One-Piece Implants in Narrow Ridges: Clinical Indications and Surgical Protocol

Narrow alveolar ridges represent one of the most frequent challenges in implant dentistry. Anatomical limitations in complex areas, like the anterior maxilla and mandibular premolar region, often restrict the use of standard-diameter implants without bone augmentation. In these situations, one-piece implants have emerged as minimally invasive alternatives that can simplify treatment, shorten healing time, and maintain ridge integrity. 

Unlike conventional two-piece systems, one-piece implants integrate the abutment and implant body into a single, cohesive structure, eliminating the microgap at the implant abutment interface but presenting other restorative challenges. While this configuration enhances mechanical strength and biological sealing, it also requires careful case selection and preparation to provide predictable results. 

Understanding One-Piece Implant Systems 

Design and Concept 

A one-piece implant is a monoblock device composed of an implant body and an integrated prosthetic abutment. This particular design eliminates the internal screw joint, typically of two-piece systems. As a result, it creates a continuous structure that minimizes micromotion, bacterial leakage, and potential screw-related complications and failures. 

On one hand, the absence of abutment connection simplifies the restorative workflow, allowing immediate provisionalization under the appropriate stability conditions. Most of these types of implants are made from grade 5 titanium, like the GDT OPI and ROT featuring surface treatments like roughening and blasting along the body to enhance osseointegration. They feature a polished neck for soft tissue integration, some models include a bendable neck for angulation flexibility, like the GDT OPIB and ROF.

Biomechanical Behavior 

Due to their cohesive behavior as one unit, occlusal forces are transferred directly through the implant without the potential micromovement that occurs at screw joints in two-piece systems. As a result, structural rigidity is increased and the risk of component fatigue or loosening is reduced.

On the downside, the monoblock structure limits prosthetic flexibility and restricts angulation correction and abutment customization compared to two-piece systems, which are considerably more flexible, adaptable, and versatile for multiple cases. Therefore, it’s essential to perform a precise implant positioning during surgery to maximize results.  

Clinical Indications for One-Piece Implants 

1. Narrow Alveolar Ridges

One-piece implant systems are particularly indicated for ridges measuring 4.0 mm or less in width, where a traditional implant would require bone grafting. Diameters between 2-9 mm and 3.5 mm allow insertion without ridge expansion or augmentation in most cases. 

Within the narrow alveolar ridges framework, they can be highly useful in:

• The anterior mandible, where bone is typically dense but under 4.0 mm.
• The anterior maxilla for single tooth replacement, in cases where occlusal loads are controlled.
• Healed extraction sites with limited buccolingual volume.  
  

2. Minimal Bone Grafting or Flapless Approaches 

One-piece systems are ideal for clinicians aiming to avoid large regenerative procedures when facing ridge limitations. Their slim design supports minimally invasive placement, reducing surgical trauma and healing time. When placed following a flapless approach, they can preserve periosteal blood supply and minimize crestal bone resorption. 

3. Immediate Loading

Due to their one-piece configuration and high initial stability, these implants are suitable for immediate provisionalization, particularly in the anterior mandible or when insertion torque exceeds 35 Ncm. Their integrated abutment removes additional microgaps during early healing, improving tissue response and blood supply. 

4. Avoiding Extensive Surgical Procedures 

Patients with medical or anatomical limitations, such as older adults, diabetics with controlled conditions, or patients unwilling to undergo grafting, can benefit greatly from one-piece implants, as they offer a simplified and predictable solution that reduces overall treatment time and morbidity. 

Advantages of One-Piece Implants 

• Reduced microgap: Their unified structure virtually eliminates the implant-abutment junction, reducing bacterial colonization and lowering the risk of peri-implant inflammation.
• Improved mechanical integrity: Without screwing, mechanical complications and fracture risks are practically eliminated as their continuous titanium body endures high fatigue resistance under cyclic load.
• Simplified Workflow: Placement and provisionalization can often occur in a single appointment, reducing treatment time and improving comfort for patients. Also, these implants eliminate abutment selection errors and simplify restorative steps.
• Cost-effectiveness: Fewer components and reduced chat time make them an economical alternative to more complex regenerative therapies or two-stage procedures.
• Preserved Crestal Bone: The absence of microgaps at the crestal level reduces bacterial-induced bone remodeling. Also, soft tissue integrates around the polished collar, keeping a stable mucosal seal. 

Limitations and Considerations 

Despite their multiple benefits, one-piece systems require careful case selection and preparation. Here are some crucial aspects to consider if you decide to use a one-piece system in your rehabilitation:

Limited Prosthetic Flexibility 

Their integrated abutment system makes the correction of angulation errors post-placement difficult, making 3D positioning during surgery an important step to achieve ideal results. 

Restricted Use in Posterior Regions 

Narrow-diameter one-piece systems are not designed to withstand the higher occlusal loads of molar zones, particularly in bruxers and patients with complex malocclusions.

Soft-Tissue Management 

While they can deliver excellent results with the correct planning, the abutment can protrude through the soft tissue from the moment of placement if the flap closure is not precise enough to ensure an esthetic emergence profile and avoid dehiscence.

Challenges in Immediate Loading 

Primary stability is primordial in these cases. Torque below 30 Ncm or placement in soft bone may contraindicate immediate function. 

Restorative Limitations 

Cement-retained restorations are the norm, as screw access is not possible. Thus, strict cement control is mandatory to avoid subgingival excess, irritation, and bacterial colonization. 

