Dental ImplantsNCT07073196
Single Implant Crowns Supported by Narrow or Standard Diameter Implants in Molar Sites
A study testing Dental implant treatment (narrow implants) and Dental implant treatment (standard implants) in people with Dental Implants, run by Mohammed Bin Rashid University of Medicine and Health Sciences at 1 site in United Arab Emirates.
Trial summary
Standard dental implants require sufficient bone and spacing, which may not be available in all patients. To address these limitations, narrow diameter implants (≤3.5 mm) have been introduced as a less invasive alternative, especially useful for medically compromised patients or those avoiding bone grafts. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Dental Implants
- What is being tested?
- Dental implant treatment (narrow implants) and Dental implant treatment (standard implants)
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 40 participants
- Where
- 1 siteUnited Arab Emirates
- Study dates
- 1 Oct 2025to 1 Dec 2029
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Aged ≥ 18 years.
- Require replacement of single missing molar tooth with dental implant in fully healed sites.
- Controlled oral hygiene (full-mouth plaque and bleeding scores ≤ 25% at baseline).
- Intact adjacent teeth and opposing dentition.
- Fully healed sites (≥ 6 months) with limited bone availability in the horizontal bucco-lingual dimension (residual bone width of ≤ 6 mm) and minimal height of 8 mm.
- Good compliance and commitment to attend follow-up review appointments.
- Willing to provide informed consent.
Who cannot join
- Localized/generalized periodontitis.
- Any medical condition that may contraindicate implant treatment (Bornstein et al., 2009).
- Bone metabolic disease and/or taking medications that affect bone metabolism.
- Long term use of non-steroidal anti-inflammatory medications.
- History of malignancy, radiotherapy or chemotherapy.
- Pregnant or lactating women.
Show all 9Show fewer
- Smokers.
- Severe bruxism or parafunctional habits.
- Large occlusal discrepancies.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United Arab Emirates1 site, 1 recruiting
- Recruiting
MBRU
Dubai
Momen A Atieh, BDS, MSc, DClinDent, PhD, FPFA, +9714 383 8905, momen.atieh@dubaihealth.ae
About this study
Official title: Single Implant Crowns Supported by Narrow or Standard Diameter Implants in Molar Sites: a Randomized Controlled Trial
Standard dental implants require sufficient bone and spacing, which may not be available in all patients. To address these limitations, narrow diameter implants (≤3.5 mm) have been introduced as a less invasive alternative, especially useful for medically compromised patients or those avoiding bone grafts. However, narrow implants made of pure titanium have shown long-term biological and technical concerns.
The introduction of titanium-zirconium (TiZr) alloy has improved mechanical strength, and several studies have demonstrated favorable outcomes with narrow TiZr implants. Yet, evidence remains limited regarding their exclusive use in high-load posterior (molar) regions. Prior studies report conflicting failure rates, potentially linked to prosthetic design and occlusal forces, but lack quantitative analysis of bite forces or prosthetic angles.
Emergence angle, prosthetic platform width, and implant-abutment connection may all influence implant stability and peri-implant tissue health. A newly introduced TorcFit™ connection may offer better stress distribution and torque resistance, but its clinical relevance-especially in narrow implants used for molars-remains untested.
Read the detailed description
Introduction (background and research question)
Standard diameter dental implants require sufficient bone volume and adequate interdental distance to prevent adverse bone level changes, or unfavorable long-term esthetic outcomes. To overcome site specific limitations, simplify treatment protocols, and expand clinical applications, short (< 10 mm) and narrow diameter (≤ 3.5 mm) implants were introduced. It has been suggested that narrow diameter dental implants would allow a less invasive surgical procedure by reducing the need for bone augmentation, a viable option for medically compromised patients and those averse to the use of bone grafting materials. However, the use of narrow diameter implants of commercially pure titanium (cpTi) has been associated with several biological and technical concerns when used over a long period of function.
