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Medicina Oral, Patología Oral y Cirugía Bucal (Ed. impresa)

versão impressa ISSN 1698-4447

Med. oral patol. oral cir. bucal (Ed.impr.) v.10 n.4 Valencia ago.-out. 2005

 

Clinical and radiographic behaviour of 290 dental implants with a surface treated with hydrofluoric acid and passivated with hydrofluoric and nitric acid: 
early loading results after 2 years
Comportamiento clínico y radiológico de 290 implantes con superficie tratada mediante un primer grabado 
de ácido fluorhídrico y un segundo de ácido fluorhídrico con ácido nítrico: valoración a los dos años de carga precoz

 

José María Martínez González (1), Cristina Barona Dorado (2), Jorge Cano Sánchez (3), María Flórez Rodríguez (3),
Miriam Cantero Álvarez (3)

(1) Profesor Titular de Cirugía. Facultad de Odontología. Universidad Complutense de Madrid
(2) Profesora Colaboradora. Facultad de Odontología. Universidad Complutense de Madrid
(3) Servicio de Implantología Bucofacial. Hospital de Madrid

Address:
E-mail: jmargo@ odon.ucm.es

Received: 28-05-2004 Accepted: 10-10-2004

Martínez-González JM, Barona-Dorado C, Cano-Sánchez J, Flórez-Rodríguez M, Cantero-Álvarez M. Clinical and radiographic behaviour of 290 dental implants with a surface treated with hydrofluoric acid and passivated with hydrofluoric and nitric acid: early loading results after 2 years. Med Oral Patol Oral Cir Bucal 2005;10:355-61.
© Medicina Oral S. L. C.I.F. B 96689336 - ISSN 1698-4447

RESUMEN

Objetivo: El presente trabajo ofrece los resultados sobre el comportamiento clínico y radiográfico, durante dos años, de 290 implantes tratados con un primer grabado de HF y un segundo de HF y HNO3 y que fueron sometidos a carga protética a las ocho semanas de su inserción.
Diseño del estudio: Se trata de un estudio observacional prospectivo sobre 290 implantes colocados en 56 pacientes con un rango de edad entre 28 y 81 años. La selección se hizo previo estudio radiológico de proyecciones panorámica y tomográfica para realizar posteriormente el tratamiento implantológico con carga protésica y control evolutivo clínico (15 días, 1, 3, 6, 12, 18 y 24 meses) y radiológico (12 y 24 meses).
Resultados: Durante el período de precarga hubo fracaso en 11 implantes, lo que representa un porcentaje de éxito del 96,21%. Tras la colocación de la prótesis, a los dos meses, hubo que proceder a la retirada de cuatro implantes por lo que se han mantenido con éxito, doscientos setenta y cinco implantes.
Conclusiones: El seguimiento y resultados favorables tras la carga protética de 279 implantes (98,56% de éxito), corroboran que la carga precoz puede y debe ser aplicada, tras una minuciosa planificación y selección de los casos.

Palabras clave: Implantes, grabado ácido, carga precoz.

ABSTRACT

Objective: This work presents the results of clinical and radiological behaviour, for 2 years, of 290 implants treated with a first etching with HF and a second etching with HF and HNO3 acids and that were loaded 8 weeks after insertion.
Experimental design: It is a prospective study on 290 implants placed in 56 patients with an age range from 28 to 81. The selection was previously made through radiological study with panoramic and tomographic radiographs, followed by the implantological treatment with prosthetic loading and clinical (15 days, 1, 3 , 6, 12, 18 and 24 months) and radiological control (12 and 24 months).
Results: During the healing period, 11 implants failed, resulting in a CSR of 96.21%. After prostheses placement at 2 months, 4 implants were retired, successfully remaining 275 implants.
Conclusions: The following and favourable results after the prosthetic loading of 179 implants (CSR of 98.56%), attest that early loading may and must be applied, after rigorous planning and case selection.

Key words: Implants, acid etching, early loading.

 

INTRODUCTION

Since 1969, when Brånemark (1) published its first results, dental implant treatments have been continuously modified. One of the modified parameters has been the pre-load intervals, so the healing time of 3 to 6 months, in order to achieve a correct osseointegration, has been greatly reduced.

Initial reports from Ledermann (2) about the possibility of immediate implant loading described the use of TPS implants in overdenture treatments, with survival rates of 91.2%.

Afterwards, authors as Babbusch (3) and Chiapasco (4) have corroborated these results with different dental implant surfaces, and have observed that many of the failures occurred between six and twelve months.

