5   Guidelines for Selecting the Appropriate Loading Protocol

G.O. Gallucci

5.1 Implant Loading Protocols in Edentulous Patients

While healing periods of 3 to 6 months have traditionally been considered critical for a predictable osseointegration of dental implants, modified surgical and loading protocols have also shown predictable outcomes. This chapter will discuss the relevant clinical guidelines for selecting the appropriate loading protocol for edentulous patients with implant/prosthetic rehabilitations.

Protocols for the treatment of edentulous maxilla and mandible with removable or fixed prostheses present a variety of options regarding the numbers of implants, their strategic distribution, the transitional prosthesis, and the definitive prosthetic design. These clinical considerations are generally assigned the highest level of importance and, ideally, should not be adapted to facilitate a specific loading protocol. Loading protocols only represent just another step of the treatment sequence, and their implementation should not alter the desired final implant/prosthetic design.

Multiple parameters have been identified as influential in achieving successful osseointegration with modified loading protocols in the completely edentulous arch. These factors include: patient health, oral conditions, occlusion and function/parafunction, characteristics of the proposed implant sites, implant size and shape, implant material and surface properties, implant distribution in the arch, as well as timing and methodology of implant placement including primary implant stability, loading procedures, and long-term maintenance.

As presented in Chapter 2, the following terms were adopted by the 4th ITI Consensus Conference for loading protocols in edentulous patients:

• Conventional loading. Dental implants not connected to prostheses are allowed a healing period of more than 2 months after implant placement.

• Early loading. Dental implants are connected to the prostheses between 1 week and 2 months subsequent to implant placement.

• Immediate loading. Dental implants are connected to the prostheses within 1 week subsequent to implant placement.

A separate definition for delayed loading is no longer needed, since it will be included under the definition of conventional loading.

In order to accurately present the guidelines for selecting the appropriate loading protocol, considerations for the edentulous maxilla and mandible with removable or fixed prosthetic designs will be analyzed separately.

Recommendations for loading protocols in edentulous patients discussed in this chapter are based on the validation process presented in Chapter 2.

5.2 The Edentulous Maxilla

In the case of maxillary rehabilitations, the implant/prosthetic design should ideally result from a careful patient selection and diagnostic planning. This allows for the selection of appropriate artificial teeth and emergence profiles, as well as occlusion, phonetics, lip and facial support, and esthetic parameters, all of which will determine treatment feasibility and the patient’s approval of the proposed treatment plan.

Parameters for loading protocols are of particular importance regarding the maxillary bone volume and density, the relationships of the maxillary sinuses with the alveolar process, and the resorption pattern after tooth extraction. The achievement of primary stability may be influenced by the placement of shorter or smaller-diameter implants to accommodate a reduced bone volume, or standard-size implants placed in bone of low density. In this context, the selection of a specific loading protocol is often based on the primary stability achieved after implant placement.

5.2.1 Conventional Loading for Maxillary Overdentures

This loading protocol describes the use of four to six implants placed in the edentulous maxilla and restored with an overdenture after a healing period of 2 months. The implant/prosthetic design includes four to six implants connected by a bar device or four to six free-standing implants (Table 1).

Some authors reported that optimal survival rates of maxillary overdentures can be enhanced with well-planned treatment protocols, including conventional loading and splinted implants. Maxillary overdentures with conventional loading have been clinically well documented with four to six splinted implants.

Recently, a minimum of four free-standing implants with locator abutments has been proposed to support palate-free maxillary overdentures. After a conventional healing time, prostheses were attached to the implants, resulting in a 100% survival rate at the 12-to 48-month follow-up. However, more extensive clinical trials would be needed to demonstrate the long-term outcomes of this simplified approach.

In general, a good level of evidence for maxillary overdenture is available, although still less than for mandibular overdentures, since only prospective and retrospective studies are available for analysis. Mean implant survival rates of 94.8% to 97.7% during a mean follow-up period of 5 years (range: 1 -10 years) have been reported in the literature, with a prosthetic survival rate of 91.4%.

5.2.2 Early Loading for Maxillary Overdentures

This approach describes overdentures on maxillary implants that were functionally loaded no earlier than 1 week after implant placement and no later than 2 months afterwards. Implant/prosthetic designs included four to six implants connected by a bar construction or four to six free-standing implants with locator attachments (Table 1).

An early-loading protocol with maxillary overdentures supported by splinted implants should ideally be reserved for cases where bone volume and bone density allow for excellent primary stability. In cases where implants have been placed in the extraction socket, in augmented bone, or in combination with a bone-augmentation procedure, an early-loading protocol would not be recommended.

