Immediate implant placement and immediate restorations have been demonstrated to be predictable treatment methods. For the patient, an immediate approach means less treatment time and fewer surgical interventions.

“An immediate approach means less treatment time and fewer surgical interventions”

But to what extent should an immediate approach be the preferred option? Can indications and contra-indications for these procedures be clearly defined? Will there be a biological price to pay in the long-term for going faster?

The morphological changes which take place in the alveolus following tooth extraction have been extensively studied, and this knowledge should be applied to clinical cases. The tissue outcomes in thin versus thick phenotypes should be considered. We need to know if it is possible to predict how much buccal bone is going to be lost and whether a late or immediate approach can really make a difference regarding these changes.

According to a recent meta-analysis of immediate implant placement and immediate loading in the aesthetic area (Del Fabbro et al. 2015), implants placed in a healed ridge had higher implant survival rates (99.4%) than implants placed immediately after extraction (95.6%). This result was also confirmed by another comparative metanalysis last year with similar figures (Mello et al. 2017). Although the late approach is still considered the ‘gold standard’, survival rates of immediate approaches are high enough to be considered a viable option in the aesthetic area, thereby minimising treatment duration and improving patient satisfaction.

But implant survival isn’t the only important factor. A meta-analysis of soft and hard tissue changes following implant placement found no significant differences between conventional (late) and immediate protocols (Yan et al. 2016).

“Implant survival isn’t the only important factor”

Another meta-analysis found lower levels of mid-facial recession when an immediate approach with immediate provisionalisation was used in cases involving thick biotypes than when a delayed restoration protocol was used or when the cases involved thin biotypes (Kinaia et al. 2017).

Long-term clinical data reported retrospectively by the author and co-workers (Testori et al. 2017) found that immediate loading does not negatively influence the prognosis of immediate post-extraction implants.

“Immediate loading does not negatively influence the prognosis of immediate post-extraction implants”

One of the problems with immediate implant placement is that the sockets could potentially be infected. In this regard, weighted evidence suggests that implants can predictably be placed in sites with periapical and periodontal infections, provided that the socket is thoroughly debrided and decontaminated (Waasdorp et al. 2010; Chrcanovic et al. 2015). Last year, comparative results were published after a follow-up of four and a half years yielding results no different for post-extraction implants in infected sites than in non-infected sites (Zuffetti et al. 2017). A meta-analysis published this year came to the same conclusion concerning the aesthetic area, with no significant differences in survival rate and hard and soft tissue changes found between infected versus non-infected sockets (Chen et al. 2018).

Conclusions

• immediate implant placement has become a routine treatment protocol
• it is a technique-sensitive procedure and a learning curve should be taken in account
• in the aesthetic area, an immediate approach should be performed cautiously and always with the biological limitations in mind

The bone in contact with the root surface (called bundle bone) contains the collagen bundles from the periodontal ligament. The speaker said we can think of the bundle bone as a mineralised extension of the periodontal ligament. In the same way that the dental cementum is the mineralised ‘end’ of the periodontal ligament and connects the tooth to the periodontal ligament, the bundle bone is another mineralised end of the periodontal ligament which connects the ligament to the skeleton.

“We can think of the bundle bone as a mineralised extension of the periodontal ligament”

The speaker then posed the question: how much of the buccal bone wall is bundle bone? In 2011, the thickness of the buccal bone wall in the aesthetic zone was measured in 250 individuals. It was found that the average buccal bone wall was 0.6mm. The buccal wall was greater than 1mm in only around 15% of individuals included (Januário et al. 2011).

Significant anatomical differences can be found in the dimensions of the alveolar process and in the angulations of the roots relative to bone inclination.

The alveolar socket can be thought of as an ideal four-wall ‘bone defect’ which has very good blood clot stability, blood supply and cell source. The speaker described the histological healing process of the socket, which had been illustrated in a previous publication (Araújo & Lindhe. 2005). In this publication, the dimensional changes which the alveolar process and buccal crest underwent were highlighted.

“The alveolar socket can be thought of as an ideal four-wall ‘bone defect’”

This marked reduction of alveolar dimension has been clinically measured in CBCT studies comparing the alveolar process surrounding teeth with edentulous alveolar ridges in the anterior maxilla (Misawa et al. 2016; Chappuis et al. 2013). Thin-wall phenotypes were found to suffer a mean bone loss of 7.5mm while thick-wall types decreased by only 1.1mm.

