Scientifica implantology

Numeri Uno 2014; 01: 20-21

BONE AND GINGIVA REGENERATION WITH IMMEDIATE POST-EXTRACTION IMPLANTS

The perception of success in implantology does not necessarily coincide with the technical concepts involved, but sometimes this must be combined with the expectations and desires of patient.
The case presented here is of a patient seeking implant rehabilitation of her lower frontal sector, although her greatest anxiety was to avoid repeating the experience of a number of implants she had been fitted with many years before, and which, although still satisfactorily functional, had become aesthetically unsightly due to the exposure of metal at the gingival margins.
Given that case presented significant recession at the level of the canines, the professional challenge – apart from the obvious need for functionality – centred on successfully achieving a uniform emergence profile in the forthcoming restoration supported by implants.
The teeth were extracted and the extraction sites and bone defects caused by the infective pathology were meticulously curetted.
Three Sweden & Martina Outlink2 implants with external connections were fitted, with lengths 13 mm and diameter 4.10 mm.
The discrepancies between the implants and sockets and the concomitant bone defects were filled with an insert of a particulate alloplastic material, and the area was covered with resorbable collagen membranes. Similarly, the area of gingival recession was compensated for with a dermal matrix that was sutured together with the membrane and the coronally repositioned flap.
After waiting 3 months to achieve an acceptable maturation of the tissues, a screw-retained ceramic prosthesis was fitted, with gingival emergence profiles that – fortunately – the patient approved.

Journal of Oral Implantology 2014;40:313-319

Implant peri-apical lesion (IPL) is a periapical lesion, usually asymptomatic, in which the coronal portion of the implant achieves a normal bone to implant interface. A case of IPL following immediate implant placement and treated with guided bone regeneration (GBR) principles is described. Five-year clinical and radiographic follow-up with cone-beam assessment showed complete healing of the bone. GBR principles applied to IPL could completely solve the lesion.

Numeri Uno, 19: 12-14, 2014

IMPLANT TREATMENT FOR THIN CRESTS: SPLIT-CREST OR GBR?

Introduction: Surgical treatment on thin alveolar crests for implants has always been a difficult task, even for the most experienced implantologists. The many surgical techniques suggested in literature may confuse clinicians to a certain degree in the choice of the correct surgical technique to be used.
The main surgical techniques found in literature can essentially be divided into two basic groups:

• Split-crest techniques, which aim to divide the thin crest present into two parts to be opened out, thus creating an intraosseous bone defect delimited by the two split cortices.
• Regenerative techniques, which leave the residual thin crest intact and increase the thickness of the crest with the application of a block or particulate graft, protected by a membrane or a titanium mesh.

Numeri Uno, 16: 6-9, 2013

SYSTEMATIC REGENERATIVE APPROACH TO MORPHOLOGICAL AND FUNCTIONAL INTEGRATION IN IMPLANT SUPPORTED PROSTHESES

The treatment of sectors of great aesthetic importance with implant prostheses is particularly critical even when post-extraction apicocoronal and buccolingual bone dimensions are substantially conserved. However, the “mere” loss of the root eminence and the papillae is sufficient to produce anatomical deficits that if not adequately compensated for can compromise the results of prosthetic rehabilitation. Over the last two decades numerous surgical regeneration techniques have been developed to allow anatomy to be corrected so that implants that are adequate in dimension, location and inclination can be inserted. Some of these techniques are complex and involve the use of membranes together with biomaterials, as well as multiple surgical phases to be able to correct alterations of the mucogingival tissues induced by the bone regeneration procedures. Furthermore, to treat a single case it is often necessary to put together different techniques devised to resolve single parts of the problem, such as bone deficit, malformations of the mucogingival tissues, the positioning of the implants or the pontics, etc. The systematic ESE approach addressed by this case report promotes the morphological restoration of the osseo-mucogingival peri-implant matrix (osseous and mucogingival tissues) in a single surgical phase. It uses implants, posts and the overlying prosthetic devices as essential features for peri-implant tissue morphogenesis.

Gaceta Dental, 2014, 260(7): 174-186

PERI-IMPLANT BONE REGENERATION WITH BIPHASIC TRICALCIUM PHOSPHATE AND POLYLACTIC ACID

A clinical trial was carried out on 27 patients. When their implants were inserted, a bone filler material was used, composed of hydroxyapatite (HA), beta tricalcium phosphate, (TCP) and polylactic acid (PLA) combined in the same product. TCP is an osteoinductive material that is completely and physiologically resorbed. The HA acts as an indispensible support for the facilitation of bone regeneration. PLA has a double function, on the one hand the stabilization of the TCP and HA, and on the other as an occlusive barrier in bone regeneration procedures.
This has been used as a graft in cases of preservation of the crest, dehiscences and in association with the insertion of immediate implants. The radiological results (density similar to bone), clinical results (functional implant) and results for soft tissues (keratinized gingiva without inflammation) were highlighted in all cases, and the most frequent complication was the exposure of the graft material, which occurred as a consequence of secondary epithelialization granulation tissue.
Simplicity of management, the easy treatment of complications and the effectiveness demonstrated during the study make it possible to use the combination of TCP, HA and PLA in bone regeneration procedures in the field of implantology.

The International Journal of Oral & Maxillofacial Implants, 2014;29:699-704

This study involved 23 patients who all needed two teeth extracted. In each patient, one site was left to heal without using biomaterials. The other site was treated with the insertion of porcine bone. After 3 months, Outlink2 implants were inserted, and 3 months later the width of the buccal ridge was measured. The sites treated with porcine bone maintained significantly greater bone volume at molar positions, but there were no statistically significant differences at other positions (incisors, canines, premolars).