Using One-Piece Implants in Narrow Ridges 

Case Rationale 

In narrow ridges, ridge augmentation has traditionally been the standard approach. Yet, bone grafting increases treatment time, procedure cost, and morbidity. In contrast, one-piece implants provide a graftless solution by adapting implant geometry to the existing bone anatomy. 

Besides, modern narrow one-piece implants with surface-treated titanium, achieve comparable osseointegration to wider implants when adequate bone density is present. Their reduced diameter is clinically compared by improved surface area-to-volume ratio and enhanced thread design. 

Clinical Considerations 

• Bone type: Best results occur in dense cortical bone, preferably type I or II. In soft bone, the literature suggests under-preparation of the osteotomy to enhance stability.
• Implant length: Longer implants, above 12 mm, are preferred to distribute load over a larger area, improving primary stability.
• Occlusion: We must avoid heavy occlusal loading or cantilevers. Use mutually protected occlusion or light centric contacts.
• Soft tissue thickness: Ensure at least 2 mm of keratinized mucosa, particularly on buccal sites, to support a healthy peri-implant collar.
  

Surgical Protocol for One-Piece Implants 

1. Case Planning and Radiographic Assessment 

The use of digital workflow, preoperative CBCT, and surgical guides is essential to assess ridge width, bone height, and determine implant angulation. Ridge width should allow at least 0.5–1.0 mm of bone on both buccal and lingual aspects after implant insertion. 

2. Osteotomy Preparation 

In narrow ridges, a minimally invasive osteotomy is preferred: 

• Begin the procedure with a pilot drill, enlarging sequentially using narrow-diameter lance drills.
• Undersized the final osteotomy slightly, by 0.2–0.4 mm, to enhance primary stability.
• Maintain copious irrigation to avoid thermal necrosis.

Use specialized surgical kits, such as the GDT surgical kit for one-piece implants.

3. Implant Placement 

Insert the one-piece implant with controlled torque, ideally 35–45 Ncm. The abutment portion should emerge at the desired restorative angulation, and the platform should rest at or slightly below the crestal bone.

4. Soft Tissue Management 

Soft tissue must be gently adapted around the integrated abutment. In thin biotypes, use a small conservative flap or punch technique to contour soft tissues for esthetic emergence profiles. 

5. Immediate Vs. Delayed Loading 

Insertion torque is critical. If it’s ≥35 Ncm and patient occlusion is favorable, you can deliver a temporary restoration immediately. Otherwise, the implant should heal undisturbed for at least 8 weeks. 

6. Prosthetic Restoration 

With osseointegration confirmed clinically and radiographically:

• Take impressions using digital scanning techniques or open-tray if digital workflow options are not available.
• Use minimal cement volume during restoration to avoid excess.
• Verify occlusion rigorously to prevent lateral overload.
  
  

Postoperative Considerations 

• Control pathogenic factors with prescribed chlorhexidine rinses at 0.12% twice daily for 2 weeks.
• Avoid mechanical trauma or function on the implant during initial healing if not immediately loaded.
• Evaluate tissue response and stability at 1, 3, and 6 months.
• Once restored, schedule professional maintenance every 4-6 months with gentle mechanical cleaning and radiographic evaluation. 

Most cases depend on patient compliance to achieve long-term success. As a result, the patient's hygiene measures and the clinician's control of occlusal forces are essential. With the appropriate to achieve survival rates above 95%.

Advantages in the context of Narrow Ridge Management 

When used appropriately, one-piece implants allow clinicians to: 

• Avoid granting procedures in 60–80% of narrow ridge cases.
• Preserve native bone architecture and vascularity.
• Reduce chair time and patient morbidity.
• Achieve predictable esthetic outcomes in anterior sites. 
  
  

Scientific Evidence on One-Piece Implant Systems 

Comparative clinical trials have shown no significant difference in survival rates between narrow one-piece and standard two-piece implants over five years if insertion torque exceeds 30 Ncm and bone density is favorable. 

Risk Management  

While one-piece implants are biomechanically efficient, they are also technique-sensitive. Surgical inaccuracy cannot be corrected prosthetically, and cement control must be meticulous. Also, their use in high-load posterior areas should be restricted or reinforced by splinting multiple implants. 

As clinicians, we must always evaluate ridge anatomy, occlusion, and soft-tissue characteristics before choosing this approach. Fortunately, when case selection and execution are precise, complications are rare and bone stability is excellent. 

The Takeaway 

One-piece implants represent a reliable, minimally invasive alternative for rehabilitating narrow alveolar ridges without bone grafting. Their monoblock structure offers high mechanical stability, eliminates microgaps, and promotes favorable tissue response. 

However, their success depends on strict case selection, accurate surgical placement, and controlled loading, showing their best features in anterior or interforaminal regions where space is limited with sufficient bone density. Mastering one-piece implant protocols and sharpening the eye for the appropriate cases enables predictable and cost-effective implant therapy even in challenging anatomic conditions.

References

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2. Schiegnitz, E., & Al‐Nawas, B. (2018). Narrow‐diameter implants: A systematic review and meta‐analysis. Clinical Oral Implants Research, 29(S16), 21–40. https://doi.org/10.1111/clr.13272
3. Pieralli, S., Spies, B. C., Kohnen, L. V., Beuer, F., & Wesemann, C. (2020). Digitization of One-Piece Oral Implants: A Feasibility Study. Materials (Basel, Switzerland), 13(8), 1990. https://doi.org/10.3390/ma13081990
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