Another form of shortening the treatment is the so-called early loading, when the implants are loaded 6-8 weeks after insertion, with similar results to the standard protocol.

Lazzara et al (5) studied a total of 429 implants that were loaded 2 months after insertion, with a success rate, at 12 months, of 98.5%.

Martínez-González et al (6) reported, in their preliminary results of early loading treatments, a success rate of 95.7%.

These and other studies have created new perspectives in the planning and development of treatments with dental implants. It is obvious that most of this advance is due to a better understanding of the biological aspects of the bone-implant interface, but it is also due to the development of new implant surfaces.

While smooth titanium surfaces were the fundamental elements for the osseointegration, some protocols have been developed that replaces smooth implant surfaces with rough ones. From a biological and biomechanical perspective, the conditions of cell adhesion and bone deposition improve on a rough surface, with faster healing time and possibility of application in bone of worse quality (7).

Implant roughness can be produced with different treatments, and presently the most used methods are blasting, anodic oxidation, hydroxyapatite plasma-spray and chemical etching. The last one produce surface roughness through the action of chemicals like hydrochloric, sulphuric, hydrofluoric or nitric acids, like the SLA®, Osseotite® and Defcon® surfaces.

This paper provides the clinical and radiological results after 2-year follow-up of 290 dental implants with the surface treated with an acid etching with hydrofluoric acid followed by a passivation with hydrofluoric and nitric acid (Defcon TSA® implant).

MATERIALS AND METHODS

This study comprised total of 56 patients (36 female and 20 male) with a mean age of 56.33 years and a range between 28 and 81 years.

The patients were briefed and clinically explored before their inclusion in the study, excluding those cases with serious systemic problems or uncontrolled mouth diseases. The jaw relation and available space, specially for fixed restorations, were exhaustively reviewed. Pre-operative radiographic exploration included, in all cases, a panoramic radiography and Dentascan tomographic studies.

An incision was placed in mid-crestal position to elevate full-thickness flaps. The surgical ferulae was positioned and bone site was prepared following the drill sequence recommended by the implant manufacturer, starting with a surgical opening drill, followed by pilot, series 3 and/or series 4 drills with continuous cooling. The implants inserted (Defcon TSA® implant) have a surface treated with acid etching (hydrofluoric acid) followed by passivation (hydrofluoric and nitric acid)). After implant placement with submersed technique (2 stages), the flaps were sutured with a 00/000 suture silk.

All patients were informed about the possibility of postoperative symptoms and they were prescribed antibiotics (1 week), analgesics and anti-inflammatories (4 days).

Patients were indicated to avoid loading over the treated zone during healing time, except for those patients with complete prostheses who were permitted its use although it was modified to be tissue-supported.

The sutures were removed 10 days after surgery, and clinical controls every 15 days were established for seven weeks, with radiographical controls previous to initial loading.

Implant connection to the healing abutment was made in most cases with a circular incision, in order to preserve as much tissue as possible.

Once completed the planned prosthetic treatment, proper instruction for handling and care were given to the patients, applying clinical controls at 15 days, 1, 3, 6, 12, 18 and 24 months, evaluating the motility and condition of the peri-implant tissue. At 12 and 24 months radiological evaluations were made, consisting on panoramic and periapical radiographs.

RESULTS

1.- Anatomical distribution (Fig. 1):

The distribution, depending on the anatomical region, was of 58.96% (171 implants) for maxillae and 41.03% (119 implants) for the mandible.

Quadrant distribution was: 31.72% (first quadrant), 27.93% (second quadrant), 20.68% (third quadrant) and 19.65% (fourth quadrant).

2.- Bone quality and quantity :

Bone quality distribution was: class I bone (16.20%), class II bone (43.79%), class III bone (34.82%) and class IV bone (5.18%).

Panoramic radiography and tomographical studies determined that the patients had a bone height between 10 and 16 mm, with the following distribution for implant length: 10mm (23.44%), 11.5mm (11.37%), 13mm (59.31%) and 16mm (5.68%). (Fig.2)

Bone width allowed the use of series 3 dental implants (body diameter of 3.4mm and head diameter of 3.7mm) in a 65.86% of the cases, and series 4 dental implants (body diameter of 4.0mm and head diameter of 4.7mm) in a 34.13% of the cases.(Fig.3)

3.- Postoperative clinical controls

Patient evolution was nominal for this kind of surgical procedure. Signs of low-moderate inflammation (72%) and haematoma (28%) were detected. Inflammatory response were reported with a mean of 4 days, while haematomas were reported during 13 days.

