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Background:
Several in vitro and clinical studies have demonstrated that dental implant neck design, surface features and implant-abutment connection type influence the peri-implant tissue conditions (Aloy-Prosper et al. 2011). Comparative studies have shown that implant neck design and surface features can influence not only peri-implant bone remodeling but also clinical parameters such as bacterial plaque accumulation (Vroom et al. 2009), probing depth (Vroom et al. 2009; Martines et al. 2008), bleeding (Vroom et al. 2009; Chung et al. 2006), and keratinized mucosa thickness (Chung et al. 2006). Respect to implant-abutment connection type – external hexagon, internal hexagon or morse taper-, last decades switching platform concept has gained popularity. Main characteristic of the implant-abutment interface (IAI) in switching platform is the presence of a wider implant compared to the abutment, resulting in a horizontal mismatching (Canullo et al. 2012) that makes possible a new biological space is formed, establishing a mechanical barrier that serves as a defense mechanism, preventing the penetration of bacteria from the oral environment (Canullo et al. 2010). There is ample evidence that the design of the implant neck influences the amount of marginal peri-implant bone loss (Shin et al. 2006; Lee et al. 2007; McAllister 2007; Bratu et al. 2009; Nickenig et al. 2009) but there is a paucity of well-designed trials addressing the influence of the implant neck design on soft tissue parameters and clinical outcome variables (Hartog et al. 2011). At the implant-abutment interface (IAI) in two-piece implants, microbial migration to the inside of the implant–abutment assembly can occur (Assenza et al. 2012). Gramnegative anaerobia are implicated in peri-implant disease. Aggregatibacter actinomycetemcomitans (Aa) is present in the microbiota of peri-implantitis. The “red complex” of Socransky (Tannerea forsythia (Tf), Porphyromonas gingivalis (Pg) and Treponema denticola (Td)) are the most aggressive pathogens of the subgingival microbiota, involved with bone destruction.
Aim/Hypothesis:
The present study was designed to compare the influence of the implant neck design (machined surface without microthreads versus treated surface with microthreads) and implant-abutment connection (external-hexagon and internal Morse cone connection) with regard to peri-implant clinical and microbiological parameters before prosthetic restoration, and 6 and 12 months after prosthetic loading.
Material and Methods:
Study population A randomized, prospective clinical study was carried out in the Oral Surgery and Implantology Unit of a University Clinic, between January 2008 and October 2009. The following inclusion criteria were established: 1) patients with a completely edentulous arch requiring implant placement for: a) fixed prostheses (6-8 implants); b) bar overdentures (4 implants); or c) Locator® overdentures (2-4 implants); and 2) bone availability: a) minimum width 7 mm; and b) minimum height 6 mm. The exclusion criteria were: 1) systemic diseases contraindicating surgery; 2) a history of bisphosphonates use; 3) active infection at the implant site; 4) bone atrophy requiring regeneration; 5) systemic disorders (e.g., immune alterations) or drug treatments capable of affecting gingival health; 6) pregnant or nursing women; and 7) incomplete protocols. Signed informed consent to participation in the study was obtained in all cases. The study was approved by the local ethics committee, following the norms of the Declaration of Helsinki. The patients were homogeneously randomized to two groups using the SPSS statistical package (SPSS, Chicago, IL, USA): Group A – Osseous®: 9 patients treated with implants presenting a neck design without microthreads, with machined surface, external connection and without platform switching (Osseous®, Mozo-Grau, S.L., Valladolid, Spain). Group B – Inhex®: 9 patients treated with implants presenting a neck design with microthreads, treated surface, internal connection and platform switching (Inhex®, Mozo-Grau, S.L., Valladolid, Spain). Follow-up visits The control visits were made by a trained and calibrated clinician, at the following time-points: (0) with the healing abutment, immediately before obtaining the impressions; (1) one week after placement of the prosthesis; (2) 6 months after loading; and (3) 12 months after loading. At each time-point crevicular fluid samples were collected and all the below described clinical parameters were registered. Peri-implant crevicular fluid sampling Crevicular fluid volume was determined for all implants before recording the clinical parameters, in order not to interfere with the values obtained (Offenbacher et al. 1986). Crevicular fluid was collected by a single trained and calibrated operator, using sterile paper strips (Periopaper Strip®. Proflow Incorporated. New York, NY, USA). The technique was as follows: a) drying of the mouth with aspiration; b) isolation of the zone with cotton rolls; c) elimination of supragingival plaque from the sampling zone; d) gentle drying of the implant zone where the paper strip is to be placed; e) crevicular fluid sampling by placing the Periopaper Strip® in the peri-implant sulcus (30 seconds); f) placement of the samples between the Periotron® 8000 sensors (Proflow Incorporated. New York, NY, USA), to obtain the amount of crevicular fluid collected in Periotron units (PU); and g) sample placement in an Eppendorf tube with filter (Millipore, USA), followed by storage at -80ºC. Clinical parameters studied All measurements were obtained by the same trained and calibrated operator. The following parameters were evaluated: • Plaque index: The amount of plaque on each implant was determined