The use of titanium and zirconium (TiZr) alloy improved the mechanical properties and several clinical studies showed that narrow diameter TiZr implants had high survival rates and comparable performance to standard diameter cpTi implants across various clinical indications. The clinical outcomes of narrow diameter TiZr were also comparable to standard diameter implants of the same TiZr material when replacing single missing teeth in the anterior or posterior regions of the maxilla or mandible. On the other hand, the use of narrow diameter TiZr implants to support single crown restorations exclusively in the posterior region remains limited. One randomized controlled trial has reported on the clinical outcomes of single narrow (3.3 mm) diameter TiZr implants in molar sites. These studies reported failure rates of 1% and 18% at one- and three-year follow-up, respectively. The failed narrow diameter implants were regular neck (RN) with prosthetic platform of 4.8 mm and were mostly lost because of implant fracture below the internal screw channel. Traumatic occlusal forces were thought to be the reason behind these failures. However, the occlusal wear or the bite forces on these narrow implant-supported crowns were not quantitatively assessed.
While it could be speculated that the wider prosthetic platform of 4.8 mm diameter might have caused unfavorable leverage on the narrow diameter implant body placed in sites of high occlusal load (i.e., single molar sites), wider prosthetic platform in molar sites may provide favorable prosthetic design and emergence profile that could be associated with greater stability of peri-implant hard and soft tissues. Different prosthetic-related factors, particularly the restorative angles and emergence profile, may have significant impact on marginal mucosal and bone levels and increase the risk of developing peri-implantitis. Narrow diameter implants might be associated with implant restorations with an emergence angle of > 30° in molar sites. The long-term outcomes of implant restorations with different emergence angles were recently evaluated in a systematic review. While significant differences were not observed in terms of periodontal and esthetic outcomes, the authors concluded that platform-matched implant restorations with an emergence angle of ≤ 30° might be associated with less changes in peri-implant marginal bone levels when compared to implant restorations with an emergence angle of > 30°. However, the evidence support was of low to moderate certainty and further studies are still required.
Another reason that has been implicated in the biological and technical complications of dental implants is the poor fit and instability of the implant-abutment connection. Narrow diameter Straumann tissue level dental implants have 15° internal cone with either four internal CrossFit® grooves or 8° morse taper synOcta® connection. These configurations allow flexible positioning of the prosthetic components but evidence on using narrow diameter implants with either CrossFit® or synOcta® connection in molar sites remains insufficient. Recently, a new implant-abutment connection has been introduced with the premise of ensuring transmission of high torques. The stability of the new TorcFit™️ implant-abutment connection was shown to be similar to that of the CrossFit® connection. However, the TorcFit™️ connection, with its 7° conical connection and six-sided star-shaped anti-rotational element, may allow transmission of higher torques, maintain a flexible alignment of the prosthetic components, and ensure uniform stress distribution. It is yet to seen to what extent this new implant-abutment connection influences the clinical performance of a narrow (3.3 mm) or standard (4.5 mm) diameter implant in the replacement of single missing molars.
Aim(s) of the study:
The objectives of this single-center three-year randomized controlled trial will be:
To evaluate the clinical, and radiographic outcomes of narrow and standard diameter TiZr implants used to support screw-retained monolithic zirconia crowns in molar sites.
To evaluate the long-term effects of the restorative emergence angle on the peri-implant mucosal level, marginal bone level, periodontal parameters and prevalence of biological complications.
- Conditions
- Dental Implants
- Being tested
- Dental implant treatment (narrow implants), Dental implant treatment (standard implants)
- Keywords
- Dental implants
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Dental implant treatment (narrow implants)Procedure or surgery
Replacement of a missing molar tooth with a narrow dental implant
Dental implant treatment (standard implants)Procedure or surgery
Replacement of a missing molar tooth with a standard dental implant
| Study group | Role | What they receive |
|---|---|---|
| Narrow implants | Experimental | Narrow implants diameter 3.3 mm to replace missing molar tooth Receives: Procedure: Dental implant treatment (narrow implants) |
| Standard implants | Active comparator | Standard implants diameter 4.5 mm to replace missing molar tooth Receives: Procedure: Dental implant treatment (standard implants) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Peri-implant mucosal recession rate
The peri-implant mucosal margin will be assessed by measuring the clinical crown height and recorded as yes/no
Measured: Peri-implant mucosal recession rate will be assessed at three and twelve months
Secondary outcomes (7)
Emergence angle of implant restorations
Emergence angle of implant restorations will be measured on radiographs by recording the angle between the implant long axis and a line tangent to implant restorations
Measured: Three months
Implant success/survival rate
Implant success/survival rate will be assessed clinically after one year of implant restoration and annually up to three years. A successful implant is the one that will meet the criteria proposed by the European Federation of Periodontology (Albrektsson and Isidor, 1994), while a survived implant is the one that will remain in function but without meeting the success criteria. An implant is considered failed when it will be removed.
