An interventional study of issue-level implant placed at crestal level (Klockner Essential Cone) and Bone-level implant placed 2 mm subcrestally with one-abutment-one-time protocol (Klockner Vega) in Partial Edentulism, Dental Implants and Alveolar Bone Loss, sponsored by Markel Diéguez-Pereira. Completed at 1 site in Spain. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-21.
Sponsored by Markel Diéguez-Pereira · Not applicable, Interventional, and Treatment
The goal of this clinical trial was to compare two ways of placing and restoring dental implants in adults missing one or more back teeth. The main question it aimed to answer was: does a bone-level implant placed 2 mm below the bone crest, with a final abutment that is never removed, preserve more of the bone around the implant than a tissue-level implant placed at the level of the bone crest?
Each implant was randomly assigned by coin toss to one of the two treatments. Researchers measured the bone level around the implants on dental X-rays at crown placement, 6 months after loading, and at a final visit 12 to 24 months after loading. They also measured two markers of inflammation (IL-1β and MMP-8) in the fluid around the implants 6 months after loading.
Design. Prospective, parallel-group randomized clinical trial conducted in private dental clinics in northern Spain. Randomization was performed at the implant level by simple coin toss at the surgical planning stage; patients receiving more than one implant could receive both configurations. There was no allocation concealment. Radiographic assessors and laboratory staff were blinded to group allocation.
Interventions. Tissue-level implants (Klockner Essential Cone, 1.5 mm machined transmucosal collar, conical connection) were placed with the treated surface at the crestal level. Bone-level implants (Klockner Vega, internal hexagon with a 10° conical interface and integrated platform switching) were placed 2 mm subcrestally. In the bone-level group, a definitive 2 mm transepithelial abutment was connected 2 months after surgery and was not removed thereafter (one-abutment-one-time concept). All implants were placed after mucoperiosteal flap elevation under antibiotic prophylaxis (2 g amoxicillin 1 h before surgery) and restored with screw-cement-retained monolithic zirconia single crowns.
Radiographic assessment. Standardized periapical radiographs were taken with the long-cone paralleling technique, using film holders and individualized silicone bite registrations. Marginal bone level was measured with ImageJ, calibrated on the known implant thread pitch, by two independent examiners.
Biomarker analysis. Peri-implant crevicular fluid was collected with sterile paper points (20 s), stored at -79 °C and analysed by ELISA for IL-1β and MMP-8.
Statistical analysis. Marginal bone level was analysed with linear mixed-effects models including random intercepts for patient and implant, to account for the clustering of implants within patients and for repeated measurements.
304 studies on the registry are indexed under Alveolar Bone Loss; 77 are open to participants now.
This study's enrollment of 30 is above the median of 25 across 261 interventional studies indexed under Alveolar Bone Loss.
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Exclusion Criteria:
Klockner Essential Cone tissue-level implants (1.5 mm machined transmucosal collar, conical connection) placed with the treated surface at the crestal level and restored with monolithic zirconia single crowns.
Device: issue-level implant placed at crestal level (Klockner Essential Cone)
Klockner Vega bone-level implants (internal hexagon with 10° conical interface and platform switching) placed 2 mm subcrestally. A definitive 2 mm transepithelial abutment was connected 2 months after surgery and was never removed (one-abutment-one-time protocol). Restored with monolithic zirconia single crowns.
Device: Bone-level implant placed 2 mm subcrestally with one-abutment-one-time protocol (Klockner Vega)
Tissue-level dental implant with a 1.5 mm machined transmucosal collar and conical connection, placed with the treated surface at the level of the bone crest after flap elevation.
Bone-level dental implant with an internal hexagonal connection, 10° conical interface and platform switching, placed 2 mm below the bone crest. A definitive 2 mm transepithelial abutment was connected 2 months after surgery and never removed.
Change From Baseline in Peri-Implant Marginal Bone Level at Final Follow-up
Vertical distance (mm) from the bone crest to the first implant thread, measured at the mesial and distal sites on standardized periapical radiographs (long-cone paralleling technique) with calibrated ImageJ software by two blinded examiners. Change is calculated as the baseline value minus the follow-up value; positive values indicate bone loss.
Time frame: Baseline (prosthesis delivery), 6 months after loading, and final follow-up (12 to 24 months after loading)
Interleukin-1β Concentration in Peri-Implant Crevicular Fluid
IL-1β concentration (pg/mL) in peri-implant crevicular fluid collected with sterile paper points (20 s) and analysed in duplicate by ELISA. Values below the detection limit (0.4 pg/mL) were set at half the detection limit for analysis.
Time frame: 12 months after loading
Matrix Metalloproteinase-8 Concentration in Peri-Implant Crevicular Fluid
MMP-8 concentration (ng/mL) in peri-implant crevicular fluid collected with sterile paper points (20 s) and analysed in duplicate by ELISA. Values below the detection limit (0.1 ng/mL) were set at half the detection limit for analysis.
Time frame: 12 months after loading
Ran from May 2022 to primary completion in Nov 2024, 30 months.
Of 160 non-industry interventional studies with no phase under Alveolar Bone Loss, half reached primary completion within 18 months of starting (the median), counting those still running; a quarter within 11 and three quarters within 30. This study's 30 months is above that.
Counting every sponsor, half of 160 studies reached it within 18 months; a quarter within 11 and three quarters within 30.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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