based on the score developed by Mombelli et al. (Mombelli et al. 1987): (0) absence of plaque; (1) plaque not visible but removed with the periodontal probe; (2) plaque visible on the lower third of the implant; and (3) plaque visible on two-thirds of the implant. • Gingival retraction: This was defined as the abutment or implant neck surface exposed to the oral environment. Retraction was determined as being either present or absent, and where present was measured in millimeters at the point of maximum exposure, taking two points as reference: 1) the base of the prosthetic crown (cervical); and 2) the point of the gingival margin furthest from the previous point. The vertical distance between both points was determined. • Keratinized mucosa width: This was measured in millimeters from the mucogingival line to the peri-implant sulcus. • Probing depth: This parameter was recorded using a soft plastic periodontal probe with torque control to 0.25 N (Click-Probe®. Kerr. Bioggio, Switzerland). A registry of the peri-implant pockets of all the implants was obtained. Three vestibular and three lingual points to each implant were taken as references. The pocket depth values were classified as follows: ≤ 3 mm; > 3 mm and ≤ 6 mm; and > 6 mm. • Modified gingival index (GIm): Bleeding in response to probing was evaluated for each implant based on the score developed by Mombelli et al. (Mombelli et al. 1987): (0) absence of bleeding; (1) bleeding point; (2) bleeding line; and (3) profuse bleeding. • Mucositis: peri-implant mucositis was considered when there was reversible inflammation of the peri-implant mucosa, but no signs of loss of supporting bone existed. The most important diagnostic factor for this pathology was bleeding on probing with a maximum force of 0.25N (Lang et al. 2011). Microbiological analysis The supragingival plaque was removed, without penetrating into the peri-implant sulcus. The sampling zone was pressure air-dried previous a relative isolation with cottons. Sterile paper tips (Johnson & Johnson, Medical Inc., Arlington, TX, USA) were inserted to the bottom of the peri-implant sulcus 10 seconds. Were then placed in an eppendorf tube, with it liquid contents (guanidine thiocyanate 4 M and 2-mercaptoethanol) that fix the ARN of bacteria. For the microbiological analysis, the samples were sent to IAI Inc. Actinobacillus actinomycetemcomitans (Aa), Tannerela forsythia (Tf), Porphyromonas gingivalis (Pg) and Treponema denticola (Td) were evaluated by using the bacterial probe test IAI-PadoTest 4.5® (IAI Inc., IAI Institute, Zuchwill, Switzerland) -a system for the detection of periodontophatogens. The samples were mounted in nylon membranes and hybridized with specific P32 arrays directed against the sRNA ribosomal subunit (ssrRNAs) of every bacteria studied. A sample of every dental implant in each time-point was taken.
Results:
Patient data Eighteen totally edentulous patients were operated, representing a total of 141 dental implants: 69 Osseous® implants (group A) and 72 Inhex® implants (Group B) (Mozo-Grau S.L., Valladolid, Spain). Three patients were excluded: two due to failure to report to the control visits, and the other due to failure to report for placement of the prosthesis. Thus, 15 subjects (11 women and 4 men) were finally included in the study, aged between 44-77 years (mean 56.9 ± 7.8 years). There were 12 non-smokers, while three smoked fewer than 10 cigarettes/day. Eleven patients brushed their teeth 1-2 times/day, and four patients, 3 or more times/day. Eight patients received Osseous® implants and the remaining 7 received Inhex® implants. Five patients underwent rehabilitation of the upper maxilla, one patient the lower one and the remaining 9 underwent rehabilitation of both dental arches. Forty-seven percent of the total 120 implants corresponded to Group A (Osseous®) and 53% to Group B (Inhex®). Two implants failed, one in the Group A and another one in the Group B. Globally, 98.6% implants survived and 97.2% ended successfully. Four implants did not meet the success criteria of Buser (Buser et al 1999); 2 because of mobility (one Inhex® and one Osseous®) and 2 for continuous radiolucency but not mobility (one Inhex® and one Osseous®). Both mobile implants had been rehabilitated by overdenture with Locators®. Implant mobility detection was possible because implants were not stented by the prosthesis. Implants were examined about mobility if subjective symptoms of pain, pus, or radiological signs of continuous radiolucency were present. On separately evaluating the two patient groups, 98.6% implants survived and 97,1% were successful for the Osseous® group and 98.6% implants survived and 97.2% were successful for the Inhex® group. There were no significant differences in crevicular fluid volume, gingival retraction, probing depth or mucositis at any time during the study. Plaque index and the modified gingival index exposed differences at the first control time-point between the two groups, with no significant differences at the rest of the time-points. There was a greater presence of keratinized mucosa in the Osseous® group than in the Inhex® group. Bacterial load of Pg, Td and TBL was greater in Osseous® group than in Inhex® group. A significant temporal relationship of Pg respect to presence of mucositis in the Osseous ® group was observed.
Conclusions and clinical implications:
After 12 months of follow-up, the clinical values obtained in both groups (Osseous® and Inhex®) were indicative of good peri-implant health. An increased width of keratinized mucosa was observed with the Osseous® implants versus the Inhex® implants, though in both cases the results were compatible with good peri-implant health. Bacterial loads of Pg, Td and TBL was greater in Osseous® group than Inhex® group.