In 22% of the cases a second-stage surgery was not necessary, as the cover screws appeared through the overlaying mucosa. In these cases, hygienic procedures were extreme, counselling the patient the application of chlorhexidine spray on the exposed regions.

4.- Pre-load radiological controls

Radiological controls (panoramic and periapical) were made 7 weeks after insertion, registering implant failure in 11 cases (3.79%), 8 of them in class IV bone.

5.- Prosthetic load

Load was applied to the restorations 8 weeks after insertion. In maxillae 71.66% of the restorations were fixed prostheses and 28.33% overdentures, while in mandible 65.47% were fixed prostheses and 34.25% overdentures.

Acrylic provisional prostheses were placed for 2-4 months before insertion of the final prostheses, except for the overdentures, that were definitive.

6.- Post-load clinical controls.

Post-load clinical controls were scheduled at 15 days, 1 month, 3, 6, 12, 18 and 24 months, evaluating movement and periimplant gingival state.

Only 4 implants in different patients were retired due to movement 1 month after insertion. The other 275 implants presented no signs of failure.

7.- Post-load radiographical controls

Panoramic and periapical projections were performed at 12 and 24 months. An accumulated bone loss of 0.2-1.2 mm was detected, without detection of periimplant radiolucency.

In a similar way of the pre-load controls, panoramic a periapical projections were made at 12 and 24 months, with absence of periapical radiolucency in all cases. The accumulated bone loss was of 0.2-1.2mm (Figs. 4, 5 and 6).

DISCUSSION

The existing surface treatments for dental implants favour a reduction of healing times for prosthetic loading of the implants. Some of the surface treatments produce a roughness through etching techniques with different acids that promotes an improved bone apposition.

Defcon® surface, produced with hydrofluoric and nitric acids, achieves a controlled roughness with a mean value of two micrometer. This technique removes particles and surface contamination of titanium surface. Acid etching nor modifies the material microstructure neither affects mechanical properties, while producing a homogeneous roughness.

The chemical etching is complemented with a chemical passivation of the titanium surface, improving corrosion resistance. The advantages of the immersion in a slightly oxidant acid solution are a reduction of an order of magnitude of electrochemical corrosion compared to untreated samples, as well as a 50% reduction of ion release.

The clinical application of this surface allows an early loading at 8 weeks of the implants with results comparable to that of the standard loading protocol. However, this values are not only due to the surface treatment. Besides, a correct planning is one of the basis for implant success.

Implant length and width suggest the kind of bone anchoring it will be achieved, with a worse prognosis/success rates for those cases with reduced length and diameter.

In this study, implant length reached values from 10 to 16 mm, and diameter values over 4 mm. Theses values are similar to those used in other studies, like Roynesdal (8), who studied early loading with ITI implants of similar lengths.

Bone quality is probably one of the most important factors for osseointegration. Poor bone quality, porous and with small retention is not uncommon in dental implantology, so new macrogeometric designs and surface treatment of the implants seek, mainly, to elicit a more favourable reaction of bone.

Bone quality class IV found in this study were low (5.18%), but 8 of the 11 failures suffered during pre-load stage were placed in this bone quality. In a study from Lazzara et al (5) it is remarkable that, for 429 implants studied, 30.7% were placed in soft bone. Even with this unfavourable condition, the authors reported success rates over 97%, although it was not stated if failures occurred in soft bone.

Another key factor to evaluate the prognosis of early loading is to evaluate the effect of early loading on the results. In this study, from 279 implants clinically and radiographically defined as osseointegrated only four were lost after one month of loading. This fact corroborates findings of other authors, confirming somehow that a correct bone-implant contact can be achieved 2 months after insertion with a suitable response to masticatory loads.

It is important to remark that only overdenture treatments received definitive restorations for. The correct adjustment of the bars to avoid micromovements of the implants and the fact that the loads are soft tissue borne favours a more suitable force distribution. On these same principles it is based the immediate load that advances even more the prosthetic loading (9).

In fixed prostheses, loading started with the placement of a provisional acrylic restoration, while other similar studies use definitive reconstructions. However, an influence in the results was not found. The premises in which this protocol are based are the application of a more progressive load and frequent examination of soft tissue behaviour and the patient response through his hygienic cares.

Post-load bone resorption values (0.2-1.2 mm) do not differ from the ones observed in standard protocols. This fact, as well as the lack of any implant loss after 2 years (279 implants / 98.56% success rate), corroborate that early loading can and must be applied, after a meticulous planning and case selection.

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