Atrophic maxilla rehabilitation: the challenge of graftless techniques

The management of complete edentulism or posterior edentulous spaces in the maxilla frequently encounters severe bone atrophy and sinus pneumatization. While conventional protocols rely on guided bone regeneration or sinus lifts, these interventions increase morbidity, costs, and treatment times. Faced with these limitations, so-called "graftless" implant techniques — All-on-4®, All-on-6, and zygomatic implants — are emerging as less invasive alternatives for functional and immediate prosthetic rehabilitation.

This retrospective study, conducted across four private clinics in Poland between 2015 and 2020, aims to compare the clinical efficacy and complication incidence of these three specific approaches. The objective is to evaluate osseointegration rates and implant longevity over a 1 to 5-year follow-up, while identifying the risks inherent to each protocol. The authors test the hypothesis of clinical equivalence between these methods for the treatment of maxillae presenting moderate to severe alveolar resorption, in order to provide concrete benchmarks for selecting the optimal technique in daily practice.

Study methodology

This retrospective comparative study focuses on the rehabilitation of the edentulous maxilla or those presenting with severe atrophy. Data were collected between 2015 and 2020 across four private dental clinics in Poland. To ensure the validity of the comparison and limit operative bias, all procedures were performed by the same surgical team.

The clinical sample consists of 153 patients, men and women of all ages, in whom a total of 667 dental implants were placed. The authors analyzed the efficacy of three distinct implant techniques avoiding the use of bone grafts:

• The All-on-4® method;
• The All-on-6 method;
• Les zygomatic implants.

Inclusion criteria targeted patients with alveolar ridge atrophy and maxillary sinus pneumatization, allowing for rehabilitation without guided bone regeneration procedures or sinus lifts. The study aimed to identify the most frequently used technique, the one with the best clinical efficacy, as well as the complication rates associated with each approach.

Postoperative follow-up spanned a period of 1 to 5 years. Statistical analysis, intended to compare osseointegration rates and failures between the three groups, was performed using the χ² test and Fisher's exact test.

Analysis of clinical efficacy and complications

The analysis of the 667 dental implants placed reveals that the All-on-6 technique was the maxillary rehabilitation method most frequently chosen by the surgical team. In terms of safety, this approach shows the lowest complication rate in the study, at 3.70%. Conversely, the All-on-4® method was the least used and presents the highest failure rate, reaching 7.05%.

Statistical significance and osseointegration

Despite the numerical discrepancies observed between the groups, statistical analysis using χ² tests and Fisher's exact test revealed no statistically significant difference in osseointegration rates among the three evaluated methods. For zygomatic implants specifically, a lack of osseointegration was reported in 4.81% of cases, a figure that remains comparable to the other graftless techniques studied.

Clinical observations and follow-up

Clinical follow-up, spanning from 1 to 5 years, allows for several qualitative observations on the performance of these protocols:

• Effectiveness of graftless techniques: The three approaches (All-on-4®, All-on-6, and zygomatic) have proven to be viable alternatives to conventional methods, systematically avoiding the need for sinus lifts or guided bone regeneration (GBR).
• Prosthetic stability: The All-on-6 appears to offer increased predictability, likely related to the distribution of forces over a greater number of abutments, resulting in the lowest complication rate in the cohort.
• Immediate rehabilitation: The study confirms that these protocols significantly reduce overall treatment time and surgical trauma by minimizing the number of interventions required for patients presenting with moderate to severe maxillary atrophy.

Clinical relevance analysis

These data confirm that graftless techniques constitute viable and predictable alternatives to complex bone regeneration procedures. For the practitioner, the interest is twofold: a drastic reduction in surgical trauma and a significant shortening of treatment times. The choice between All-on-4, All-on-6, or zygomatic seems more related to the residual anatomy and the sought-after primary stability than to a statistical superiority of one system over another.

The absence of a significant difference between conventional and zygomatic implants is a key finding of this study. It suggests that, despite their technical complexity, zygomatic implants offer equivalent osseointegration safety in cases of severe atrophy. These results corroborate current literature trends advocating for simplified protocols to improve the acceptance of treatment plans.

However, this retrospective study has limitations. A follow-up limited to 5 years does not allow for a definitive conclusion on very long-term prosthetic durability. Furthermore, although the cohort is substantial, prospective studies on larger samples would remain useful to identify more subtle risk factors related to minor complications.

Summary of results

The analysis demonstrates a statistical equivalence in implant success among the three studied methods. All-on-6 presents the most favorable safety profile with only 3.70% of complications, while All-on-4® and zygomatic implants show 7.05% and 4.81% failure rates respectively over a 5-year follow-up.

In concrete terms, for the practitioner:

• Simplify your treatment plans: Switching to 'graftless' protocols eliminates the systematic use of sinus lifts or GBR, drastically reducing surgical morbidity and rehabilitation times.
• Prioritize All-on-6 if bone allows: This technique offers better clinical reliability (complication rate of 3.70%) compared to All-on-4®, suggesting superior mechanical stability.
• Validate the zygomatic option: In cases of extreme maxillary atrophy, this approach stands out as a predictable and reliable alternative to massive bone grafts, with a failure rate of less than 5%.

Technical lexicon of the study

All-on-4®: Implant-supported rehabilitation concept allowing for complete and immediate prosthetic restoration of the arch on only four implants, generally including two tilted posterior implants to avoid sensitive anatomical structures.

All-on-6: Extension of the All-on-4 approach using six implants to increase the stability and predictability of the prosthetic restoration in patients with sufficient posterior bone volume.

Zygomatic implants: Long implants (35 to 52.5 mm) anchored directly into the zygomatic bone (malar bone), used for the rehabilitation of severe maxillary atrophies to avoid massive bone grafts.

Maxillary sinus pneumatization: Physiological process of expansion of the sinus cavity within the alveolar process following tooth loss, reducing the bone height available for conventional implantation.

Osseointegration: Formation of a direct structural and functional connection between living bone and the implant surface. Its absence constitutes the main failure criterion evaluated in this comparative study.

Graftless technique: Surgical strategy aimed at rehabilitating atrophied jaws by bypassing guided bone regeneration (GBR) or sinus lift procedures through the use of tilted implants or extra-maxillary anchorages.

Information intended for healthcare professionals. This content may contain errors or truncated summaries. We recommend always verifying with the original source article. Delynov disclaims all responsibility for the use of this information. This document is not intended for patients or the general public.