Internal contamination of a 2-component implant system after occlusal loading and provisionally luted reconstruction with or without a washer device

Performance of different abutment/implant joints as a result of a sealing agent

Purpose This in vitro study aimed to evaluate the effectiveness of a sealing agent in sealing the abutment/implant interface and the preload maintenance of retaining screws after mechanical cycling.Methods Six groups (n = 12) were evaluated according to the abutment/implant system (external-hexagon implant and UCLA abutments, EHU; Morse taper implant and UCLA abutments, MTU; and Morse taper implant and flexcone abutments, MTF) and the presence of an anaerobic gel sealing agent (control group, no sealing agent; experimental group, sealing agent). Toluidine blue (0.7 μL) was inserted into each implant and the abutments were attached to the implants using a digital torque wrench to evaluate the sealing of the abutment/implant interface. The specimens were tested through mechanical cycling (1 × 10⁶ cycles, 2 Hz, and 130 N). Dye release from the abutment/implant interface was analyzed using a spectrophotometer, and the reverse torque values were obtained using a digital wrench. Reverse torque and dye release data were measured after mechanical cycling and analyzed using ANOVA and Tukey's test (α =.05).Results All experimental groups showed higher reverse torque values than the control groups (P <.05). In general, the MTU and MTF experimental groups, as well as the MTF control group, showed no significant dye release at different periods (P >.05).Conclusions The use of a sealing agent improved the preload maintenance of screw-retained implant-supported prostheses. The sealing agent was effective in sealing the Morse taper connection.

Effect of sealing gel on the microleakage resistance and mechanical behavior during dynamic loading of 3 implant systems

STATEMENT OF PROBLEM

Sealing products have been produced to reduce microleakage at the implant abutment interface. However, little is known about their effectiveness and any alterations in mechanical behavior of implant systems with their application.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of a silicone sealing gel on implant abutment interface microleakage, abutment screw torque loss, and thread wear of implant systems in a simulated oral environment.

MATERIAL AND METHODS

Five specimens each of 3 implants systems (Nobel, Straumann, and WEGO) that included sealed and unsealed groups were analyzed (N=30). Before assembling the components, toluidine blue solution was injected to the implant intaglio cavity to evaluate implant abutment interface microleakage. After tightening to the recommended torque, 20 to 200 N of 30-degree off-axis dynamic force was applied at 2 Hz for 48 hours. The toluidine blue solution was extracted to test optical density values at 1, 3, 9, 24, 33, and 48 hours. Detorque values were measured before and after cycling loading, and torque loss rates were calculated. The abutment screw morphologies were observed by using scanning electron microscopy. The coefficient of friction tendency of applying sealing gel was explored with a ball-on-flat configuration. One-way ANOVA and Student t test were used for statistical analysis (α=.05).

RESULTS

The optical density value increased with the loading time, especially for Straumann group. The sealing gel decreased the implant abutment interface microleakage of Straumann assemblies after cyclic loading of 9 hours (P=.044), whereas no statistical difference was found for Nobel (P=.140) or WEGO groups (P=.402) at 6 time points. Torque loss occurred during tightening and further increased after dynamic cyclic load in each group. Among the 3 implant systems, Straumann implants reported the best antiloosening property (P<.001). The application of sealing gel reduced the initial (P=.048) and final (P=.032) torque loss rate in all the 3 systems. Scanning electron microscopy observations revealed the bottom thread tended to have more abrasion than the first thread. After applying sealing gel, less thread abrasion was found in Nobel and WEGO assemblies, whereas the protective effect was not evident for the Straumann group. The coefficient of friction of sealed group (0.17 ±0.026) was significantly (P=.012) lower than that of unsealed group (0.24 ±0.044).

CONCLUSIONS

The silicone sealing gel improved the immediate fastening and long-term antiloosening performances of 3 implant systems, decreased the implant abutment interface microleakage of Straumann system, and reduced abutment screw thread abrasion of the Nobel and WEGO systems.