Clinical Oral Implant Research, 2012; 23 Suppl 6: 136-146

In the authors’ opinion, the studies included in the review are not sufficient to uphold the necessity for the presence of keratinised mucosa around implants. However, the most frequent clinical indication is to adopt surgical techniques able to maintain not only the bone complex but also the mucosa, so as to preserve tissue stability over time and a good aesthetic result.

Journal of Oral Implantology, Early View, First published online in 2012, November

In 85 patients, 131 implants were inserted with partial thickness flap preparation. The surgical technique is able to preserve keratinized tissue and, at the 4-year follow-up, an excellent stability of the soft tissues was noted, correctly recreated with an increased thickness while the reconstructions had a pleasing aesthetic appearance.

Clinical Oral Implants Research, 2013; 24: 77-86

The osteointegration of implants positioned in sites previously regenerated with native bone and with deproteinized bovine bone mineral particulate was tested in vivo. Three months after the operation, all the implants were well integrated, in the sites where there had been serious original defects some residual particles of deproteinized bovine bone mineral could still be found.

Implant-supported prosthetic rehabilitation in edentulous mandibles is nowadays the therapy of choice. However, dentists often have to deal with atrophic crests with reduced volumes in the bucco-lingual-palatal sense. This makes it diffi cult to obtain a correct rehabilitation that can satisfy the principles of anatomy, periodontal physiology, and above all chewing biomechanics. We now know that in order to have good and long-lasting osseointegration, it is necessary to have at least 2 mm of healthy bone around the implant. Furthermore, a prosthetically guided emergence profi le is an important factor for a correct placement of the prosthesis and excellent intermaxillary relationship. Sometimes in the past, in the presence of signifi cant atrophies, the emergence profi le was incorrect - either too palatal or too vestibular – and in the fi nal prosthetic phase dentists were forced to fi nd a compromise between functionality and aesthetics. This led to the birth of guided bone regeneration (GBR) techniques that partially fi xed these problems, overturning the concept of “inserting the implant where there is bone” to “regenerating the bone where an implant has to be inserted” for a correct implant-prosthetic rehabilitation according to the occlusal module. In the last 30 years, many surgical techniques have been developed aimed at increasing the atrophic crest. Many authors have proposed autologous onlay grafts on the cortices with intra-oral samples (jaw, chin, trigone, etc.), other authors on extra-oral sites, such as the iliac crest or the calvaria.
These methods, although they sometimes provide good results, are certainly very aggressive and come with a very high rate of post-operative morbidity and complications.
They also present some inevitable disadvantages:
− two operations are required for taking samples from the donating zone
− invasive for the patient
− longer healing times
− often result in signifi cant bone reabsorption in the long term.
Many studies are reported in literature that show reabsorption of 30-50% at fi ve years with samples taken from the iliac crest1.
To overcome these negative aspects connected to the bone grafts, many doctors have developed numerous techniques aimed at increasing the thickness of the crest by separating the two bone cortices (vestibular and palatal/lingual) in order to induce a spontaneous formation of newly formed bone inside these two cortices.
In 1985, Osborn2 was the fi rst to implement the crest splitting of the maxillary, with greenstick fracture, by implementing the distraction of the cortices with wedge osteotomy of increasing sizes. As seen, this technique was recovered, modifi ed and divulged by Bruschi and Scipioni in the 1990s, with the partial thickness fl ap surgical technique. In 1990, Buser D et al3-4 published a study on the increase of crest by means of GBR with e-PTFE and collagen membrane. Despite the fact that some of the results were good, with a bone increase from 1.5 to 5.00 mm, 5 patients out of 12 had problems of infections and dehiscence due to the use of the
membrane. In 1994, Bruschi and Scipioni supplied the results of fi ve years of studies conducted on 179 patients and 323 implants with the introduction of the “bone fl ap” i.e. a bone fl ap inside the partial thickness mucosal fl ap. This technique called Edentulous Ridge Expansion (ERE) allows creating an intra-bone space that, thanks to the maintenance of the periosteum, does not use membrane. The authors reported a success rate of 98.5%. Even more interesting was the fact that there was hardly any long term reabsorption. This was probably due to the maintenance of the periosteum, which ensures that the reparatory capabilities of the organism are not damaged. In 1998, these authors expanded on this concept and described a maxillary sinus lift associated to the ERE. This technique, called Localisation Management of Sinus Floor, associated the possibility of lifting the sinus fl oor to ERE, exploiting the medial wall of the palatal arch. Once again, excellent regenerative
and sinus lift results were obtained. In 2004, the ERE technique was performed on 40 patients at the Magna Graecia University of Catanzaro (Cristofaro), with the variant of inserting a hydroxyapatite biomaterial under the periosteum, and the results were comparable in terms of bone increase and stability over time.
Many other studies (Vercellotti, Ferrigno, Sheti, Malchiodi, Suh) obviously confi rmed, with some slight variations, the extreme reliability of this technique.
Obviously, not only does the surgical technique play an important role in this situation, but also the type of biomaterial and type of implant used.
There are dozens and dozens of biomaterials on the market, but we now know that it is fundamental that they are porous and crystalline, which can give a specific osteoinductive power to the biomaterial in question. Finally, the geometry of the surface of the biomaterial used is also critical for obtaining good bone regeneration, and the shape, morphology and surface of the implant used are discriminating factors for obtaining a good result.