Internal Implant-abutment Research Articles

Comparative Analysis of Microbial Leakage in Implant Recess of Three Different Internal Implant Abutment Connections: An In Vitro Study

Comparative Analysis of Microbial Leakage in Implant Recess of Three Different Internal Implant Abutment Connections: An In Vitro Study

Assessment of Microgap and Bacterial Leakage of Two Types of Internal Implant-Abutment Union.

The current research was done to assess microbial seepage of two types of internal implant-abutment connections. Twenty dental implants are categorized into two groups. Group A fixtures with an internal hexagonal geometry and group B fixtures with a tri-lobe internal connection. All implant-abutment assemblies underwent a three-week incubation period at 37°C in sterile tubes containing 5 mL of Staphylococcus aureus broth culture. Through the use of Gram stain and biochemical processes, the resultant colonies were recognized. The mean Log10 colony forming unit (CFU) in group A was 8.4 and in group B was 7.2. The variation between both groups was found to be considerable (P < 0.05). Microgap was more in group B compared to group A. Bacteria may infiltrate the small area between the implant and the abutment. Compared to dental implant fixtures with a tri-lobe internal connection, there was a noticeably higher Log10 CFU in dental implant fixtures with an internal hexagonal geometry.

Internal Implant-Abutment Interface of CAD/CAM Milled Bars Fabricated with Different Materials

Internal Implant-Abutment Interface of CAD/CAM Milled Bars Fabricated with Different Materials

Risk Indicators Affecting the Survival of the Mandibular First Molar Adjacent to an Implant at the Mandibular Second Molar Site: A Retrospective Study.

This study aimed to compare the survival of mandibular first molars (MnM1s) adjacent to implants placed in mandibular second molar sites (ImM2s) with MnM1s adjacent to mandibular second molars (MnM2s) and to investigate risk indicators affecting the survival of MnM1s adjacent to ImM2s. A total of 144 patients who had MnM1s adjacent to ImM2s and MnM1s adjacent to MnM2s on the contralateral side were included in this study. Clinical variables and radiographic bone levels were evaluated. The survival of MnM1s adjacent to ImM2s or MnM2s was evaluated using a Kaplan–Meier analysis and Cox proportional hazards model. The 5-year cumulative survival rates of MnM1s adjacent to ImM2s and MnM2s were 85% and 95%, respectively. MnM1s adjacent to ImM2s of the internal implant-abutment connection type had higher multivariate hazard ratios (HR) for loss. MnM1s that had antagonists with implant-supported prostheses also had higher HR for loss. The multivariate HR for the loss of MnM1s adjacent to ImM2s with peri-implant mucositis was 3.74 times higher than MnM1s adjacent to healthy ImM2s. This study demonstrated several risk indicators affecting the survival of MnM1s adjacent to ImM2s. It is suggested that supportive periodontal and peri-implant therapy combined with meticulous occlusal adjustment can prolong the survival of MnM1s and ImM2s.

SECONDARY ETIOLOGICAL FACTORS IN THE DEVELOPMENT OF PERI-IMPLANTITIS

Purpose: The aim of this review was to investigate the potential impact of secondary etiological factors on the development of peri-implant infections. Results: During the review process we found sufficient evidence to define the following factors as secondary etiological factors for the development of peri-implantitis: a history of periodontitis; implant surface characteristics; suprastructure characteristics; cemented restorations; implant-abutment connection; smoking; diabetes and peri-implant mucosa characteristics. Conclusion: To reduce the risk of peri-implantitis, the following recommendations should be considered: (1) in partially edentulous patients, implant treatment should start after elimination of the periodontal infection and after the establishment of a stable periodontal status; (2) implants should be placed in areas where there is a minimum of 2 mm of keratinized mucosa; (3) an internal implant-abutment connection and screw-retained suprastructures are preferred; (4) supra structures should be planned carefully to facilitate good oral hygiene; and (5) smoking cessation should be promoted and (6) only patients with controlled diabetes should undergo implant placement.

Evaluation of Milled Titanium versus Laser Sintered Co-Cr Abutments on the Marginal Misfit in Internal Implant-Abutment Connection.

The precision of fit at the implant-abutment connection is an important criterion for the clinical success of restorations and implants. Several factors are involved among which are the abutment materials and manufacturing techniques. The aim of this study was to investigate the effect of two materials and methods of manufacturing implant abutments, milled titanium versus laser sintered Co-Cr, on the marginal misfit at the implant-abutment interface. Scanning electron microscopes (SEM) were used to geometrically measure the marginal vertical discrepancy of a total of 80 specimens, classified into eight categories, according to the implant system and abutment. The data were statistically analyzed by Student’s paired t test, one-way and two-way ANOVA with the Bonferroni-Holm correction at the significance level of p = 0.05. Milled titanium abutments demonstrated the lowest misfit values in the implant systems analyzed. The marginal fit of all the groups was within the clinically acceptable range for implant prostheses.