Control of Peri-Implant Mucous Inflammation by Using Chlorhexidine or Ultraviolet C Radiation for Cleaning Healing Abutments. Double-Blind Randomized Clinical Trial

Two-phase implants must be exposed to the external environment after the period of osteointegration has elapsed. For this purpose, a healing abutment is placed passing through the mucosa while forming the emergence profile. The continuous connection and disconnection can lead to an alteration in the tissue maturation, both because of the contact of bacterial plaque and because of the mechanical trauma that involves its manipulation, manifesting with different degrees of erythema or bleeding. To assess whether this epithelium disruption can be counteracted, a blinded study design was developed on 150 unitary implant patients divided into three groups (n = 50), applying chlorhexidine (group 1), ultraviolet C (UV-C) at a wavelength of 254 nm (group 2)and no treatment as a control group (group 3), during each of the disconnections and connections during the prosthodontic treatment (1 time per week for four weeks). All groups showed a better epithelium aspect at the end of the evaluation. Although there were no statistically significant differences in the degree of inflammation, the UV-C treated group had the lowest plaque accumulation, and the highest was for the chlorhexidine-treated group.

Bacterial Leakage at Implant-Abutment Interface With Different Intermediate Materials

A gap exists at the implant-abutment interface in two-piece implants and can serve as a reservoir of bacteria and compromise the health of peri-implant tissue. This study aimed to compare the effect of different intermediate materials on bacterial leakage at the implant-abutment interface. A total of 75 implants were divided into 5 groups (n = 15) based on the material applied at the implant-abutment connection: (1) Atridox, (2) chlorhexidine, (3) Gapseal silicone, (4) saliva, and (5) no material. All the implants were inoculated with 0.1 μL of Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) suspension, and then the respective material was applied. The abutments were connected to the implants, and appropriate torque was applied as recommended by the manufacturer (Implantium, Dentium, Korea, Seoul). Bacterial leakage was determined by evaluating the turbidity of the broth. Bacterial contamination was found in all samples at different times; in groups 1, 2 and 3, contamination was noted after 7, 5, and 6 days, respectively, on average. Contamination occurred averagely after 4 days in groups 4 and 5. The present study showed that Atridox applied at the implant-abutment interface significantly delayed bacterial leakage.

Efficacy of a Polyglycol Dimethacrylate-Based Adhesive in Sealing the Implant-Abutment Interface

PURPOSE

The purpose of this study was to assess the effectiveness of a polyglycol dimethacrylate-based adhesive in preventing bacterial leakage through implant-abutment interfaces (IAIs).

MATERIALS AND METHODS

After implant installation, the adhesive was applied in the experimental group (n = 10). None was applied in the control group (n = 10). Samples were collected from the inner walls of implants on days 0 and 90. The real-time polymerase chain reaction was used to detect bacterial DNA.

RESULTS

All samples from the control group, versus 30% from the experimental group, harbored bacterial DNA on day 90.

CONCLUSIONS

This polyglycol dimethacrylate-based adhesive may be used to seal the IAI. Further studies are warranted to verify its effectiveness over longer time periods.

Dental materials and their performance for the management of screw access channels in implant-supported restorations

Unsuccessfully sealed screw access channels of prosthetic implant abutments may lead to malodor or peri-implant diseases in gingival tissues adjacent to implant-supported restorations. Therefore, 72 sets of screw channel analogs with six different materials incorporated (Polytetrafluoroethylene (PTFE), wax, gutta-percha, cavit, endofrost-pellets and cotton pellets) were exposed (2.5 h, 37°C) to Streptococcus mutans, oralis and Candida albicans suspensions. Bacterial adherence was quantified by using the fluorescence dye, Alamar Blue/resazurin, and an automated multifunctional reader. For quantification of fungal adherence the ATP-based bioluminescence approach was used. High relative fluorescence and luminescence intensities (>10,000), indicating high adhesion of streptococci and fungi were found for cotton and endofrost-pellets and low intensities (<5,000) for wax, gutta-percha, cavit and PTFE. The quantity of bacterial and fungal adhesion differed significantly between the assessed various sealing materials. In conclusion and within the limitations of this study, wax, gutta-percha, cavit and PTFE should be preferred as sealing materials.

