Context and challenges of implant rehabilitation

The rehabilitation of edentulism is currently based on two paradigms: conventional (crestal) implantology and basal implantology. While conventional implants, anchored in the alveolar bone, benefit from extensive clinical hindsight, their success is strictly dependent on sufficient bone volume, often requiring grafting procedures or sinus lifts. Conversely, basal implants exploit dense cortical bone, offering a graft-free alternative with immediate loading, a crucial option for patients presenting with severe bone resorption or requirements for rapid treatment.

Objectives and scope of the analysis

The authors of this review compare the biological principles, design characteristics, and surgical protocols of these two systems. The objective is to provide an evidence-based assessment of the clinical indications, advantages, and limitations of each approach. The analysis evaluates whether the bicortical anchorage of basal systems can offer predictability comparable to classic alveolar osseointegration, while simplifying the management of complex maxillary atrophies. This work aims to guide the practitioner in selecting the most suitable system based on the patient's anatomy and loading requirements.

Methodology of the literature review

The authors conducted an exhaustive literature search to compare conventional and basal implant systems. This synthesis is based on data extracted from five major electronic databases: PubMed/MEDLINE, Scopus, Google Scholar, Web of Science, and the Cochrane Library.

The selection protocol was based on the following parameters:

• Study period: Publications published between 2000 and 2025.
• MeSH keywords and terms: Use of combinations including "dental implants", "conventional implants", "basal implants", "osseointegration", "immediate loading" and "atrophic jaw rehabilitation".
• Inclusion criteria: Systematic reviews, meta-analyses, randomized controlled trials (RCTs), prospective and retrospective clinical studies, as well as narrative reviews published in English.
• Exclusion criteria: Studies without sufficient clinical data, case reports with limited sample sizes, conference abstracts, and unpublished manuscripts.

The analysis process was conducted sequentially by the authors, including an initial evaluation of titles and abstracts, followed by a detailed review of the full texts. This methodology aimed to compare the biological principles, design characteristics, surgical protocols, and clinical outcomes of the two implant approaches.

Comparative synthesis results

Compiled data confirms that conventional (crestal) implantology achieves survival rates exceeding 95% over a decade. This performance is correlated with stabilized osseointegration over a healing period of three to six months. Conversely, basal systems exploit cortical bone density to allow immediate loading, eliminating the systematic need for grafts or sinus lifts.

L'évolution technologique a conduit à l'abandon des implants de type lame ou disque au profit des designs vissés, offrant une stabilité primaire supérieure. Les auteurs de cette revue précisent que les modifications de surface, qu'elles soient additives (hydroxyapatite, plasma spray) ou soustractives (sablage, mordançage acide), sont essentielles pour favoriser l'adhésion cellulaire et la migration ostéogénique.

• Stability: Conventional screw-retained implants offer high predictability in healthy alveolar bone thanks to the combination of macro and micro-threads.
• Complexity: Basal implants are indicated for severe resorptions and medically compromised patients seeking a rapid solution.
• Components: The conventional system uses a modular structure (cover screw, healing abutment, final abutment) to optimize soft tissue sealing.

Analysis of Crestal vs Basal Duality

This review highlights a major turning point: the transition from shape-based implantology (blades, disks) to biological and mechanical stability implantology. For the practitioner, the data confirms that the crestal system remains the reference for its long-term predictability, with survival rates exceeding 95% over ten years, provided that the alveolar bone volume is sufficient. Conversely, the basal approach emerges as a pragmatic alternative for severe atrophy, allowing to bypass bone grafts or sinus lifts through direct cortical anchorage.

The limitations of this synthesis lie in the increasing complexity of categorizing dental implant surfaces. Although micro-roughness is identified as a major lever for osseointegration, the multiplication of manufacturing techniques makes universal standardization difficult. Furthermore, the history recalled by the authors — notably the failure of disk or pin implants — warns against designs generating excessive bone trauma or fibrous interposition, unlike current screw-type implants which promote optimal bone-to-implant contact.

In practice, the choice should no longer oppose the two systems but integrate them according to the clinical situation. The conventional protocol allows flexibility between immediate loading or a two-stage submerged approach, which is essential in cases of limited primary stability. The basal design, often monobloc, meets the requirements for speed and reduced morbidity for patients with high immediate aesthetic or functional demands. In the dental practice, selection will therefore depend on the available bone density: alveolar bone for crestal and cortical bone for basal.

Summary of results

This review highlights that conventional implants display a survival rate exceeding 95% over ten years, although they often require sufficient bone volume or grafting procedures. Conversely, basal systems exploit cortical bone to allow immediate loading, offering an effective alternative for severely atrophied jaws.

In concrete terms, for the practitioner:

• Opt for the conventional system for standard cases to benefit from long-term documented predictability.
• Consider the basal approach as a graft-free solution for patients presenting significant bone resorption or contraindications to reconstructive surgeries.
• Adapt the protocol (one or two stages) according to the primary stability achieved: the submerged approach protects osseointegration in cases of compromised bone quality.

Technical lexicon: Understanding the fundamentals of conventional and basal implantology

Osseointegration: A fundamental concept established by Branemark in the 1950s. It refers to the direct structural and functional connection between living bone and the surface of a synthetic implant, ensuring the long-term stability of the restoration under functional load.

Basal implants: Implant systems, often monobloc, designed to anchor in highly mineralized cortical bone. Their design allows for the rehabilitation of severely atrophied jaws without resorting to bone grafts, while allowing immediate loading.

Bone-to-implant contact (BIC): Key histomorphometric indicator measuring the percentage of the implant surface in direct contact with the bone. In this review, BIC is closely linked to the macro-design (micro and macro-threading) which optimizes the distribution of mechanical stresses.

Two-stage approach: Prudent surgical strategy where the implant is submerged under the mucosa during the initial healing phase. This approach is preferred in cases of limited primary stability or concomitant bone augmentation procedures.

Primary stability: Initial mechanical anchorage obtained during implant insertion. It is the critical decision factor for choosing between immediate, early, or delayed loading, and depends on the quality of the recipient bone and the design of the threads.

Healing abutment: Transmucosal component connected to the implant after surgical exposure (or during one-stage placement). Its role is to guide gingival healing and sculpt the emergence profile for the future prosthesis.

Cortical bone: Dense peripheral bone layer with low vascularization. Unlike the alveolar bone used in conventional implantology, cortical bone serves as a primary support base for basal implants due to its high mechanical resistance.

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