Evaluation of Microleakage and Microgap of Two Different Internal Implant&amp;ndash;Abutment Connections: An In Vitro Study

The higher success rate (>90%) of dental implants over 5 years has made this treatment option favorable for dental surgeons as well as for patients. The present in vitro study was conducted to assess microleakage and microgap of two dissimilar internal implant-abutment associations. Forty dental implants were divided into two groups: trilobe internal connection fixtures in group I and internal hexagonal geometry fixtures in group II. For the immersion of implant abutment assemblies, sterilized tubes containing 4 mL of Staphylococcus aureus broth culture were incubated at 37°C for 2 weeks. Gram's stain and biochemical reactions were used for identification of colonies. The mean log10 colony-forming unit (CFU) in group I was 8.6 and was 9.3 in group II. The disparity among two groups was found to be significant (p < 0.05). The mean microgap in group I was 7.2 μm and was 10.4 μm in group II. The disparity among the two groups was found to be significant (p < 0.05). Authors found that microscopic space between implant and abutment may be the site of penetration of bacteria. There was significant higher log10 CFU in dental implant fixtures with an internal hexagonal geometry compared to the dental implant fixtures with a trilobe internal connection. Microscopic space between implant and abutment may be the site of penetration of bacteria. This information will help to avoid microleakage to improve implant success rate.

European Association for Osseointegration Delphi study on the trends in Implant Dentistry in Europe for the year 2030.

To assess the potential trends for the year 2030 in dental implant dentistry in Europe using the Delphi methodology. A steering committee and a management team of experts in implant dentistry were created and validated a questionnaire including 60 questions, divided in eight topics. The survey was conducted in two rounds using an anonymous questionnaire, which provided the participants in the second round with the results of the first. Each question had three possible answers, and the results were expressed as percentages. A total of 138 experts were invited to participate in the survey. From all the invited experts, 52 answered in both the first and second rounds. Three different consensus categories were established based on the percentage of agreement: no consensus (<65%); moderate consensus (65%-85%); and high consensus (≥86%). Within the topic categories, a consensus was reached (mainly moderate consensus) for the majority of questions discussed among experts during a face to face consensus meeting. However, consensus was not reached for a small number of questions/topics. About 82% of the questions reached consensus. The consensus points towards a lower number of implants to replace chewing units, with implants surfaces made of bioactive materials with reduced micro-roughness using mainly customized abutments with polished surfaces and an internal implant-abutment connection (85%). CBCT-3D technologies will be the main tool for pre-surgical implant placement diagnosis together with direct digital restorative workflows. There will be an increase in the incidence of peri-implantitis, although there will be more efficient interventions its treatment and prevention.

Three-Dimensional Finite Element Analysis on Stress Distribution of Internal Implant-Abutment Engagement Features.

To investigate the stress distribution in an implant-abutment complex with a preloaded abutment screw by comparing implant-abutment engagement features using three-dimensional finite element analysis (FEA). For FEA modeling, two implants-one with a single (S) engagement system and the other with a double (D) engagement system-were placed in the human mandibular molar region. Two types of abutments (hexagonal, conical) were connected to the implants. Different implant models (a single implant, two parallel implants, and mesial and tilted distal implants with 1-mm bone loss) were assumed. A static axial force and a 45-degree oblique force of 200 N were applied as the sum of vectors to the top of the prosthetic occlusal surface with a preload of 30 Ncm in the abutment screw. The von Mises stresses at the implant-abutment and abutment-screw interfaces were measured. In the single implant model, the S-conical abutment type exhibited broader stress distribution than the S-hexagonal abutment. In the double engagement system, the stress concentration was high in the lower contact area of the implant-abutment engagement. In the tilted implant model, the stress concentration point was different from that in the parallel implant model because of the difference in the bone level. The double engagement system demonstrated a high stress concentration at the lower contact area of the implant-abutment interface. To decrease the stress concentration, the type of engagement features of the implant-abutment connection should be carefully considered.

Stress and strain distribution in three different mini dental implant designs using in implant retained overdenture: a finite element analysis study.

