An interventional study of Short Neck Implant - Crestal Placement and Standard Neck Implant - 1 mm Subcrestal Placement in Edentulism, Dental Implantation, Endosseous and Marginal Bone Loss, sponsored by ARDEC Academy. Active, not recruiting at 1 site in Cuba. Open to participants aged 21 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-08-06.
Sponsored by ARDEC Academy · Not applicable, Interventional, and Treatment
The goal of this clinical trial is to understand how different implant neck designs and placement depths affect the surrounding bone and peri-implant tissue (the tissue around a dental implant) in adults who need implants in the back areas of the mouth (molars and premolars). The main questions it aims to answer are:
Does placing implants deeper under the bone crest (subcrestally) help preserve more bone and peri-implant tissue over time? Do implants with longer, conical necks and micro-threaded surfaces result in more stable peri-implant tissue than implants with shorter necks? Researchers will compare three types of one-piece dental implants with different neck heights (short, standard, and long), placed at different depths in the jawbone, to determine which combination better maintains bone and peri-implant tissue levels.
Participants will:
Receive two dental implants in the posterior upper or lower jaw Be randomly assigned to one of three groups depending on implant neck design and placement depth Undergo implant surgery using a digital workflow, with healing over three months Be rehabilitated with custom zirconia bridges Return for regular clinical and imaging checkups over a period of at least 3 years This study aims to generate evidence that helps clinicians choose implant designs and techniques that promote long-term peri-implant tissue health.
This randomized controlled clinical trial investigates the impact of different transmucosal neck configurations and vertical placement levels of one-piece dental implants on peri-implant hard and soft tissue stability over time. The trial specifically focuses on the PRAMA implant system (Sweden \& Martina, Italy), which incorporates a ZirTi surface and a convergent neck design with an Ultrathin Threaded Microsurface (UTM). These implants are designed to optimize tissue integration and minimize marginal bone loss.
The study explores how subcrestal versus crestal placement of the rough-to-smooth transition, combined with variable neck lengths, influences peri-implant tissue outcomes under functional loading in posterior edentulous sites. Three types of PRAMA implants will be compared:
Short neck (1.8 mm total length with hyperbolic convergent shape)
Standard neck (0.8 mm cylindrical plus 2.0 mm convergent portion)
Long neck (0.8 mm cylindrical plus 3.0 mm convergent portion)
Each patient will receive two implants to support a 2- or 3-unit prosthetic bridge. The neck design determines the depth of implant placement:
Short group: coronal rough surface margin placed at bone crest (crestal placement)
Standard group: 1 mm subcrestal placement
Long group: 2 mm subcrestal placement
The trial adopts a parallel design, with a sample size of 30 patients (10 per group), allowing for adequate power while considering possible dropouts. Randomization will be performed electronically and concealed in opaque envelopes until surgery. Blinding is partially feasible, especially for radiographic and digital analysis where treatment allocation is masked.
Surgical procedures will be standardized using a fully digital workflow. Implants will be placed in healed sites without the need for bone grafting. Healing will be non-submerged using appropriate healing abutments. After three months, definitive zirconia bridges will be installed, and patients will be enrolled in a maintenance protocol.
In addition to comparing the impact of different neck designs and placement depths, the prosthetic crowns will be designed with two distinct emergence profiles: one simulating a natural root form extending apically, and the other adapted to the mucosal margin. This design will allow for the assessment of volumetric tissue adaptation based on prosthetic contour.
Primary outcomes will include longitudinal changes in marginal bone height evaluated through standardized periapical radiographs, CBCT, and digital scans. Secondary outcomes include:
Volumetric soft tissue changes assessed using superimposed 3D models derived from intraoral scans.
Comparison of tissue responses between the two crown designs (root-form vs. standard emergence).
Clinical parameters such as probing depth, plaque index, and bleeding on probing at designated follow-ups.
Radiographic and volumetric measurements will be performed by calibrated, blinded examiners. Imaging will be taken at baseline (prosthesis delivery), 6 months, and annually up to 3 years. Analytical methods include ANOVA or Kruskal-Wallis tests based on data distribution, with appropriate post-hoc comparisons and a significance level set at p \< 0.05.
