Revisiting implant controversies
The US perspective
The definitions of loading protocols have not been modified since 2007 (Esposito et al., 2007):
- conventional loading: two months or more from implant placement
- early loading: between one week and two months
- immediate loading: within one week of implant placement
Immediate loading protocol is predictable
At the 6th International Team for Implantology (ITI) consensus conference in 2018, the protocol for immediate placement plus immediate restoration/loading was found to be clinically well documented with a mean survival rate of 98%. No significant differences were found in outcomes for full-arch fixed protheses supported by less than five implants compared to five or more implants, nor for when implants were angulated or axially positioned (Morton et al., 2018).
The load does not affect osseointegration unless the implant moves
At the time of placement, implant stability depends only on the friction between the surface and the bone. This primary stability is gradually lost over time due to osteoclastic activity, while a secondary stability increases as new bone forms (fig 1).
It is well known that implant stability is a pre-requisite for osseointegration. Load would be harmful if it caused mobility, as this would disrupt the bone-implant interface. Load does not affect the process of completing secondary stability, provided that proper primary stability is achieved at the time of placement and occlusal forces are under control (fig 2).
A clinically proven protocol
According to the speaker’s own protocol published in 2001 (Ganeles et al., 2001), successful treatment needs a number of diverse factors to be taken into account:
- adequate number and distribution of implants
- adequate quantity and quality of bone
- a rigid provisional restoration
- control of occlusal forces
- patient cooperation
- whole team integration (surgeon, laboratory, restorative) to have the treatment done in a short space of time
This protocol is more predictable in the mandible; with some small modifications it is also suitable in the maxilla. Revisiting the protocol now, the speaker said that some more factors should be considered.
What has changed today, in 2019, with respect to what was described in 2001?
A new classification for assessing both the timing of implant placement and loading combinations has been proposed, to optimise treatment selection (Morton et al., 2018). Hard and soft tissue deficiencies must both be considered because different types of bone resorption demand different types of solutions. There are also various classifications for evaluating the difficulty of implant placement, the type of prothesis needed and assessing whether immediate loading is suitable (Jensen et al., 2014) (fig 3).
An overnight provisional
In immediate loading approaches, the speaker proposed the immediate placement of a functional provisional (overnight provisional) made directly in the office. This would let the patient go home with teeth while their long-term provisional is fabricated in the laboratory.
The speaker described the procedure as follows: the previous diagnostic wax-up is duplicated to make two thermoplastic shells with a vacuum machine. Thus, the ideal position of the restoration is captured and any potential need to increase or reduce hard/soft tissues can be pre-planned. After implant placement in the planned positions, an impression and an occlusal record are taken with one of the two vacuum splints. The other splint is used to make the overnight provisional. This is made by filling the splint with self-curing resin once it is located exactly with a provisional abutment on the most stable implant. Meanwhile, the long-term provisional is manufactured in the laboratory.
Guide for the occlusal design of complete restorations with immediate loading
This guide is based on periodontal prostheses and was pioneered by Morton Amsterdam in the fifties. Its purpose is to minimise lateral movements, to protect periodontally compromised teeth.
Nowadays, digital tools are used to register occlusal schemes. Occlusal parameters can be integrated into digital workflows to have surgery pre-planned and the provisional pre-fabricated before surgery. So, it is no longer necessary to make the overnight provisional chairside (fig 4–5).
Immediate loading is not appropriate for inexperienced clinicians
Immediate loading has documented benefits, but it is a complex surgical and prosthodontic procedure. It is associated with higher risks of complications or failures than other loading options. Therefore, the speaker stated that it should only be performed by clinicians with the prerequisite clinical skill and experience. Immediate contour management and grafting may optimise aesthetic outcomes when significant augmentation or site development is not needed.