Purpose of this study was to characterize and analyze stress and strain distribution occurring in bone and implants and to compare stress and strain of three different implant designs. Three different mini dental implant designs were included in this study: 1. a mini dental implant with an internal implant-abutment connection (MDIi); 2. a mini dental implant with an external implant-abutment connection (MDIe); 3. a single piece mini dental implant (MDIs). All implant designs were scanned using micro-CT scans. The imaging details of the implants were used to simulate models for FEA. An artificial bone volume of 9×9 mm in size was constructed and each implant was placed separately at the center of each bone model. All bone-implant models were simulatively loaded under an axial compressive force of 100 N and a 45-degree force of 100 N loading at the top of the implants using computer software to evaluate stress and strain distribution. There was no difference in stress or strain between the three implant designs. The stress and strain occurring in all three mini dental implant designs were mainly localized at the cortical bone around the bone-implant interface. Oblique 45° loading caused increased deformation, magnitude and distribution of stress and strain in all implant models. Within the limits of this study, the average stress and strain in bone and implant models with MDIi were similar to those with MDIe and MDIs. The oblique 45° load played an important role in dramatically increased average stress and strain in all bone-implant models. Mini dental implants with external or internal connections have similar stress distribution to single piece mini dental implants. In clinical situations, the three types of mini dental implant should exhibit the same behavior to chewing force.

Effect of the Coronal Wall Thickness of Dental Implants on the Screw Joint Stability in the Internal Implant-Abutment Connection.

To evaluate the effect of implant coronal wall thickness on load-bearing capacity and screw joint stability. Experimental implants were customized after investigation of the thinnest coronal wall thickness of commercially available implant systems with a regular platform diameter. Implants with four coronal wall thicknesses (0.2, 0.3, 0.4, and 0.5 mm) were fabricated. Three sets of tests were performed. The first set was a failure test to evaluate load-bearing capacity and elastic limit. The second and third sets were cyclic and static loading tests. After abutment screw tightening of each implant, vertical cyclic loading of 250 N or static loading from 250 to 800 N was applied. Coronal diameter expansion, axial displacement, and removal torque values of the implants were compared. Repeated measures analysis of variance (ANOVA) was used for statistical analysis (α = .05). Implants with 0.2-mm coronal wall thickness demonstrated significantly low load-bearing capacity and elastic limit (both P < .05). These implants also showed significantly large coronal diameter expansion and axial displacement after screw tightening (both P < .05). Greater vertical load and thinner coronal wall thickness significantly increased coronal diameter expansion of the implant, axial displacement of the abutment, and removal torque loss of the abutment screw (all P < .05). Implant coronal wall thickness of 0.2 mm produces significantly inferior load-bearing capacity and screw joint stability.

Three-Dimensional Finite Element Analysis of the Stress Distribution at the Internal Implant-Abutment Connection.

This study investigated stress distribution in four different implant-abutment interface conditions in the internal tapered connection implant system. Four different implant diameters (3.5 mm, 4.0 mm, 4.5 mm, and 5.0 mm) and two abutment types (hexagonal and conical) were simulated. Four unique implant-abutment interface conditions were assumed based on wall thickness, mating surface length, distance to the vertical stop, and abutment shape. Axial and oblique loading was applied during abutment screw preload, and the Von Mises stresses were measured at the implant-abutment and abutment-screw interfaces. The implant-abutment interface stress decreased as the wall thickness increased. As the mating surface increased, the stress distribution trended downward, and when the distance to the implant vertical stop was 0 μm, the Von Mises stress was extremely high at the vertical stop. Despite their different shapes, the abutments showed similar stress distributions. However, the maximum Von Mises stress was higher in the conical connection than in the hexagonal connection, particularly at the contralateral side to loading. To decrease the stress distribution at the implant-abutment interface, the implant wall thickness, mating surface contact length, distance to the vertical stop, and abutment shape should be carefully considered.

Axial displacement of external and internal implant-abutment connection evaluated by linear mixed model analysis.

To analyze the axial displacement of external and internal implant-abutment connection after cyclic loading. Three groups of external abutments (Ext group), an internal tapered one-piece-type abutment (Int-1 group), and an internal tapered two-piece-type abutment (Int-2 group) were prepared. Cyclic loading was applied to implant-abutment assemblies at 150 N with a frequency of 3 Hz. The amount of axial displacement, the Periotest values (PTVs), and the removal torque values(RTVs) were measured. Both a repeated measures analysis of variance and pattern analysis based on the linear mixed model were used for statistical analysis. Scanning electron microscopy (SEM) was used to evaluate the surface of the implant-abutment connection. The mean axial displacements after 1,000,000 cycles were 0.6 μm in the Ext group, 3.7 μm in the Int-1 group, and 9.0 μm in the Int-2 group. Pattern analysis revealed a breakpoint at 171 cycles. The Ext group showed no declining pattern, and the Int-1 group showed no declining pattern after the breakpoint (171 cycles). However, the Int-2 group experienced continuous axial displacement. After cyclic loading, the PTV decreased in the Int-2 group, and the RTV decreased in all groups. SEM imaging revealed surface wear in all groups. Axial displacement and surface wear occurred in all groups. The PTVs remained stable, but the RTVs decreased after cyclic loading. Based on linear mixed model analysis, the Ext and Int-1 groups' axial displacements plateaued after little cyclic loading. The Int-2 group's rate of axial displacement slowed after 100,000 cycles.