Measured: After 12 months and annually for three years
Changes in peri-implant marginal bone level
Changes in peri-implant marginal bone level will be assessed standardized periapical radiographs.
Measured: Three and twelve months
Implant stability measurements
Implant stability measurements will be recorded using an electronic handheld device (Osstell Beacon, W\&H, Göteborg, Sweden). The device uses the resonance frequency analysis (RFA) to measure the implant stiffness in implant stability quotient (ISQ) units (Sennerby and Meredith, 1998, Sennerby and Meredith, 2008). The ISQ scale ranges from 0 to 100 with values higher than 65 ISQ indicating a satisfactory implant stability (Atieh et al., 2012, Atieh et al., 2014, Sennerby and Meredith, 2008).
Measured: Baseline, three and twelve months
Need for bone augmentation
Need for bone augmentation with autogenous bone chips, xenograft and resorbable collagen membrane, as described by Buser and co-workers (2009) recorded as yes/no.
Measured: Baseline
The width and height of keratinized tissue
The width and height of keratinized tissue (Lang and Berglundh, 2011) will recorded using a manual periodontal probe (UNC-15 periodontal probe, Hu-Friedy®, Chicago, USA) and endodontic file (ISO 15).
Measured: At three months of implant restoration and then annually up to three years.
Prosthetic outcome
Prosthetic outcome will be determined using a modified United States Public Health Service (USPHS) criteria (Bayne and Schmalz, 2005, Muhlemann et al., 2020). Each crown will be assessed on 12 parameters: patient satisfaction, ceramic fracture/chipping, abutment screw loosening, abutment screw fracture, debonding of titanium base abutment, fracture of titanium base abutment, loss of screw access restoration, marginal fit of abutment to implant, proximal contacts, occlusal contact, color match to neighboring teeth/restorations and opposing tooth/restoration fracture.
Measured: At 12 months and annually for three years.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Jul 2025
- Study start1 Oct 2025 (estimated)
- Primary completion1 Feb 2028 (estimated)
- Study completion1 Dec 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Dental ImplantsStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Prospective, in which participants will be recruited and then followed up throughout a specified period of time. Randomized, parallel designed, concurrent controlled trial with participants randomly allocated to either test or control groups.
- Masking
- None (open label)
- Enrolment
- 40 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Mohammed Bin Rashid University of Medicine and Health Sciences
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Momen Atieh, Mohammed Bin Rashid University of Medicine and Health Sciences
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07073196
- Sponsor's protocol ID
- MBRUMHS - June 2025
- Other IDs
- MBRU IRB-2025-110
- Status last verified
- Jul 2025
- First submitted
- 28 Jun 2025
- Last updated
- 18 Jul 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 18 Jul 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Single Implant Crowns Supported by Narrow or Standard Diameter Implants in Molar Sites: a Randomized Controlled Trial
- ClinicalTrials.gov ID
- NCT07073196
- Acronym / sponsor ID
- MBRUMHS - June 2025
- Conditions
- Dental Implants
- Keywords
- Dental implants
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 40 participants (estimated)
- Lead sponsor
- Mohammed Bin Rashid University of Medicine and Health SciencesUniversity, hospital or other
- Study start
- 1 Oct 2025 (estimated)
- Primary completion
- 1 Feb 2028 (estimated)
- Study completion
- 1 Dec 2029 (estimated)
- First posted
- 18 Jul 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Standard dental implants require sufficient bone and spacing, which may not be available in all patients. To address these limitations, narrow diameter implants (≤3.5 mm) have been introduced as a less invasive alternative, especially useful for medically compromised patients or those avoiding bone grafts. However, narrow implants made of pure titanium have shown long-term biological and technical concerns.