Microbial colonization at the implant-abutment interface and its possible influence on periimplantitis: A systematic review and meta-analysis

PURPOSE

The aim of this systematic review and meta-analysis was to evaluate the microbial colonization at the implant-abutment interfaces (IAI) on bone-level implants and to identify possible association with peri-implant conditions.

STUDY SELECTION

The focus question aimed to answer whether two-piece osseointegrated implants, in function for at least 1 year, in human, relate to higher bacterial count and the onset of periimplantitis, compared to healthy peri-implant conditions. Search strategy encompassed the on-line (MedLine, Google scholar, Cochrane library) literature from 1990 up to March 2015 published in English using combinations of MeSH (Medical Subject Headings) and search terms. Quality assessment of selected full-text articles was performed according to the ARRIVE and CONSORT statement guidelines. For data analysis, the total bacterial count of Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Prevotella intermedia, and Fusobacterium nucleatum was calculated and compared to IAI with or without peri-implant pathology.

RESULTS

A total of 14 articles, reporting data from 1126 implants, fulfilled the inclusion criteria and subjected to quality assessment. The selected studies revealed contamination of the IAI, in patients who received two-piece implant systems. Meta-analysis indicated significant difference in total bacterial count between implants affected by periimplantitis versus healthy peri-implant tissues (0.387±0.055; 95% CI 0.279-0.496). Less bacterial counts were identified in the healthy IAI for all the investigated gram-negative bacteria except for T. forsythia.

CONCLUSIONS

Significantly higher bacterial counts were found for periodontal pathogenic bacteria within the IAI of implants in patients with periimplantitis compared to those implants surrounded by healthy peri-implant tissues.

A Novel Approach to Prove Bacterial Leakage of Implant-Abutment Connections In Vitro

Bacterial leakage from the implant-abutment-interface (IAI) is suspected of contributing to the development of peri-implantitis. The aim of the study was to develop a straightforward test setup to evaluate the bacterial leakage of the IAI of 2-piece implant systems under laboratory conditions. A test suspension of Enterococcus faecium was injected into 7 implants (PerioType Rapid Implants) prior to abutment fixation. The IAI was covered by kanamycin aesculn azide agar (KAAA), which serves as an optical indicator for E. faecium. The specimens were cyclically loaded with a force of 120 N for up to 1 000 000 cycles in a universal testing machine in accordance with the ISO 14801:2007 standard. The color change of the KAAA was recorded. Three of the 7 implants showed bacterial leakage before the cyclic loading test started. The bacterial tightness of the IAIs of the 4 remaining implants lasted for 35 680 ± 22 467 cycles on average. The experimental setup at hand provides the means for a straightforward evaluation of the bacterial tightness of the IAI of 2-piece dental implants.

Peri-implant Inflammation Defined by the Implant-Abutment Interface

An implant-abutment interface at the alveolar bone crest is associated with sustained peri-implant inflammation; however, whether magnitude of inflammation is proportionally dependent upon interface position remains unknown. This study compared the distribution and density of inflammatory cells surrounding implants with a supracrestal, crestal, or subcrestal implant-abutment interface. All implants developed a similar pattern of peri-implant inflammation: neutrophilic polymorphonuclear leukocytes (neutrophils) maximally accumulated at or immediately coronal to the interface. However, peri-implant neutrophil accrual increased progressively as the implant-abutment interface depth increased, i.e., subcrestal interfaces promoted a significantly greater maximum density of neutrophils than did supracrestal interfaces (10,512 ± 691 vs. 2398 ± 1077 neutrophils/mm2). Moreover, inflammatory cell accumulation below the original bone crest was significantly correlated with bone loss. Thus, the implant-abutment interface dictates the intensity and location of peri-implant inflammatory cell accumulation, a potential contributing component in the extent of implant-associated alveolar bone loss.

Microleakage of bacteria in different implant-abutment assemblies: an in vitro study

PURPOSE

The aim of the present in vitro study was to evaluate the leakage observed for 2 different microbial species at the level of the implant-abutment (I-A) interface, and the marginal fit and size of microgap at the I-A interface in 2 different implant connections.