Background:
Several in vitro and clinical studies have demonstrated that dental implant neck design, surface features and implant-abutment connection type influence the peri-implant tissue conditions (Aloy-Prosper et al. 2011). Comparative studies have shown that implant neck design and surface features can influence not only peri-implant bone remodeling but also clinical parameters such as bacterial plaque accumulation (Vroom et al. 2009), probing depth (Vroom et al. 2009; Martines et al. 2008), bleeding (Vroom et al. 2009; Chung et al. 2006), and keratinized mucosa thickness (Chung et al. 2006). Respect to implant-abutment connection type – external hexagon, internal hexagon or morse taper-, last decades switching platform concept has gained popularity. Main characteristic of the implant-abutment interface (IAI) in switching platform is the presence of a wider implant compared to the abutment, resulting in a horizontal mismatching (Canullo et al. 2012) that makes possible a new biological space is formed, establishing a mechanical barrier that serves as a defense mechanism, preventing the penetration of bacteria from the oral environment (Canullo et al. 2010). There is ample evidence that the design of the implant neck influences the amount of marginal peri-implant bone loss (Shin et al. 2006; Lee et al. 2007; McAllister 2007; Bratu et al. 2009; Nickenig et al. 2009) but there is a paucity of well-designed trials addressing the influence of the implant neck design on soft tissue parameters and clinical outcome variables (Hartog et al. 2011). At the implant-abutment interface (IAI) in two-piece implants, microbial migration to the inside of the implant–abutment assembly can occur (Assenza et al. 2012). Gramnegative anaerobia are implicated in peri-implant disease. Aggregatibacter actinomycetemcomitans (Aa) is present in the microbiota of peri-implantitis. The “red complex” of Socransky (Tannerea forsythia (Tf), Porphyromonas gingivalis (Pg) and Treponema denticola (Td)) are the most aggressive pathogens of the subgingival microbiota, involved with bone destruction.
Aim/Hypothesis:
The present study was designed to compare the influence of the implant neck design (machined surface without microthreads versus treated surface with microthreads) and implant-abutment connection (external-hexagon and internal Morse cone connection) with regard to peri-implant clinical and microbiological parameters before prosthetic restoration, and 6 and 12 months after prosthetic loading.
Material and Methods:
Study population A randomized, prospective clinical study was carried out in the Oral Surgery and Implantology Unit of a University Clinic, between January 2008 and October 2009. The following inclusion criteria were established: 1) patients with a completely edentulous arch requiring implant placement for: a) fixed prostheses (6-8 implants); b) bar overdentures (4 implants); or c) Locator® overdentures (2-4 implants); and 2) bone availability: a) minimum width 7 mm; and b) minimum height 6 mm. The exclusion criteria were: 1) systemic diseases contraindicating surgery; 2) a history of bisphosphonates use; 3) active infection at the implant site; 4) bone atrophy requiring regeneration; 5) systemic disorders (e.g., immune alterations) or drug treatments capable of affecting gingival health; 6) pregnant or nursing women; and 7) incomplete protocols. Signed informed consent to participation in the study was obtained in all cases. The study was approved by the local ethics committee, following the norms of the Declaration of Helsinki. The patients were homogeneously randomized to two groups using the SPSS statistical package (SPSS, Chicago, IL, USA): Group A – Osseous®: 9 patients treated with implants presenting a neck design without microthreads, with machined surface, external connection and without platform switching (Osseous®, Mozo-Grau, S.L., Valladolid, Spain). Group B – Inhex®: 9 patients treated with implants presenting a neck design with microthreads, treated surface, internal connection and platform switching (Inhex®, Mozo-Grau, S.L., Valladolid, Spain). Follow-up visits The control visits were made by a trained and calibrated clinician, at the following time-points: (0) with the healing abutment, immediately before obtaining the impressions; (1) one week after placement of the prosthesis; (2) 6 months after loading; and (3) 12 months after loading. At each time-point crevicular fluid samples were collected and all the below described clinical parameters were registered. Peri-implant crevicular fluid sampling Crevicular fluid volume was determined for all implants before recording the clinical parameters, in order not to interfere with the values obtained (Offenbacher et al. 1986). Crevicular fluid was collected by a single trained and calibrated operator, using sterile paper strips (Periopaper Strip®. Proflow Incorporated. New York, NY, USA). The technique was as follows: a) drying of the mouth with aspiration; b) isolation of the zone with cotton rolls; c) elimination of supragingival plaque from the sampling zone; d) gentle drying of the implant zone where the paper strip is to be placed; e) crevicular fluid sampling by placing the Periopaper Strip® in the peri-implant sulcus (30 seconds); f) placement of the samples between the Periotron® 8000 sensors (Proflow Incorporated. New York, NY, USA), to obtain the amount of crevicular fluid collected in Periotron units (PU); and g) sample placement in an Eppendorf tube with filter (Millipore, USA), followed by storage at -80ºC. Clinical parameters studied All measurements were obtained by the same trained and calibrated operator. The following parameters were evaluated: • Plaque index: The amount of plaque on each implant was determined based on the score