The introduction of titanium-zirconium (TiZr) alloy has improved mechanical strength, and several studies have demonstrated favorable outcomes with narrow TiZr implants. Yet, evidence remains limited regarding their exclusive use in high-load posterior (molar) regions. Prior studies report conflicting failure rates, potentially linked to prosthetic design and occlusal forces, but lack quantitative analysis of bite forces or prosthetic angles.
Emergence angle, prosthetic platform width, and implant-abutment connection may all influence implant stability and peri-implant tissue health. A newly introduced TorcFit™ connection may offer better stress distribution and torque resistance, but its clinical relevance-especially in narrow implants used for molars-remains untested.
Detailed description
Introduction (background and research question)
Standard diameter dental implants require sufficient bone volume and adequate interdental distance to prevent adverse bone level changes, or unfavorable long-term esthetic outcomes. To overcome site specific limitations, simplify treatment protocols, and expand clinical applications, short (< 10 mm) and narrow diameter (≤ 3.5 mm) implants were introduced. It has been suggested that narrow diameter dental implants would allow a less invasive surgical procedure by reducing the need for bone augmentation, a viable option for medically compromised patients and those averse to the use of bone grafting materials. However, the use of narrow diameter implants of commercially pure titanium (cpTi) has been associated with several biological and technical concerns when used over a long period of function.
The use of titanium and zirconium (TiZr) alloy improved the mechanical properties and several clinical studies showed that narrow diameter TiZr implants had high survival rates and comparable performance to standard diameter cpTi implants across various clinical indications. The clinical outcomes of narrow diameter TiZr were also comparable to standard diameter implants of the same TiZr material when replacing single missing teeth in the anterior or posterior regions of the maxilla or mandible. On the other hand, the use of narrow diameter TiZr implants to support single crown restorations exclusively in the posterior region remains limited. One randomized controlled trial has reported on the clinical outcomes of single narrow (3.3 mm) diameter TiZr implants in molar sites. These studies reported failure rates of 1% and 18% at one- and three-year follow-up, respectively. The failed narrow diameter implants were regular neck (RN) with prosthetic platform of 4.8 mm and were mostly lost because of implant fracture below the internal screw channel. Traumatic occlusal forces were thought to be the reason behind these failures. However, the occlusal wear or the bite forces on these narrow implant-supported crowns were not quantitatively assessed.
While it could be speculated that the wider prosthetic platform of 4.8 mm diameter might have caused unfavorable leverage on the narrow diameter implant body placed in sites of high occlusal load (i.e., single molar sites), wider prosthetic platform in molar sites may provide favorable prosthetic design and emergence profile that could be associated with greater stability of peri-implant hard and soft tissues. Different prosthetic-related factors, particularly the restorative angles and emergence profile, may have significant impact on marginal mucosal and bone levels and increase the risk of developing peri-implantitis. Narrow diameter implants might be associated with implant restorations with an emergence angle of > 30° in molar sites. The long-term outcomes of implant restorations with different emergence angles were recently evaluated in a systematic review. While significant differences were not observed in terms of periodontal and esthetic outcomes, the authors concluded that platform-matched implant restorations with an emergence angle of ≤ 30° might be associated with less changes in peri-implant marginal bone levels when compared to implant restorations with an emergence angle of > 30°. However, the evidence support was of low to moderate certainty and further studies are still required.