METHODS

Ten specimens of each group were tested. The inner parts of 5 implants per group were inoculated with 0.1 μL of a viable Enterococcus faecalis suspension and 5 implants per group with Aggregatibacter actinomycetemcomitans. All of the vials containing the control specimens were incubated at 37°C under aerobic condition for E. faecalis and 37°C in presence of 5% CO2 for A. actinomycetemcomitans. They were maintained for 14 days, and the possible penetration of bacterial suspension into the surrounding solution was determined by the observation of turbidity of the broth. The I-A interface was evaluated for size of microgap and measured under SEM. Five implants of each group were evaluated. The marginal fit between implant and abutment was measured at 8 random locations in each assembly, under different magnifications at the interface.

RESULTS

No leakages through the I-A interface were demonstrated for either type of connection evaluated. The microgap values of all I-A interfaces ranged from 0.008 to 2.009 μm; the differences between the 2 systems were statistically significant.

CONCLUSIONS

The present study demonstrated that a good marginal fit of implant components seemed to be able to prevent bacterial leakage.

Influence of the Prosthetic Index Into Morse Taper Implants on Bacterial Microleakage

PURPOSE

To evaluate the influence of Morse taper implant index on microleakage.

MATERIALS AND METHODS

Thirty implants and abutments were divided into 3 groups (n = 10): CM1 (universal post and implant without index), CM2 (universal post and implant with index), and CM3 (abutment and implant with index). To evaluate the microleakage from the implant inner part, the implants were inoculated with Streptococcus sanguinis solution at a 0.5 McFarland and incubated for 7 days at 37°C in Eppendorf tubes with sterile broth. To evaluate the microleakage into the inner part of implant, these were inoculated with sterile Schaedler broth and immersed in a Fusobacterium nucleatum solution at a 0.5 McFarland. The samples were incubated for 30 days in an anaerobic chamber.

RESULTS

Nine samples of each group of the first methodology showed no presented bacterial contamination. No samples of the second methodology demonstrated turbidity of the broth.

CONCLUSION

The presence of the prosthetic internal index had no influence on bacterial microleakage of Morse taper implants under static conditions, for both methodologies.

Efficacy of Gutta-Percha and Polytetrafluoroethylene Tape to Microbiologically Seal the Screw Access Channel of Different Prosthetic Implant Abutments

PURPOSE

To evaluate in vitro, the efficacy of gutta-percha (GP) and polytetrafluoroethylene (PTFE) tape to act as a seal against the penetration of Escherichia coli through prosthetic implant abutments (PIA) with external hexagon (EH) and morse taper (MT) connections.

MATERIALS AND METHODS

120 sets of implant analogs with their respective PIA were used. 60 sets from each system were divided into four groups (n = 15): I - GP sealing; II - PTFE tape sealing; III - no sealing (NS) and IV - negative control. Microbiological challenge was performed by placing bacterial colonies inside the titanium PIA before screwing them into their respective analogs. Each set was immersed in 5 mL of BHI and incubated for 14 days with daily checks for contamination, according to the nutrient medium turbidity.

RESULTS

The type of seal used influenced microbial penetration at all evaluation times (p < 0.05). Compared to GP, PTFE led to an increase in turbidity and its effectiveness against microbial penetration was equivalent to group NS. When the sealing efficacy of each group was compared in terms of time, Cochran's Q test revealed that in the two groups sealed with PTFE, there was a progressive increase in the number of turbid nutrient media (p < 0.0001), while in the group sealed with GP, this was only observed in the MT system (p = 0.0310).

CONCLUSIONS

Sealing the PIA channel with GP was a significantly superior approach to sealing it with PTFE tape. PTFE tape or NS led to a progressive increase in microbiological leakage over time in PIA channels, however, this only occurred with GP in the MT system.

[Comparison of leakage at the implant to abutment connection in several implants types using a gas flow method]

INTRODUCTION

The aim of this study was to compare the leakage at the implant to abutment connection in several implants, using a new gas diffusion method.

MATERIAL AND METHODS

Sixty-eight implants of 13 different types were used. Nitrogen leaking was measured after screwing the connections to the torque levels recommended by the manufacturers.

RESULTS

A significant tightness difference was observed between the different implant types. This difference cannot be explained by the various connection designs (flat, conical) or by the various torques recommended by the manufacturers.