developed by Mombelli et al. (Mombelli et al. 1987): (0) absence of plaque; (1) plaque not visible but removed with the periodontal probe; (2) plaque visible on the lower third of the implant; and (3) plaque visible on two-thirds of the implant. • Gingival retraction: This was defined as the abutment or implant neck surface exposed to the oral environment. Retraction was determined as being either present or absent, and where present was measured in millimeters at the point of maximum exposure, taking two points as reference: 1) the base of the prosthetic crown (cervical); and 2) the point of the gingival margin furthest from the previous point. The vertical distance between both points was determined. • Keratinized mucosa width: This was measured in millimeters from the mucogingival line to the peri-implant sulcus. • Probing depth: This parameter was recorded using a soft plastic periodontal probe with torque control to 0.25 N (Click-Probe®. Kerr. Bioggio, Switzerland). A registry of the peri-implant pockets of all the implants was obtained. Three vestibular and three lingual points to each implant were taken as references. The pocket depth values were classified as follows: ≤ 3 mm; > 3 mm and ≤ 6 mm; and > 6 mm. • Modified gingival index (GIm): Bleeding in response to probing was evaluated for each implant based on the score developed by Mombelli et al. (Mombelli et al. 1987): (0) absence of bleeding; (1) bleeding point; (2) bleeding line; and (3) profuse bleeding. • Mucositis: peri-implant mucositis was considered when there was reversible inflammation of the peri-implant mucosa, but no signs of loss of supporting bone existed. The most important diagnostic factor for this pathology was bleeding on probing with a maximum force of 0.25N (Lang et al. 2011). Microbiological analysis The supragingival plaque was removed, without penetrating into the peri-implant sulcus. The sampling zone was pressure air-dried previous a relative isolation with cottons. Sterile paper tips (Johnson & Johnson, Medical Inc., Arlington, TX, USA) were inserted to the bottom of the peri-implant sulcus 10 seconds. Were then placed in an eppendorf tube, with it liquid contents (guanidine thiocyanate 4 M and 2-mercaptoethanol) that fix the ARN of bacteria. For the microbiological analysis, the samples were sent to IAI Inc. Actinobacillus actinomycetemcomitans (Aa), Tannerela forsythia (Tf), Porphyromonas gingivalis (Pg) and Treponema denticola (Td) were evaluated by using the bacterial probe test IAI-PadoTest 4.5® (IAI Inc., IAI Institute, Zuchwill, Switzerland) -a system for the detection of periodontophatogens. The samples were mounted in nylon membranes and hybridized with specific P32 arrays directed against the sRNA ribosomal subunit (ssrRNAs) of every bacteria studied. A sample of every dental implant in each time-point was taken.
Results:
Patient data Eighteen totally edentulous patients were operated, representing a total of 141 dental implants: 69 Osseous® implants (group A) and 72 Inhex® implants (Group B) (Mozo-Grau S.L., Valladolid, Spain). Three patients were excluded: two due to failure to report to the control visits, and the other due to failure to report for placement of the prosthesis. Thus, 15 subjects (11 women and 4 men) were finally included in the study, aged between 44-77 years (mean 56.9 ± 7.8 years). There were 12 non-smokers, while three smoked fewer than 10 cigarettes/day. Eleven patients brushed their teeth 1-2 times/day, and four patients, 3 or more times/day. Eight patients received Osseous® implants and the remaining 7 received Inhex® implants. Five patients underwent rehabilitation of the upper maxilla, one patient the lower one and the remaining 9 underwent rehabilitation of both dental arches. Forty-seven percent of the total 120 implants corresponded to Group A (Osseous®) and 53% to Group B (Inhex®). Two implants failed, one in the Group A and another one in the Group B. Globally, 98.6% implants survived and 97.2% ended successfully. Four implants did not meet the success criteria of Buser (Buser et al 1999); 2 because of mobility (one Inhex® and one Osseous®) and 2 for continuous radiolucency but not mobility (one Inhex® and one Osseous®). Both mobile implants had been rehabilitated by overdenture with Locators®. Implant mobility detection was possible because implants were not stented by the prosthesis. Implants were examined about mobility if subjective symptoms of pain, pus, or radiological signs of continuous radiolucency were present. On separately evaluating the two patient groups, 98.6% implants survived and 97,1% were successful for the Osseous® group and 98.6% implants survived and 97.2% were successful for the Inhex® group. There were no significant differences in crevicular fluid volume, gingival retraction, probing depth or mucositis at any time during the study. Plaque index and the modified gingival index exposed differences at the first control time-point between the two groups, with no significant differences at the rest of the time-points. There was a greater presence of keratinized mucosa in the Osseous® group than in the Inhex® group. Bacterial load of Pg, Td and TBL was greater in Osseous® group than in Inhex® group. A significant temporal relationship of Pg respect to presence of mucositis in the Osseous ® group was observed.
Conclusions and clinical implications:
After 12 months of follow-up, the clinical values obtained in both groups (Osseous® and Inhex®) were indicative of good peri-implant health. An increased width of keratinized mucosa was observed with the Osseous® implants versus the Inhex® implants, though in both cases the results were compatible with good peri-implant health. Bacterial loads of Pg, Td and TBL was greater in Osseous® group than Inhex® group.