Another reason that has been implicated in the biological and technical complications of dental implants is the poor fit and instability of the implant-abutment connection. Narrow diameter Straumann tissue level dental implants have 15° internal cone with either four internal CrossFit® grooves or 8° morse taper synOcta® connection. These configurations allow flexible positioning of the prosthetic components but evidence on using narrow diameter implants with either CrossFit® or synOcta® connection in molar sites remains insufficient. Recently, a new implant-abutment connection has been introduced with the premise of ensuring transmission of high torques. The stability of the new TorcFit™️ implant-abutment connection was shown to be similar to that of the CrossFit® connection. However, the TorcFit™️ connection, with its 7° conical connection and six-sided star-shaped anti-rotational element, may allow transmission of higher torques, maintain a flexible alignment of the prosthetic components, and ensure uniform stress distribution. It is yet to seen to what extent this new implant-abutment connection influences the clinical performance of a narrow (3.3 mm) or standard (4.5 mm) diameter implant in the replacement of single missing molars.
Aim(s) of the study:
The objectives of this single-center three-year randomized controlled trial will be:
To evaluate the clinical, and radiographic outcomes of narrow and standard diameter TiZr implants used to support screw-retained monolithic zirconia crowns in molar sites.
To evaluate the long-term effects of the restorative emergence angle on the peri-implant mucosal level, marginal bone level, periodontal parameters and prevalence of biological complications.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- Prospective, in which participants will be recruited and then followed up throughout a specified period of time. Randomized, parallel designed, concurrent controlled trial with participants randomly allocated to either test or control groups.
| Arm | Type | Receives |
|---|---|---|
| Narrow implants | Experimental | Procedure: Dental implant treatment (narrow implants)Narrow implants diameter 3.3 mm to replace missing molar tooth |
| Standard implants | Active comparator | Procedure: Dental implant treatment (standard implants)Standard implants diameter 4.5 mm to replace missing molar tooth |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (7 listed)
- Aged ≥ 18 years.
- Require replacement of single missing molar tooth with dental implant in fully healed sites.
- Controlled oral hygiene (full-mouth plaque and bleeding scores ≤ 25% at baseline).
- Intact adjacent teeth and opposing dentition.
- Fully healed sites (≥ 6 months) with limited bone availability in the horizontal bucco-lingual dimension (residual bone width of ≤ 6 mm) and minimal height of 8 mm.
Key exclusion criteria (9 listed)
- Localized/generalized periodontitis.
- Any medical condition that may contraindicate implant treatment (Bornstein et al., 2009).
- Bone metabolic disease and/or taking medications that affect bone metabolism.
- Long term use of non-steroidal anti-inflammatory medications.
- History of malignancy, radiotherapy or chemotherapy.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Dental implant treatment (narrow implants)Replacement of a missing molar tooth with a narrow dental implant | Procedure or surgery | Narrow implants |
| Dental implant treatment (standard implants)Replacement of a missing molar tooth with a standard dental implant | Procedure or surgery | Standard implants |
Primary outcome
Peri-implant mucosal recession rate
Time frame: Peri-implant mucosal recession rate will be assessed at three and twelve months
The peri-implant mucosal margin will be assessed by measuring the clinical crown height and recorded as yes/no
7 secondary outcomes
Emergence angle of implant restorations
Time frame: Three months
Implant success/survival rate
Time frame: After 12 months and annually for three years
Changes in peri-implant marginal bone level
Time frame: Three and twelve months
Implant stability measurements
Time frame: Baseline, three and twelve months
Need for bone augmentation
Time frame: Baseline
The width and height of keratinized tissue
Time frame: At three months of implant restoration and then annually up to three years.
Prosthetic outcome
Time frame: At 12 months and annually for three years.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 18 Jul 2025.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Dental implant treatment (narrow implants) and Dental implant treatment (standard implants) in people with Dental Implants, run by Mohammed Bin Rashid University of Medicine and Health Sciences at 1 site in United Arab Emirates.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 9 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 18 Jul 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United Arab Emirates. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Momen A Atieh, BDS, MSc, DClinDent, PhD, FPFA (+9714 383 8905, momen.atieh@dubaihealth.ae), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Peri-implant mucosal recession rate (time frame: Peri-implant mucosal recession rate will be assessed at three and twelve months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 18 Jul 2025.