This study is expected to contribute relevant clinical data to the ongoing discussion around subcrestal implant placement and the role of implant macro- and micro-geometry in maintaining peri-implant tissue health.
ARDEC Academy is the lead sponsor of 9 studies on the registry; none are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
-Known allergy or to implant materials used in the study-
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants in this arm receive one-piece dental implants with a short transmucosal neck (1.8 mm total height, hyperbolic convergent shape) placed at the level of the bone crest (crestal placement). The implant features a ZirTi surface and Ultrathin Threaded Microsurface across the entire neck.
Device: Short Neck Implant - Crestal Placement
Participants in this arm receive one-piece dental implants with a standard transmucosal neck (0.8 mm cylindrical plus 2.0 mm convergent portion) placed 1 mm below the bone crest. The implant surface includes micro-threads throughout the neck to promote tissue stability.
Device: Standard Neck Implant - 1 mm Subcrestal Placement
Participants in this arm receive one-piece dental implants with a long transmucosal neck (0.8 mm cylindrical plus 3.0 mm convergent portion) placed 2 mm below the bone crest. This arm tests the effect of deeper placement combined with extended neck geometry.
Device: Long Neck Implant - 2 mm Subcrestal Placement
A one-piece endosseous dental implant with a 1.8 mm short convergent neck, placed at the bone crest. Implant used: PRAMA implant (Sweden \& Martina, Italy) with UTM surface treatment.
A one-piece endosseous dental implant with a standard-length neck (2.8 mm total; 0.8 mm cylindrical + 2 mm convergent), placed 1 mm subcrestally. Implant used: PRAMA implant (Sweden \& Martina, Italy) with UTM surface.
A one-piece endosseous dental implant with a long transmucosal neck (3.8 mm total; 0.8 mm cylindrical + 3 mm convergent), placed 2 mm subcrestally. Implant used: PRAMA implant (Sweden \& Martina, Italy) with UTM surface.
Change in Peri-Implant Bone Height Over Time
Vertical changes in marginal bone level from the implant-abutment junction to the first bone-to-implant contact (BIC) at mesial and distal aspects, measured on standardized periapical radiographs, CBCT, and digital scans. Unit of Measure: Millimeters (mm)
Time frame: Baseline (prosthesis delivery), 6 months, and annually up to 3 years post-loading
Volumetric Change in Peri-Implant Tissues
Volumetric changes in peri-implant soft and hard tissues will be measured using 3D digital superimposition of intraoral scans. The analysis will compare changes over time in tissue volume surrounding each implant. Unit of Measure: Cubic millimeters (mm³)
Time frame: Baseline (prosthesis delivery), 6 months, and annually up to 3 years post-loading
Tissue Volume Difference by Crown Emergence Profile
Comparison of peri-implant tissue volume changes between crowns with root-shaped apical emergence profiles versus standard crown shapes. Unit of Measure: Cubic millimeters (mm³)
Time frame: 6 months and annually up to 3 years post-loading
Probing Pocket Depth at Implant Sites
Probing depth at six sites per implant to evaluate peri-implant health. Unit of Measure: Millimeters (mm)
Time frame: 6 months and annually up to 3 years post-loading
Plaque Index at Implant Sites (0-3 scale)
Plaque accumulation at implant sites assessed with a modified plaque index. Unit of Measure: Score on index scale (0-3)
Time frame: 6 months and annually up to 3 years
Bleeding on Probing at Implant Sites (percentage of sites)
Presence of bleeding upon probing at six sites per implant. Unit of Measure: Percentage (%)
Time frame: 6 months and annually up to 3 years
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: No — Individual participant data (IPD) will not be shared due to institutional policy and ethical considerations regarding patient confidentiality. Only aggregate-level results will be made publicly available through publications and study reports.
This study is active, not recruiting, as verified in Aug 2025. You cannot join it, but the record below documents what was studied.
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