Background:
Several in vitro and clinical studies have demonstrated that dental implant neck design, surface features and implant-abutment connection type influence the peri-implant tissue conditions (Aloy-Prosper et al. 2011). Comparative studies have shown that implant neck design and surface features can influence not only peri-implant bone remodeling but also clinical parameters such as bacterial plaque accumulation (Vroom et al. 2009), probing depth (Vroom et al. 2009; Martines et al. 2008), bleeding (Vroom et al. 2009; Chung et al. 2006), and keratinized mucosa thickness (Chung et al. 2006). Respect to implant-abutment connection type – external hexagon, internal hexagon or morse taper-, last decades switching platform concept has gained popularity. Main characteristic of the implant-abutment interface (IAI) in switching platform is the presence of a wider implant compared to the abutment, resulting in a horizontal mismatching (Canullo et al. 2012) that makes possible a new biological space is formed, establishing a mechanical barrier that serves as a defense mechanism, preventing the penetration of bacteria from the oral environment (Canullo et al. 2010). There is ample evidence that the design of the implant neck influences the amount of marginal peri-implant bone loss (Shin et al. 2006; Lee et al. 2007; McAllister 2007; Bratu et al. 2009; Nickenig et al. 2009) but there is a paucity of well-designed trials addressing the influence of the implant neck design on soft tissue parameters and clinical outcome variables (Hartog et al. 2011). At the implant-abutment interface (IAI) in two-piece implants, microbial migration to the inside of the implant–abutment assembly can occur (Assenza et al. 2012). Gramnegative anaerobia are implicated in peri-implant disease. Aggregatibacter actinomycetemcomitans (Aa) is present in the microbiota of peri-implantitis. The “red complex” of Socransky (Tannerea forsythia (Tf), Porphyromonas gingivalis (Pg) and Treponema denticola (Td)) are the most aggressive pathogens of the subgingival microbiota, involved with bone destruction.
Aim/Hypothesis:
The present study was designed to compare the influence of the implant neck design (machined surface without microthreads versus treated surface with microthreads) and implant-abutment connection (external-hexagon and internal Morse cone connection) with regard to peri-implant clinical and microbiological parameters before prosthetic restoration, and 6 and 12 months after prosthetic loading.
Material and Methods:
Study population A randomized, prospective clinical study was carried out in the Oral Surgery and Implantology Unit of a University Clinic, between January 2008 and October 2009. The following inclusion criteria were established: 1) patients with a completely edentulous arch requiring implant placement for: a) fixed prostheses (6-8 implants); b) bar overdentures (4 implants); or c) Locator® overdentures (2-4 implants); and 2) bone availability: a) minimum width 7 mm; and b) minimum height 6 mm. The exclusion criteria were: 1) systemic diseases contraindicating surgery; 2) a history of bisphosphonates use; 3) active infection at the implant site; 4) bone atrophy requiring regeneration; 5) systemic disorders (e.g., immune alterations) or drug treatments capable of affecting gingival health; 6) pregnant or nursing women; and 7) incomplete protocols. Signed informed consent to participation in the study was obtained in all cases. The study was approved by the local ethics committee, following the norms of the Declaration of Helsinki. The patients were homogeneously randomized to two groups using the SPSS statistical package (SPSS, Chicago, IL, USA): Group A – Osseous®: 9 patients treated with implants presenting a neck design without microthreads, with machined surface, external connection and without platform switching (Osseous®, Mozo-Grau, S.L., Valladolid, Spain). Group B – Inhex®: 9 patients treated with implants presenting a neck design with microthreads, treated surface, internal connection and platform switching (Inhex®, Mozo-Grau, S.L., Valladolid, Spain). Follow-up visits The control visits were made by a trained and calibrated clinician, at the following time-points: (0) with the healing abutment, immediately before obtaining the impressions; (1) one week after placement of the prosthesis; (2) 6 months after loading; and (3) 12 months after loading. At each time-point crevicular fluid samples were collected and all the below described clinical parameters were registered. Peri-implant crevicular fluid sampling Crevicular fluid volume was determined for all implants before recording the clinical parameters, in order not to interfere with the values obtained (Offenbacher et al. 1986). Crevicular fluid was collected by a single trained and calibrated operator, using sterile paper strips (Periopaper Strip®. Proflow Incorporated. New York, NY, USA). The technique was as follows: a) drying of the mouth with aspiration; b) isolation of the zone with cotton rolls; c) elimination of supragingival plaque from the sampling zone; d) gentle drying of the implant zone where the paper strip is to be placed; e) crevicular fluid sampling by placing the Periopaper Strip® in the peri-implant sulcus (30 seconds); f) placement of the samples between the Periotron® 8000 sensors (Proflow Incorporated. New York, NY, USA), to obtain the amount of crevicular fluid collected in Periotron units (PU); and g) sample placement in an Eppendorf tube with filter (Millipore, USA), followed by storage at -80ºC. Clinical parameters studied All measurements were obtained by the same trained and calibrated operator. The following parameters were evaluated: • Plaque index: The amount of plaque on each implant was determined based on the score