Comparison of saliva leakage amounts into internal implant cavities in three different internal implant-abutment interface configurations

Objectives: The aim of the present in vitro study was to compare the saliva leakage degrees of 3 different implant-abutment interface configurations. Materials and Methods : Implant systems with 3 different implant-abutment interfaces; internal perpendicular hexagon (IPH) (n=10), 11-degree angle morse-taper (IMT) (n=10), and 1.5-degree-angle cold welding type joints (ICW) (n=10) were selected. Totally 30 implant-abutment specimens were obtained by connecting the abutments to relevant implants. Initial (dry) weights (g) of the specimens were measured, recorded and all specimens were stored into artificial saliva. Subsequent weight measurements were performed at the end of 1 st day, 7 th day and 30 th day storage. Results : Significant weight differences were found both between experimental groups and between 4 weighting times within groups. Group ICW displayed significantly lowest weight difference values (lowest leakage) at all weighting times compared to groups IMT and IPH. Group IMT displayed higher but not significant weight difference values compared to group IPH at all weighting times. Conclusion : All tested systems displayed significant weight increases in each of the subsequent measurement times. Cold welding type implant-abutment configuration showed the lowest leakage values and was found the most suitable interface geometry for the minimization of leakage compared to other systems. Perpendicular hexagonal and morse taper type joint configurations displayed similar leakage values.

A Strain Gauge Analysis Comparing External and Internal Implant-Abutment Connections

This study compared the load transfer characteristics of a complete-arch restoration supported by 4 implants, with external and internal implant-abutment connections. Three loading positions were applied to the prostheses. Epoxy resin models were used to simulate bone. Two types of implants (ReplaceSelect Internal-Interface Tapered Implants and ReplaceSelect External-Interface Tapered Implants) were placed in the models. Complete-arch metal frameworks were constructed on the abutments. Artificial teeth were arranged on the framework, and the prosthesis was screwed onto the abutments. The strain gauges were bonded at the implant-abutment connection level of the specimens with 3 loading conditions (a) 4-point load, (b) 2-point anterior load, and (c) 2-point lateral load. The reading of strain values were recorded and compared. In all load conditions, there were strain differences between the external implant-abutment connection and internal implant-abutment connection. The internal implant-abutment connection resulted in lower stresses at the connection level. When loaded vertically, the internal implant-abutment connection produced less strain when compared with the external implant-abutment connection.

Influence of Placement Depth on Bone Remodeling Around Tapered Internal Connection Implant: A Clinical and Radiographic Study in Dogs

The aim of this study is to evaluate the influence of placement depth on bone remodeling around implants with two different types of tapered internal implant-abutment interface (IAI): tapped-in (TI) tapered internal IAI and screwed-in (SI) tapered internal IAI in dogs. The second, third, and fourth premolars and the first molar in mandibles of six beagle dogs were extracted. After 8 weeks, two SI implants and two TI implants were placed in one side of the mandible. There were four experimental groups: 1) SI placed crestally (SIC); 2) TI placed crestally (TIC); 3) SI placed 1.5 mm subcrestally (SIS); and 4) TI placed 1.5 mm subcrestally (TIS). Healing abutments were connected 12 weeks after implant surgery. Implants and teeth were brushed every second day during the healing period. Clinical and radiographic parameters were recorded at 4, 10, and 16 weeks after second-stage surgery. Differences between SI and TI implants inserted in the same vertical position were not significant for peri-implant probing depth (PD), clinical attachment level (CAL), or bone resorption (P >0.05). Subcrestal placement of both implants had greater PD and CAL compared to crestal groups. However, distance from IAI to the first bone-implant contact was lower in subcrestal groups compared to crestal groups (1.27 ± 0.42 mm for SIC versus 0.46 ± 0.26 mm for SIS, P <0.05; 1.36 ± 0.31 mm for TIC versus 0.78 ± 0.42 mm for TIS, P <0.05). Tapered internal IAI configuration had no significant effect on crestal bone resorption. Moreover, subcrestal placement of tapered internal IAI had a positive impact on crestal bone preservation around the cervix of the implant.