CONCLUSION

The authors suggest that the tightness difference between the various implant systems could be mainly associated with quality and precision of machining.

In Vitro Microbiological Analysis of Bacterial Seal at the Implant-Abutment Interface Using Two Morse Taper Implant Models

The objective of this study was to evaluate the bacterial seal at the implant-abutment interface using two morse taper implant models, by means of an in vitro microbiological analysis. For that were used 15 implants with mini-abutments tightened by friction, no screws (Group 1); and 30 implants with screw-tightened abutments, of which 15 received 20 N.cm of closing torque (Group 2) and the other 15 received 30 N.cm (Group 3). Microbiological analysis was carried out using colonies of Escherichia coli transported directly from a culture dish to the prosthetic component. Friction implants (Group 1) were activated by tapping and a torque wrench was used for screw-tightened implants (Groups 2 and 3). Each abutment/implant set was immersed in test tubes containing 5 mL of brain-heart infusion broth and incubated at 37 °C for 14 days, observed daily for the presence of contamination. A statistically significant difference was observed regarding the number of contaminated implants. There was greater contamination in Group 2 implants (p<0.05), with no statistically significant difference between the other groups (Group 1 = 20% and Group 3 = 0%). It was concluded that there was no significant difference in in vitro bacterial sealing between implants with mini-abutments tightened by friction without screws and implants with screw-tightened abutments with 30 N.cm of closing torque. The difference in closing torque altered the in vitro sealing ability of the tested abutments, with a greater contamination for components that received a closing torque of 20 N.cm.

Micro-leakage at the implant-abutment interface with different tightening torques in vitro

Objectives

This study evaluated the microleakage at the implant/abutment interface of external hexagon (EH) implants and abutments with different amounts of bacteria and tightening torques.

Material and Methods

A bacterial suspension was prepared to inoculate the implants. The first phase of this study used nine EH implants and abutments that were divided into three groups with different amounts of bacterial suspension (n=3): V0.5: 0.5 µL; V1.0: 1.0 µL e V1.5: 1.5 µL, and tightened to the manufacturer's recommended torque. The second phase of this experiment used 27 assemblies that were similar to those used in the first phase. These samples were inoculated with 0.5 µL of bacterial suspension and divided into three groups (n=9). T10: 10 Ncm; T20: 20 Ncm and T32: 32 Ncm. The samples were evaluated according to the turbidity of the broth every 24 hours for 14 days, and the bacteria viability was tested after that period. The statistical evaluation was conducted by Kruskal-Wallis testing (p<.05).

Results

During the first phase, groups V1.0 and V1.5 was presented with bacterial contamination in all samples after 24 h. During the second phase, two samples from group T10 and one from T20 presented positive results for bacterial contamination. Different amounts of bacterial solution led to overflow and contamination during the first 24 h of the experiment. The tightening torques did not statistically affect the microleakage in the assemblies. However, the group that was tightened to 32 Ncm torque did not show any bacterial contamination.

Conclusion

After 14 days of experimentation, the bacteria were proven to remain viable inside the implant internal cavity.

Connecting accuracy of interchanged prosthetic abutments to different dental implants using scanning electron microscopy

The present study evaluated the interchangeability of prosthetic components for external hexagon implants by measuring the precision of the implant/abutment (I/A) interface with scanning electron microscopy. Ten implants for each of three brands (SIN, Conexão, Neodent) were tested with their respective abutments (milled CoCr collar rotational and non-rotational) and another of an alternative manufacturer (Microplant) in randomly arranged I/A combinations. The degree of interchangeability between the various brands of components was defined using the original abutment interface gap with its respective implant as the benchmark dimension. Accordingly, when the result for a given component placed on an implant was equal to or smaller then that gap measured when the original component of the same brand as the implant was positioned, interchangeability was considered valid. Data were compared with the Kruskal-Wallis test at 5% significance level. Some degree of misfit was observed in all specimens. Generally, the non-rotational component was more accurate than its rotational counterpart. The latter samples ranged from 0.6-16.9 µm, with a 4.6 µm median; and the former from 0.3-12.9 µm, with a 3.4 µm median. Specimens with the abutment and fixture from Conexão had larger microgap than the original set for SIN and Neodent (p<0.05). Even though the latter systems had similar results with their respective components, their interchanged abutments did not reproduce the original accuracy. The results suggest that the alternative brand abutment would have compatibility with all systems while the other brands were not completely interchangeable.