The implant survival rate for early-loaded free-standing implants with maxillary overdentures has been reported to be 87.2% at the 2-year follow-up, so this implant/prosthetic design is not suitable for early loading with maxillary overdentures.

5.2.3 Immediate Loading for Maxillary Overdentures

Immediate loading with maxillary implant overdentures is a protocol in which a removable prosthesis is attached to the implants and placed in occlusal contact within 1 week after implant placement. Scientific evidence for this loading protocol and prosthetic design is scarce, so this protocol is not recommended (Table 1).

5.2.4 Conventional Loading for Maxillary Fixed Rehabilitations

This loading protocol describes the use of dental implants in an edentulous maxilla to support fixed prostheses after a healing period of 2 months. Prosthetic designs for maxillary fixed rehabilitations include: (1) a fixed splinted rehabilitation supported by four to six anterior implants (placed between the maxillary sinuses) and bilateral distal cantilevers; (3) a fixed splinted rehabilitation supported by six to eight anterior-posterior implants without bilateral cantilevers; and (3) a complete fixed segmented rehabilitation supported by eight anterior-posterior implants (Table 2).

Scientific evidence on fixed-implant rehabilitations in the edentulous maxilla reports implant survival rates ranging from 95.5% to 97.9%. A conventional loading approach is scientifically and clinically validated according to the validation methodology proposed at the 4th ITI Consensus Conference.

Conventional-loading protocols for maxillary fixed implant rehabilitations are indicated in cases with poor primary stability, in implants placed in association with bone augmentation, in short implants, or in implant/ prosthetic protocols with a minimal number of implants. Here, the number of implants and their distribution in the arch would affect the long-term implant survival rate. This is not the case for reduced healing periods, where this particular parameter plays an important role in early failures. Current scientific evidence for fixed implant rehabilitation in the edentulous maxilla indicates that a minimum of six implants with an anterior-posterior distribution presents a more favorable survival rate at 10 years than prosthetic designs with four or five implants with the anterior distribution only.

Since a conventional-loading protocol allows for at least a 2-month healing phase, one particular concern during this period is the provisional prosthesis. Options include relining the existing denture or the fabrication of a new complete removable prosthesis. It is critical at this stage to avoid direct contact between the denture base and the freshly placed implants. To reduce the load transferred from the prosthesis to these implants, it is advisable to use a soft relining material.

Table 1 Indications for loading protocols with maxillary overdentures.

Implant/prosthetic design
Conventional loading	CWD	CWD	CD	CD
Early loading	CD	CD	CID	CID
Immediate loading	CID	CID	CID	CID
Retention	Bar design (with or without cantilevers) over four splinted implants	Bar design over six splinted implants	Four free-standing implants with Locator or telescopic crown attachments	Six free-standing implants with Locator or telescopic crown attachments
Prosthesis	Palate-free overdenture	Palateless overdenture	Palateless overdenture	Palateless overdenture
Interarch relation	Adequate interarch space	Adequate interarch space	Reduced interarch space	Reduced interarch space

CWD: clinically well documented – light green

CD: clinically documented – yellow

CID: clinically insufficiently documented – red

M1: first molar, PM2: second premolar, PM1: first premolar, C: canine, LI: lateral incisor

→: Optional bar segment as a distal extension

Table 2 Indications for loading protocols with maxillary fixed rehabilitations.

Implant/prosthetic design
Conventional loading	CD	SCV	SCV	SCV
Early loading	CID	CD	CD	CD
Immediate loading	CID	CWD	CWD	CWD
Implant number and distribution	Four anterior	Six anterior	Six anterior-posterior	Eight anterior-posterior
Prosthesis	Full-arch with distal cantilevers	Full-arch with distal cantilevers	Full-arch	Segmented in four three-unit FPDs*
Clinics	Increased interarch space, adequate bone volume in the anterior maxilla	Increased interarch space, adequate bone volume in the anterior maxilla	Increased interarch space, adequate bone volume in the anterior/posterior maxilla	Increased interarch space, adequate bone volume in the anterior/posterior maxilla

SCV: scientifically and clinically validated – dark green

CWD: clinically well documented – light green

CD: clinically documented – yellow

CID: clinically insufficiently documented – red

M1: first molar, PM2: second premolar, PM1: first premolar, C: canine, CI: central incisor, LI: lateral incisor

*The segmentatio/>

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