developed by Mombelli et al. (Mombelli et al. 1987): (0) absence of plaque; (1) plaque not visible but removed with the periodontal probe; (2) plaque visible on the lower third of the implant; and (3) plaque visible on two-thirds of the implant. • Gingival retraction: This was defined as the abutment or implant neck surface exposed to the oral environment. Retraction was determined as being either present or absent, and where present was measured in millimeters at the point of maximum exposure, taking two points as reference: 1) the base of the prosthetic crown (cervical); and 2) the point of the gingival margin furthest from the previous point. The vertical distance between both points was determined. • Keratinized mucosa width: This was measured in millimeters from the mucogingival line to the peri-implant sulcus. • Probing depth: This parameter was recorded using a soft plastic periodontal probe with torque control to 0.25 N (Click-Probe®. Kerr. Bioggio, Switzerland). A registry of the peri-implant pockets of all the implants was obtained. Three vestibular and three lingual points to each implant were taken as references. The pocket depth values were classified as follows: ≤ 3 mm; > 3 mm and ≤ 6 mm; and > 6 mm. • Modified gingival index (GIm): Bleeding in response to probing was evaluated for each implant based on the score developed by Mombelli et al. (Mombelli et al. 1987): (0) absence of bleeding; (1) bleeding point; (2) bleeding line; and (3) profuse bleeding. • Mucositis: peri-implant mucositis was considered when there was reversible inflammation of the peri-implant mucosa, but no signs of loss of supporting bone existed. The most important diagnostic factor for this pathology was bleeding on probing with a maximum force of 0.25N (Lang et al. 2011). Microbiological analysis The supragingival plaque was removed, without penetrating into the peri-implant sulcus. The sampling zone was pressure air-dried previous a relative isolation with cottons. Sterile paper tips (Johnson & Johnson, Medical Inc., Arlington, TX, USA) were inserted to the bottom of the peri-implant sulcus 10 seconds. Were then placed in an eppendorf tube, with it liquid contents (guanidine thiocyanate 4 M and 2-mercaptoethanol) that fix the ARN of bacteria. For the microbiological analysis, the samples were sent to IAI Inc. Actinobacillus actinomycetemcomitans (Aa), Tannerela forsythia (Tf), Porphyromonas gingivalis (Pg) and Treponema denticola (Td) were evaluated by using the bacterial probe test IAI-PadoTest 4.5® (IAI Inc., IAI Institute, Zuchwill, Switzerland) -a system for the detection of periodontophatogens. The samples were mounted in nylon membranes and hybridized with specific P32 arrays directed against the sRNA ribosomal subunit (ssrRNAs) of every bacteria studied. A sample of every dental implant in each time-point was taken.
Results:
Patient data Eighteen totally edentulous patients were operated, representing a total of 141 dental implants: 69 Osseous® implants (group A) and 72 Inhex® implants (Group B) (Mozo-Grau S.L., Valladolid, Spain). Three patients were excluded: two due to failure to report to the control visits, and the other due to failure to report for placement of the prosthesis. Thus, 15 subjects (11 women and 4 men) were finally included in the study, aged between 44-77 years (mean 56.9 ± 7.8 years). There were 12 non-smokers, while three smoked fewer than 10 cigarettes/day. Eleven patients brushed their teeth 1-2 times/day, and four patients, 3 or more times/day. Eight patients received Osseous® implants and the remaining 7 received Inhex® implants. Five patients underwent rehabilitation of the upper maxilla, one patient the lower one and the remaining 9 underwent rehabilitation of both dental arches. Forty-seven percent of the total 120 implants corresponded to Group A (Osseous®) and 53% to Group B (Inhex®). Two implants failed, one in the Group A and another one in the Group B. Globally, 98.6% implants survived and 97.2% ended successfully. Four implants did not meet the success criteria of Buser (Buser et al 1999); 2 because of mobility (one Inhex® and one Osseous®) and 2 for continuous radiolucency but not mobility (one Inhex® and one Osseous®). Both mobile implants had been rehabilitated by overdenture with Locators®. Implant mobility detection was possible because implants were not stented by the prosthesis. Implants were examined about mobility if subjective symptoms of pain, pus, or radiological signs of continuous radiolucency were present. On separately evaluating the two patient groups, 98.6% implants survived and 97,1% were successful for the Osseous® group and 98.6% implants survived and 97.2% were successful for the Inhex® group. There were no significant differences in crevicular fluid volume, gingival retraction, probing depth or mucositis at any time during the study. Plaque index and the modified gingival index exposed differences at the first control time-point between the two groups, with no significant differences at the rest of the time-points. There was a greater presence of keratinized mucosa in the Osseous® group than in the Inhex® group. Bacterial load of Pg, Td and TBL was greater in Osseous® group than in Inhex® group. A significant temporal relationship of Pg respect to presence of mucositis in the Osseous ® group was observed.
Conclusions and clinical implications:
After 12 months of follow-up, the clinical values obtained in both groups (Osseous® and Inhex®) were indicative of good peri-implant health. An increased width of keratinized mucosa was observed with the Osseous® implants versus the Inhex® implants, though in both cases the results were compatible with good peri-implant health. Bacterial loads of Pg, Td and TBL was greater in Osseous® group than Inhex® group.
