PATZi protocol in atrophic maxillary full-arch implant rehabilitations

Pretam Gharat explores the evolution of immediate full-arch implant rehabilitation and introduces the PATZi protocol, a systematic approach designed to improve planning, stability and predictability when treating patients with severely atrophic maxillae.

Professor Per-Ingvar Brånemark discovered osseointegration in 1952. He treated the first human patient with a full-arch fixed dental prosthesis supported by titanium fixtures in 1965. This breakthrough shifted modern implantology away from removable dentures toward fixed, bone-anchored full-mouth rehabilitation (Kim, 2014; Nevins and Janson, 2015; Kochar et al, 2022; Brånemark, 1961).

In the early 1990s, Prof Paulo Malo started exploring immediate load full-arch implant dentistry.

By 1998, he had perfected a protocol, which is now known as the all-on-four approach in full-arch implant rehabilitations.

The all-on-four method differs from classical Brånemark protocols by using fewer implants, tilting the posterior fixtures, avoiding bone grafts, and loading the prosthesis immediately.

What facilitated immediate function

• Shift to primary stability over time: clinicians observed that if an implant is anchored into the bone with high insertion torques (typically ≥ 35–45 Ncm), it eliminates microscopic movements. Primary mechanical stability effectively protects the biological process of osseointegration during the initial healing phase (Muthaiyan et al, 2025; Cheng et al, 2025)
• Macromedial and surface engineering: smooth, machined titanium surfaces (common in original Brånemark implants) evolved into rough, oxidised, or acid-etched surfaces (such as Nobel Biocare’s TiUnite texture). These micro-rough surfaces accelerated blood clot attachment and bone apposition. Tapered implant designs also increased bone compression upon insertion (Chiapasco et al, 1997; Brånemark et al, 1999; Glauser et al, 2001)
• The splinting effect: For full-arch cases, connecting multiple implants together immediately with a rigid temporary bridge acts like an internal orthopaedic cast. The individual forces are distributed across the entire arch, preventing any single implant from overloading or moving (Maló et al, 2003).

Legg et al (2023) demonstrated that IFAL (Immediate Full Arch Loading) significantly improves tooth related quality of life.

Introducing the PATZi protocol

A standard configuration all-on-four approach to restore full-arch maxillary fixed implant prostheses is not without its pitfalls. Intraoperative challenges such as bone quality and quantity, may sometimes not allow for execution of the original treatment plan. Extensive maxillary sinus pneumatisation directly limits the available vertical bone height in the posterior maxilla, forcing dental implants to be placed further forward (anteriorly), compromising the A-P spread. This anatomical constraint triggers a cascade of biomechanical challenges when planning full-arch or multi-unit implant restoration and leads to a shortened dental arch or excessive cantilever forces.

The PATZi protocol is a systematised algorithm for maxillary full-arch implant treatment planning that addresses such intraoperative surprises and achieves full arch length in the planned prosthesis. PATZi also assigns a numbering classification to each implant configuration, which leads to uniform communication and grading of surgical difficulty, as well as predictable planning for developing future salvage plans. By using the PATZi protocol as a guideline, the surgeon may improve composite torque value and anteroposterior (AP) spread, eliminate distal cantilever forces, and ultimately improve the predictability of the prosthetic treatment plan (Ponnusamy et al, 2023).

PATZi protocol workflow

• P – Pterygoid implants for dense posterior remote anchorage
• A – Anterior implants (axial, nasopalatine, or transnasal)
• T – Tilted or angled implants in the mid-maxillary region
• Z – Zygomatic implants utilised if P, A, and T sites prove insufficient
• I – Immediate loading of the prosthesis (if insertion torque and stability allow).

The concept

PATZi employs immediate loading and remote anchorage concepts developed over the past 35+ years to produce a near infinite combination of dental implant setups to accommodate nearly any situation that may present in atrophic maxillae. PATZi starts with attempted placement of pterygoid implants to employ their numerous benefits of cantilever elimination, additional support, maximising anterior-posterior spread and increasing composite torque value (Holtzclaw, 2018; Holtzclaw, 2020; Holtzclaw, 2023).

If pterygoid implants are successfully placed, the algorithm then proceeds anteriorly. Anterior prosthetic support may be attained with standard axial, nasopalatine, piriform rim, or transnasal fixtures (Maló et al, 2003; Urban et al, 2015; Lorean et al, 2014; Camargo et al, 2019).

If anterior support can be achieved, PATZi then proceeds to achieve mid-maxillary support via tilted implants which may be of either traditional or trans-sinus varieties (Ponnusamy et al, 2023; Jensen et al, 2012). If pterygoid or mid-maxillary tilted implants are not successful, PATZi calls for placement of a posteroinferior zygomatic implant. Alternatively, failure to achieve placement of an anterior implant necessitates placement of an anterosuperior zygomatic implant.

In the event that multiple zygomatic implants are required in a single malar process, the presence or absence of a pterygoid implant will influence the configuration of the zygomatic fixtures: parallel versus ‘A-frame’ (Holtzclaw, 2023).

If a pterygoid implant is present, the zygomatic implants can be placed in a parallel configuration. Parallel zygomatic implants will result in a smaller A-P spread, which is a disadvantage. However, they have the benefit of more superior malar real estate for the placement of a second zygomatic implant and eliminate the possibility for collision with the anterosuperior zygomatic fixture. The disadvantage of a posteriorly located posteroinferior zygomatic implant is offset by the pterygoid implant which maximises AP spread and eliminates the prosthetic cantilever. If a pterygoid implant is not successfully placed, zygomatic implants are placed in an A-frame setup with the posteroinferior fixture placed in a more posterior position. Placement in this manner distalises the prosthetic platform of the posteroinferior zygomatic implant, shortening the resultant cantilever of the restoration.

Alternatively, the A-frame setup brings the posteroinferior zygomatic implant apex closer to the orbit, thus reducing available real estate for the anterosuperior zygomatic fixture and increases the risk of implant collision.

The application of the PATZi protocol is done independently to the left and right sides of the maxilla. 

Conclusion

Successful full arch maxillary rehabilitation begins from preliminary planning of the case. Specifically, in atrophic maxillae, the PATZi protocol; combining Pterygoid, Anterior, Tilted, and Zygomatic Implants has emerged as a systematic approach to address these challenging cases.

Advantages of the PATZi protocol

• Avoids major grafting procedures
• Improves AP spread and prosthetic stability
• Reduces stress on anterior implants
• Assists with immediate full-arch loading – a very important outcome from an oral health quality of life perspective (Legg et al, 2023)
• Standardises communication and planning between surgical and prosthetic teams.

References

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21. https://www.implantdentistrytoronto.ca/blog/full-arch-implant-planning-the-patzi-protocol – Accessed on 23.08.2026 10:47GMT
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This article is sponsored by Dr Pretam Gharat.