PGO Scientific journal

Techniques such as guided bone regeneration using bone fillers and membranes have been proposed to limit post-extraction bone resorption. The socket-shield technique was introduced in 2010; it was described by Hürzeler and is based on maintaining a vestibular root fragment as a means of preserving the bone cortex. The present work describes a clinical case of a coronary fracture in an upper central incisor; the vestibular portion of the root was preserved to maintain the vestibular cortical architecture and at the same time an immediately loaded implant was placed. After a 3-month follow-up, preservation of the peri-implant hard and soft tissues was evident. No alterations in osseointegration were observed and peri-implant marginal bone loss was almost nil.

It is concluded that the socket-shield technique appears to clinically preserve the mucosal architecture and bone tissue without causing peri-implant pathology.

Key words: alveolar process, partial extraction, immediate implant, socket shield.

Various biomaterials and methods have been proposed to preserve the alveolar ridge after tooth extraction, especially the labial table, which often resorbs and collapses easily. These procedures include immediate implant placement after tooth extraction, ¹ use of bone fillings in the alveolus and barrier membranes. ²

The submersion (immersion) technique is described as a technique that keeps part of the tooth root in the socket in order to preserve as much tissue as possible, as well as to avoid resorption of the bony ridge, the height of the interdental papilla and the width of the alveolar ridge.³ In order to keep the tooth root fragment within the alveolus, a root section has to be performed from mesial to distal and the palatal root fragment will be removed to allow the insertion of a dental implant at the same stage. Hürzeler et al. demonstrated that intentional preservation of the vestibular portion of the root can help to ensure physiological preservation of the bone structures if the implant is placed in the alveolus leaving 1mm of the natural root fragment.⁴

The present report describes a clinical case with a diagnosis of coronary fracture at the level of an upper central incisor which was partially extracted leaving the vestibular root fragment as a “shield” to preserve the cortical architecture and allow for immediate placement of a dental implant.⁵

Clinical case

A 54-year-old female patient attended for consultation due to a fracture of a tooth in the upper anterior sector. In the anamnesis, the patient reported that she was a non-smoker and had no systemic history. She is allergic to penicillins.

In the intraoral clinical examination, a fracture of the upper right central incisor was observed with the presence of gingival growth at the level of the root fragment, which was evident when smiling. The radiographic examination showed the absence of the clinical crown with no pathology in the periradicular area. Due to the aesthetic demands of the case, partial extraction of the fractured tooth using the socket-shield technique and immediate placement of a dental implant were planned. The patient was notified of the treatment options and after signing the informed consent the following treatment plan was carried out:

• PHASE 1: Education about biofilm as well as motivation in brushing technique.
• PHASE 2: Partial extraction of the upper central incisor, placement of a post-extraction dental implant and immediate loading of a provisional.
• PHASE 3: Fabrication of a customised abutment and subsequent placement of metal-ceramic crowns on the implant and the other three upper incisors.

Surgical procedure

The area to be treated was infiltrated with local anaesthesia (lidocaine 2% with epinephrine 1:80000). An intrasulcular incision was made at the palatal level of the upper central incisor, followed by reduction of the coronary portion of the root. M-D odontosection of the root fragment and atraumatic exodontia of the palatal portion was performed, taking care not to luxate the vestibular fragment. The remaining vestibular segment was reduced using a surgical drill, leaving a thin layer of the root while keeping the vestibular bone cortex intact. The drilling protocol was then performed for the placement of a dental implant, an internal connection IRES with a length of 3.7mm x 12mm in the socket, leaving 1mm of space between the vestibular surface of the implant and the root fragment, thus achieving primary stability of the implant with a torque of 45N (fig. 7).

The implant is inserted by filling the gap with OsteoBiol Gen-Os bone graft, a mixture of collagenised cortical-cancellous heterologous bone, a natural replica of autologous bone that conserves the same structure (matrix and porous form), the entire material is covered with an Evolution X-thin membrane (100% pericardium) (fig. 10). A provisional was placed on a titanium abutment and 4 zeros silk suture (fig. 12).

After the surgical phase, a soft diet was recommended. In addition, anti-inflammatory drugs (Diclofenac 50 mg every 8 hours for five days) and antibiotic therapy (Azithromycin 500 mg tablets every 24 hours for three days) were prescribed. This regimen was chosen due to the high concentration of the drug in the alveolar bone tissues and the fact that the patient is allergic to penicillin.¹¹

Clinical monitoring

After 10 days the soft tissue healing was adequate, there were no complications and the stitches were removed. After 2 months of healing, the implant is correctly integrated and ready for its definitive rehabilitation. In addition, the thickness of the vestibular cortex was preserved at 1mm.

The socket-shield technique described by Hürzeler has been gaining visibility as a valid method, in addition to immediate implant placement, for the preservation of the alveolar ridge. Atrophy of the alveolar ridge after tooth extraction has, above all, a negative impact on implant insertion and the subsequent prosthetic restoration, as well as compromising the aesthetic result.^6,7

In the present study, correct implant osseointegration, maintenance of the alveolar ridge and gingival contour were observed.^8,9 The results are consistent with the various studies performed on immediate implant placement using the socket-shield technique. With the root submersion technique (RST), retention of the periodontal ligament through the root fragment could eliminate bone resorption.¹²

In addition, proper stabilisation of the clot between the implant and the shield facilitates long-term bone neoformation.^13–15

Some studies have evaluated the safety of leaving root debris submerged in the alveolar bone and have concluded that these can be maintained as long as they do not become infected or mobilised, as they could act as foreign bodies and be a nidus of infection, however, if well selected and managed they are an element that preserves bone tissue and soft tissue dimensions. Filippi et al. mentioned that decoronation of ankylosed teeth is a simple and safe surgical technique to preserve alveolar bone prior to dental implant placement. Salama et al. ^15–17 also noted that SRT not only eliminates the risk of caries and periodontitis but that root retention allows maximum preservation of the surrounding alveolar bone and soft tissue.¹⁸

Retention of the buccal root shield during implant placement does not appear to interfere with osseointegration; moreover, it may be beneficial in preserving vestibular bone cortex.¹⁹

The socket shield technique with immediate implant placement prevents collapse of the vestibular wall.²⁰ Thus, this technique represents an alternative approach to conventional regeneration techniques. Its features include offering less invasiveness at the time of surgery and providing aesthetic results with effective preservation of tissue contours. Some authors even mention that the root fragment cement can be integrated with the dental implant.²¹

Immediate implant placement with the socket-shield technique achieves satisfactory results in terms of gingival contour and maintenance of the vestibular bone wall. Immediate implant placement with the socket-shield technique achieves stability and osseointegration without an observable inflammatory response.

The socket-shield technique requires less operative time for predictable aesthetic results and is more economical for the patient, as it avoids the use of biomaterials. However, it requires some operator expertise and cases must be carefully selected.

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