Sealing Capability and SEM Observation of the Implant-Abutment Interface

To evaluate the sealing capability of external hexagon implant systems and assess the marginal fit, two groups (n = 10 each) were employed: SIN (Sistema de Implantes Nacional, Brazil) and Osseotite, (Biomet 3i, USA). Sealing capability was determined by placing 0.7 μL of 1% acid-red solution in the implant wells before the torque of their respective abutments. Specimens were then placed into 2.5 mL vials filled with 1.3 mL of distilled water with the implant-abutment interface submerged. Three samples of 100 μL water were collected at previously determinate times. The absorbance was measured with a spectrophotometer, and the data were analyzed by Two-way ANOVA (P < .05) and Tukey's test. Marginal fit was determined using SEM. Leakage was observed for both groups at all times and was significantly higher at 144 hrs. SEM analysis depicted gaps in the implant-abutment interface of both groups. Gaps in the implant-abutment interface were observed along with leakage increased at the 144 hrs evaluation period.

Development of a new quantitative gas permeability method for dental implant-abutment connection tightness assessment

Background

Most dental implant systems are presently made of two pieces: the implant itself and the abutment. The connection tightness between those two pieces is a key point to prevent bacterial proliferation, tissue inflammation and bone loss. The leak has been previously estimated by microbial, color tracer and endotoxin percolation.

Methods

A new nitrogen flow technique was developed for implant-abutment connection leakage measurement, adapted from a recent, sensitive, reproducible and quantitative method used to assess endodontic sealing.

Results

The results show very significant differences between various sealing and screwing conditions. The remaining flow was lower after key screwing compared to hand screwing (p = 0.03) and remained different from the negative test (p = 0.0004). The method reproducibility was very good, with a coefficient of variation of 1.29%.

Conclusions

Therefore, the presented new gas flow method appears to be a simple and robust method to compare different implant systems. It allows successive measures without disconnecting the abutment from the implant and should in particular be used to assess the behavior of the connection before and after mechanical stress.

Microbiological and Biochemical Effectiveness of an Antiseptic Gel on the Bacterial Contamination of the Inner Space of Dental Implants: A 3-Month Human Longitudinal Study

Microbial penetration inside the implant's internal cavity produces a bacterial reservoir that is associated with an area of inflamed connective tissue facing the fixture-abutment junction. The aim of this clinical trial is to evaluate the effectiveness of a 1% chlorhexidine gel on the internal bacterial contamination of implants with screw-retained abutments and on the level of AST secreted in peri-implant crevicular fluid. Twenty-five patients (aged 29 to 58 years) each received one implant. Three months after the end of the restorative treatment, and immediately after a clinical and radiographic examination and the abutment removal, microbiological samples were obtained from the internal part of each fixture and biochemical samples were collected by peri-implant sulci. The patients were then divided into two groups: the control (CG; n=10) and test (TG; n=15) groups. The CG had the abutment screwed into place and the crown cemented without any further intervention. In contrast, before the abutment placement and screw tightening, the TG had the internal part of the fixture filled with a 1% chlorhexidine gel. Three months later, the same clinical, microbiological and biochemical procedures were repeated in both groups. Total bacterial count, specific pathogens and AST activity were detected. The clinical parameters remained stable throughout the study. From baseline to the 3-month examination, the total bacterial counts underwent a significant reduction only in the TG. In contrast, the AST activity showed a significant increase in the CG. The administration of a 1% chlorhexidine gel appears to be an effective method for the reduction of bacterial colonization of the implant cavity and for safeguarding the health status of peri-implant tissue over a 3-month administration period.