The speaker concluded his presentation by saying that clinicians should acknowledge the importance of buccal bone wall thickness. They should recognise that tooth extraction will be followed by ridge reduction, and further clinical steps should be considered to compensate for this loss.

“Clinicians should acknowledge the importance of buccal bone wall thickness”

Testori

In the aesthetic area, there are a number of factors which have to be under control before surgical treatment can commence. Some cases would become nightmares if treatment were performed without the required biological knowledge.

The speaker presented a case involving a vertical fracture in the root and a fistula in an upper central incisor. The other incisor had deep root resorption which was preventing any potential conservative treatment of the tooth. The anatomy was maintained and the buccal bone wall was still suitably thick. The speaker outlined the diagnostic parameters which should be evaluated (Kan et al. 2018):

• gingival level (in relation to adjacent teeth)
• osseous and gingival tissue interface at facial aspect
• bone sounding of adjacent teeth (using a peri-apical radiograph)
• gingival biotype (which can be determined by probing – Colorvue Biotype Probe System® (Hu-Friedy) developed by Giulio Rasperini & Tiziano Testori)
• sagittal root position (by CBCT if required)
• labio-palatal width
• inter-radicular mesiodistal width
• tooth shape (diagnostic wax-up)

Before placing the implant, the fistulous tract should be removed to prevent contamination from the biofilm which used to be inside the fistula. The steps which should be observed during the surgical procedure are (Kan et al. 2018):

• minimally traumatic extraction (cutting the root into pieces with a piezoelectric saw)
• evaluation of the labial bony plate with a periodontal probe
• correct 3D implant position (85% of patients present a class I sagittal relationship (Kan et al. 2011), which is safest for immediate implant placement). Guided implant placement is highly recommended
• primary implant stability (no less than 45Ncm)
• evaluation of the gap (between implant and vestibular bone plate)

Positioning the longitudinal implant axis along the future incisal edge is a new concept recommended for use with a shoulderless abutment. The final profile will then be provided by the restoration (Scutellà et al. 2015).

Araújo

When faced with a tooth that needs to be extracted, we should ask ourselves if there is enough volume in the alveolar envelope to support the planned restoration. If the answer is yes, then ridge preservation will be enough. If not, then an approach involving ridge augmentation beyond the existing skeletal envelope will be required when extracting the tooth.

Animal histologic studies have shown that grafting with anorganic bovine bone (ABB) can minimise the loss of buccal bone in the socket (Araújo M et al. 2008; Araújo M et al. 2009; Araújo M et al. 2011). These results have also been clinically confirmed (Araújo et al. 2015).

In cases involving buccal bone dehiscence, we can still use a flapless approach by inserting a barrier membrane between the periosteum and the buccal bone wall. The barrier is then folded, covering the socket, and placed under the palatal soft tissue margin.

The speaker went on to say that these two techniques could actually be combined. Grafting the gap between the implant and the buccal wall can help preserve the volume and compensate for reduction in the bone wall (Araújo et al. 2010).

An immediate protocol would not be ideal when there is inadequate bone volume or acute infection at the extraction site, or when the predictability of the aesthetic result is low. An example of this would be in cases involving a thin biotype and a buccal wall < 1mm thick.

How fast can we go?

As fast and predictably as possible. However, proper anatomy and skill is absolutely necessary.

What is the role of late implant placement in implant dentistry?

When immediate placement is not possible, late implant placement is used to compensate for the lack of adequate conditions which meant that an immediate approach was not suitable.

An immediate protocol cannot be performed without a careful evaluation of the patient. Testori emphasised that favourable cases should have:

• good anatomy: at least 4mm of palatal bone is required to stabilise the implant
• good implant positioning: with 2–3mm gap left to fill with graft materials, and non-vestibular positioning
• good abutment shape: the thinner the abutment, the thicker the soft tissue around the implant neck will be

According to Araújo, narrow-diameter implants are mostly recommended in the anterior region; ridge preservation may be indicated in the molar region when the alveolar process is in close contact with the sinus floor.

“Narrow-diameter implants are mostly recommended in the anterior region”

The socket shield technique may be a good option when the root is oriented towards the buccal aspect and the bony wall is very thin. But the procedure is labour-intensive and complex, and should be limited to cases when it is clinically indicated.