION: This study failed to find statistically significant differences in the frequency of implants with exposed buccal surfaces placed virtually, following treatment of compromised and noncompromised sockets. A high proportion (22% to 44%) of sites had implants that potentially needed additional regenerative procedures.

Bacterial Colonization of the Implant-Abutment Interface (IAI) of Dental Implants with a Sloped Marginal Design: An in-vitro Study.

PURPOSE: The aim of this study is to utilize an in vitro dynamic loading model to assess the potential risk of bacterial invasion into the Implant Abutment Interface (IAI) microgap of dental implants with sloped marginal design. MATERIALS AND METHODS: Forty implants were divided into two groups (n = 20 per group) based on implant marginal design. Group 1 was comprised of implants with Morse-taper connection and conventional marginal design that connected to titanium abutments. Group 2 was comprised of implants with Morse-taper connection and sloped marginal design that connected to titanium abutments. The specimens were immersed in a bacterial solution of E. coli and loaded with 500,000 cycles of 160N using a chewing simulator. Following disconnection of fixtures and abutments, microbial samples were taken from the threaded portion of the abutment, plated and cultured under appropriate conditions. RESULTS: Ten out of twenty implants of Group 1 and eight out of twenty implants of Group 2 had IAI microgaps colonized by E. Coli. There was not a statistically significant difference in the mean number of E. Coli CFU detected between implants of Group 1 (mean 19.2, SD 23.6) and Group 2 (mean 12.5, SD18.9) (p > .05). CONCLUSIONS: The present study demonstrated that implants with a sloped marginal design exhibited similar risk for bacterial invasion into the IAI microgap under in vitro dynamic loading conditions compared to implants with conventional marginal design.

Palatal Augmentation Technique: A Predictable Method to Increase the Palatal Connective Tissue at Donor Sites- A Consecutive Case Series.

The palatal masticatory mucosa between the canine and first molar is the main source of connective tissue graft (CTG) for use in periodontal plastic surgery. The purpose of this study was to evaluate the palatal augmentation technique (PAT) to increase the palatal connective tissue donor area using a collagen sponge inserted between the palatal flap and bone. The 26 patients enrolled in this study were referred for root coverage and ridge augmentation procedures. All patients lacked adequate donor palatal tissue thickness. The PAT uses a full-thickness flap and insertion of a sterile lyophilized bovine collagen sponge between the flap and bone. The palatal thickness was clinically assessed before and after collagen sponge insertion. A manual probe was inserted in the mucosal surface perpendicular to the long axis of each tooth approximately 6 mm from the gingival margin. Probing depth (PD) and recession (REC) were also recorded. Treatment with PAT resulted in a statistically significant increase in the palatal thickness. The overall mean increase was from 2.03 mm before surgery to 3.57 mm after surgery, with no major alterations in PD and REC. Healing proceeded uneventfully and occurred by primary intention. PAT appeared to be a predictable procedure to create connective tissue donor graft in deficient areas and had uneventful postoperative healing.

Facial Peri-implant Soft Tissue Topography of Posterior Single Implant-Supported Restorations and Relationship to Adjacent Teeth: A Retrospective Analysis.

PURPOSE: The aim of this study was to retrospectively evaluate the factors affecting facial peri-implant mucosa topography of posterior single implant-supported restorations. MATERIALS AND METHODS: The cohort comprised 25 patients with a single implant-supported restoration with platform switching and Morse taper-connection implants. Patients were divided into three groups based on facial soft tissue topography. Patients of group A (n = 8), group B (n = 9), and group C (n = 8) had a facial peri-implant tissue margin at the level of, coronal to, and apical to the zenith of the facial gingival margins of the adjacent teeth, respectively. Variables possibly associated with the facial peri-implant tissue margin level were obtained from clinical measurements, periapical radiographs, and cone beam computed tomograms. RESULTS: Implants in group C were placed in a more subcrestal position than implants of group B (1.50 ± 0.53 mm vs 0.44 ± 0.88 mm). Implants in group C had their platform in a more apical position in relation to the bone level of the adjacent teeth than implants of group B (3.45 ± 1.32 mm vs 1.53 ± 1.17 mm). The horizontal distance between adjacent teeth was greater for group C than for group A and group B (13.53 ± 2.37 mm vs 10.65 ± 2.09 mm and 9.82 ± 1.77 mm, respectively). CONCLUSION: In this study, facial peri-implant mucosa margins for implants in the posterior region with platform switching and a Morse taper connection were significantly affected by the distances from the implant platform to the buccal aspect of the ridge at the time of implant placement and from the implant platform to the bone level of the adjacent teeth and by the horizontal spaces between the adjacent teeth.