Background:
Several in vitro and clinical studies have demonstrated that dental implant neck design, surface features and implant-abutment connection type influence the peri-implant tissue conditions (Aloy-Prosper et al. 2011). Comparative studies have shown that implant neck design and surface features can influence not only peri-implant bone remodeling but also clinical parameters such as bacterial plaque accumulation (Vroom et al. 2009), probing depth (Vroom et al. 2009; Martines et al. 2008), bleeding (Vroom et al. 2009; Chung et al. 2006), and keratinized mucosa thickness (Chung et al. 2006). Respect to implant-abutment connection type – external hexagon, internal hexagon or morse taper-, last decades switching platform concept has gained popularity. Main characteristic of the implant-abutment interface (IAI) in switching platform is the presence of a wider implant compared to the abutment, resulting in a horizontal mismatching (Canullo et al. 2012) that makes possible a new biological space is formed, establishing a mechanical barrier that serves as a defense mechanism, preventing the penetration of bacteria from the oral environment (Canullo et al. 2010). There is ample evidence that the design of the implant neck influences the amount of marginal peri-implant bone loss (Shin et al. 2006; Lee et al. 2007; McAllister 2007; Bratu et al. 2009; Nickenig et al. 2009) but there is a paucity of well-designed trials addressing the influence of the implant neck design on soft tissue parameters and clinical outcome variables (Hartog et al. 2011). At the implant-abutment interface (IAI) in two-piece implants, microbial migration to the inside of the implant–abutment assembly can occur (Assenza et al. 2012). Gramnegative anaerobia are implicated in peri-implant disease. Aggregatibacter actinomycetemcomitans (Aa) is present in the microbiota of peri-implantitis. The “red complex” of Socransky (Tannerea forsythia (Tf), Porphyromonas gingivalis (Pg) and Treponema denticola (Td)) are the most aggressive pathogens of the subgingival microbiota, involved with bone destruction.
Aim/Hypothesis:
The present study was designed to compare the influence of the implant neck design (machined surface without microthreads versus treated surface with microthreads) and implant-abutment connection (external-hexagon and internal Morse cone connection) with regard to peri-implant clinical and microbiological parameters before prosthetic restoration, and 6 and 12 months after prosthetic loading.
Material and Methods:
Study population A randomized, prospective clinical study was carried out in the Oral Surgery and Implantology Unit of a University Clinic, between January 2008 and October 2009. The following inclusion criteria were established: 1) patients with a completely edentulous arch requiring implant placement for: a) fixed prostheses (6-8 implants); b) bar overdentures (4 implants); or c) Locator® overdentures (2-4 implants); and 2) bone availability: a) minimum width 7 mm; and b) minimum height 6 mm. The exclusion criteria were: 1) systemic diseases contraindicating surgery; 2) a history of bisphosphonates use; 3) active infection at the implant site; 4) bone atrophy requiring regeneration; 5) systemic disorders (e.g., immune alterations) or drug treatments capable of affecting gingival health; 6) pregnant or nursing women; and 7) incomplete protocols. Signed informed consent to participation in the study was obtained in all cases. The study was approved by the local ethics committee, following the norms of the Declaration of Helsinki. The patients were homogeneously randomized to two groups using the SPSS statistical package (SPSS, Chicago, IL, USA): Group A – Osseous®: 9 patients treated with implants presenting a neck design without microthreads, with machined surface, external connection and without platform switching (Osseous®, Mozo-Grau, S.L., Valladolid, Spain). Group B – Inhex®: 9 patients treated with implants presenting a neck design with microthreads, treated surface, internal connection and platform switching (Inhex®, Mozo-Grau, S.L., Valladolid, Spain). Follow-up visits The control visits were made by a trained and calibrated clinician, at the following time-points: (0) with the healing abutment, immediately before obtaining the impressions; (1) one week after placement of the prosthesis; (2) 6 months after loading; and (3) 12 months after loading. At each time-point crevicular fluid samples were collected and all the below described clinical parameters were registered. Peri-implant crevicular fluid sampling Crevicular fluid volume was determined for all implants before recording the clinical parameters, in order not to interfere with the values obtained (Offenbacher et al. 1986). Crevicular fluid was collected by a single trained and calibrated operator, using sterile paper strips (Periopaper Strip®. Proflow Incorporated. New York, NY, USA). The technique was as follows: a) drying of the mouth with aspiration; b) isolation of the zone with cotton rolls; c) elimination of supragingival plaque from the sampling zone; d) gentle drying of the implant zone where the paper strip is to be placed; e) crevicular fluid sampling by placing the Periopaper Strip® in the peri-implant sulcus (30 seconds); f) placement of the samples between the Periotron® 8000 sensors (Proflow Incorporated. New York, NY, USA), to obtain the amount of crevicular fluid collected in Periotron units (PU); and g) sample placement in an Eppendorf tube with filter (Millipore, USA), followed by storage at -80ºC. Clinical parameters studied All measurements were obtained by the same trained and calibrated operator. The following parameters were evaluated: • Plaque index: The amount of plaque on each implant was determined based on the score