Cross-sectional analysis of the implant?abutment interface

The purpose of this study was to develop a technique to evaluate the implant-abutment gap of an external hexagon implant system as a function of radius. Six implants of 3.75 mm in diameter (Conexao Sistema de Protese Ltda, Sao Paulo, Brazil) and their respective abutments were screw connected and torqued to 20 N cm(-1). The implants were mounted in epoxy assuring an implant long-axis position perpendicular to the vertical axis. Each implant was grounded through its thickness parallel to implant long-axis at six different distance interval. Implant-abutment gap distances were recorded along the implant-abutment region for each section. Individual measurements were related to their radial position through trigonometric inferences. A sixth degree polynomial line fit approach determined radial adaptation patterns for each implant. Micrographs along implant sections showed a approximately 300 mum length implant-abutment engagement region. All implants presented communication between external and internal regions through connection gaps and inaccurate implant-abutment alignment. Average gap distances were not significantly different between implants (P > 0.086). Polynomial lines showed implant-abutment gap values below 10 mum from 0 mum to approximately 250 mum of the implant-abutment engagement region. Gap distances significantly increased from approximately 250 mum to the outer radius of the implant-abutment engagement region. The technique described provided a broader scenario of the implant-abutment gap adaptation compared with previous work concerning implant-abutment gap determination, and should be considered for better understanding mechanical aspects or biological effects of implant-abutment adaptation on peri-implant tissues.

In vitro sealing ability of two materials at five different implant-abutment surfaces

BACKGROUND

The aim of the present study was to test the sealing ability of two materials at five different implant-abutment surfaces.

METHODS

In the first phase, 2 mul brain-heart infusion (BHI) broth was deposited into the implant wells and glass culture tubes. A varnish or silicon sealant was applied at the cervical implant portion of experimental groups. The control group remained unexposed. The abutments were torque-tightened to 20 Ncm with a manual torque driver. Implants were immersed in 4 ml BHI broth at 37 degrees C for 2 hours to exclude contamination. In the second phase, 100 mul Enterococcus faecalis American Type Culture Collection (ATCC) strain 29212 was deposited into the glass culture tubes. After periods of 7, 14, 21, 35, 49, and 63 days, the sealing capacity was checked. Abutments were removed, and a sterile paper cone collected material inside implant bodies. This material was transferred to new tubes with BHI to verify the presence of cloudy broths within 24 to 48 hours.

RESULTS

There were no statistically significant differences between the two materials for each time period (Fisher exact test; P >0.05). Group E showed the least level of sealing ability (six implants contaminated), whereas group T showed the highest level (only two implants).

CONCLUSIONS

1) Materials tested were not able to prevent contamination over 63 days. 2) Bacterial contamination was verified after 14 and 35 days in the control and experimental groups, respectively. 3) Although materials tested had demonstrated similar sealing capacities, dental implants showed bacterial contamination regardless of their external or internal hexagonal configurations.

Role of the microgap between implant and abutment: a retrospective histologic evaluation in monkeys

BACKGROUND

It has been hypothesized that a certain width of the peri-implant mucosa is required to enable a proper epithelial-connective tissue attachment and, if this soft tissue dimension is not adequate, bone resorption will occur to ensure the establishment of attachment with an appropriate biological width. The reason for the accelerated bone loss around submerged 2-piece implants in the first year after the restoration is not known, but one possibility is that the gap between components plays a role in this process. Recent studies have shown that for all 2-part implants, the bone crest level changes appeared dependent on the location of the microgap.

METHODS

The aim of the present study was a retrospective histologic evaluation in monkeys of the bone response to implants inserted 1 to 2 mm above the alveolar crest (group 1, 15 implants), at the level of the alveolar crest (group 2, 12 implants), or 1 to 1.5 mm below the alveolar crest (group 3, 13 implants). These implants had been early loaded, immediately loaded, and inserted immediately postextraction.

RESULTS

In group 1, a 0.13 +/- 0.12 mm bone increase in a coronal direction was seen. In group 2, a 2.1 +/- 0.29 mm vertical bone loss was present. In group 3, a mean 3.6 +/- 0.46 mm vertical bone loss extending in an apical direction was observed. Statistically significant differences were observed between all 3 groups.

CONCLUSIONS

Our results confirm data published previously that if the microgap was moved coronally away from the alveolar crest, less bone loss would occur and if the microgap was moved apical to the alveolar crest, greater amounts of bone resorption were present. This remodeling is not dependent on early and immediate loading of the implants or on immediate postextraction insertion.