The Evolution of External and Internal Implant–Abutment Connections: A Review

A study of the implant–abutment connection is of great importance because it is the primary determinant of the strength and stability of an implant-supported restoration, which, in turn, determines the restoration’s prosthetic stability. Traditionally, Brånemark’s external hexagon has been used, but significant complications, such as abutment screw loosening, rotational misfit at the implant–abutment interface, and microbial penetration have led to modification of the external hexagon and the development of internal implant–abutment connections. In this review, we describe various implant–abutment connections that have evolved over time from the traditional external hexagon. &#x0D; How to cite this article: Alharissy M, Dayoub S. The Evolution of External and Internal Implant–Abutment Connections: A Review. Int Dent Res 2012;2:37-42.&#x0D; Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Evolution of External and Internal Implant to Abutment Connection

A study of the implant to abutment connection is of paramount importance as it is the primary determinant of the strength and stability of the implant supported restoration, which in turn determines the restoration’s prosthetic stability. Traditionally, the Branemark's external hexagon has been widely used but its significant complications like abutment screw loosening, rotational misfit at implant-abutment interface and microbial penetration have led to modification of the external hexagon and the development of the internal implant-abutment connections. This review describes the various implantabutment connections that have evolved overtime from the traditional external hexagon.

Photoelastic stress analysis of external versus internal implant-abutment connections

Common complications of implant restorations are abutment screw loosening and screw fracture. The geometry of the implant-abutment connection may affect stresses generated from loading, and these stresses may have a role in screw loosening or fracture. This study compared the load transfer characteristics of a complete-arch restoration supported by 4 implants with external and internal implant-abutment connections. Loads were applied to the prostheses in 3 positions. Two-dimensional photoelastic models were used to simulate bone. Two types of implants (ReplaceSelect Internal-Interface Tapered Implants and ReplaceSelect External-Interface Tapered Implants) were placed in the photoelastic models. Complete-arch metal frameworks were fabricated on the abutments. Artificial teeth were arranged on the framework, and the prosthesis was screwed onto the abutments. The specimens were analyzed at 2 levels (implant-abutment level and apical to the implant level) with 3 loading conditions (4-point load; 2-point anterior load; and 2-point lateral load). The numbers of fringe orders were recorded and compared. With the 4-point load, no stress differences occurred between the external-implant abutment connection and internal-implant abutment connection at the connection level and at the apical level. With the 2-point anterior load, the internal-implant abutment connection resulted in lower stresses at the connection level both in the loaded and non-loaded areas. With the 2-point lateral load, the internal-implant abutment connection resulted in lower stresses at the connection level at the non-loaded area. When loaded off-center, the internal-implant abutment connection produced less stress when compared with the external-implant abutment connection.

Bending moments of zirconia and titanium abutments with internal and external implant–abutment connections after aging and chewing simulation

To test the fracture load of zirconia abutments with different types of implant-abutment connections after chewing simulation and to compare their bending moments to internally connected identical titanium abutments. Forty-eight identical customized zirconia abutments with different implant-abutment connections were fabricated for four different test groups: one-piece internal implant-abutment connection (BL; Straumann Bonelevel), two-piece internal implant-abutment connection (RS; Nobel Biocare Replace Select), external implant-abutment connection (B; Brånemark MK III), two-piece internal implant-abutment connection (SP; Straumann Standard Plus). Twelve titanium abutments with one-piece internal implant-abutment connection (T; Straumann Bonelevel) served as control group. After aging by means of thermocycling (5-50°C, 120 s) and chewing simulation (1,200,000 cycles, 49 N load, 1.67 Hz), static load was applied at a 30° angle to the palatal surface until failure. Bending moments were calculated for comparison of the groups. Data were analyzed descriptively and by performing the Kruskal-Wallis test with Bonferroni correction. The mean bending moments of the abutments were 714.1 ± 184.9 N cm (T), 331.7 ± 57.8 N cm (BL), 429.7 ± 62.8 N cm (RS), 285.8 ± 64.4 N cm (B) and 379.9 ± 59.1 N cm (SP). The bending moments of control group T were significantly higher than those of all other groups. The values of group RS were significantly higher than those of group B but within the value range of groups SP and BL. The bending moments of the different tested types of zirconia abutments vary with different implant-abutment connections after chewing simulation. The use of a secondary metallic component might have a beneficial influence on the stability of zirconia abutments.