developed by Mombelli et al. (Mombelli et al. 1987): (0) absence of plaque; (1) plaque not visible but removed with the periodontal probe; (2) plaque visible on the lower third of the implant; and (3) plaque visible on two-thirds of the implant. • Gingival retraction: This was defined as the abutment or implant neck surface exposed to the oral environment. Retraction was determined as being either present or absent, and where present was measured in millimeters at the point of maximum exposure, taking two points as reference: 1) the base of the prosthetic crown (cervical); and 2) the point of the gingival margin furthest from the previous point. The vertical distance between both points was determined. • Keratinized mucosa width: This was measured in millimeters from the mucogingival line to the peri-implant sulcus. • Probing depth: This parameter was recorded using a soft plastic periodontal probe with torque control to 0.25 N (Click-Probe®. Kerr. Bioggio, Switzerland). A registry of the peri-implant pockets of all the implants was obtained. Three vestibular and three lingual points to each implant were taken as references. The pocket depth values were classified as follows: ≤ 3 mm; > 3 mm and ≤ 6 mm; and > 6 mm. • Modified gingival index (GIm): Bleeding in response to probing was evaluated for each implant based on the score developed by Mombelli et al. (Mombelli et al. 1987): (0) absence of bleeding; (1) bleeding point; (2) bleeding line; and (3) profuse bleeding. • Mucositis: peri-implant mucositis was considered when there was reversible inflammation of the peri-implant mucosa, but no signs of loss of supporting bone existed. The most important diagnostic factor for this pathology was bleeding on probing with a maximum force of 0.25N (Lang et al. 2011). Microbiological analysis The supragingival plaque was removed, without penetrating into the peri-implant sulcus. The sampling zone was pressure air-dried previous a relative isolation with cottons. Sterile paper tips (Johnson & Johnson, Medical Inc., Arlington, TX, USA) were inserted to the bottom of the peri-implant sulcus 10 seconds. Were then placed in an eppendorf tube, with it liquid contents (guanidine thiocyanate 4 M and 2-mercaptoethanol) that fix the ARN of bacteria. For the microbiological analysis, the samples were sent to IAI Inc. Actinobacillus actinomycetemcomitans (Aa), Tannerela forsythia (Tf), Porphyromonas gingivalis (Pg) and Treponema denticola (Td) were evaluated by using the bacterial probe test IAI-PadoTest 4.5® (IAI Inc., IAI Institute, Zuchwill, Switzerland) -a system for the detection of periodontophatogens. The samples were mounted in nylon membranes and hybridized with specific P32 arrays directed against the sRNA ribosomal subunit (ssrRNAs) of every bacteria studied. A sample of every dental implant in each time-point was taken.
Results:
Patient data Eighteen totally edentulous patients were operated, representing a total of 141 dental implants: 69 Osseous® implants (group A) and 72 Inhex® implants (Group B) (Mozo-Grau S.L., Valladolid, Spain). Three patients were excluded: two due to failure to report to the control visits, and the other due to failure to report for placement of the prosthesis. Thus, 15 subjects (11 women and 4 men) were finally included in the study, aged between 44-77 years (mean 56.9 ± 7.8 years). There were 12 non-smokers, while three smoked fewer than 10 cigarettes/day. Eleven patients brushed their teeth 1-2 times/day, and four patients, 3 or more times/day. Eight patients received Osseous® implants and the remaining 7 received Inhex® implants. Five patients underwent rehabilitation of the upper maxilla, one patient the lower one and the remaining 9 underwent rehabilitation of both dental arches. Forty-seven percent of the total 120 implants corresponded to Group A (Osseous®) and 53% to Group B (Inhex®). Two implants failed, one in the Group A and another one in the Group B. Globally, 98.6% implants survived and 97.2% ended successfully. Four implants did not meet the success criteria of Buser (Buser et al 1999); 2 because of mobility (one Inhex® and one Osseous®) and 2 for continuous radiolucency but not mobility (one Inhex® and one Osseous®). Both mobile implants had been rehabilitated by overdenture with Locators®. Implant mobility detection was possible because implants were not stented by the prosthesis. Implants were examined about mobility if subjective symptoms of pain, pus, or radiological signs of continuous radiolucency were present. On separately evaluating the two patient groups, 98.6% implants survived and 97,1% were successful for the Osseous® group and 98.6% implants survived and 97.2% were successful for the Inhex® group. There were no significant differences in crevicular fluid volume, gingival retraction, probing depth or mucositis at any time during the study. Plaque index and the modified gingival index exposed differences at the first control time-point between the two groups, with no significant differences at the rest of the time-points. There was a greater presence of keratinized mucosa in the Osseous® group than in the Inhex® group. Bacterial load of Pg, Td and TBL was greater in Osseous® group than in Inhex® group. A significant temporal relationship of Pg respect to presence of mucositis in the Osseous ® group was observed.
Conclusions and clinical implications:
After 12 months of follow-up, the clinical values obtained in both groups (Osseous® and Inhex®) were indicative of good peri-implant health. An increased width of keratinized mucosa was observed with the Osseous® implants versus the Inhex® implants, though in both cases the results were compatible with good peri-implant health. Bacterial loads of Pg, Td and TBL was greater in Osseous® group than Inhex® group.