25 April 2021

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ORTHODONTIC MINI-IMPLANTS, GROWING PATIENTS AND BONE PRESERVATION IN AGENESYS: CASE REPORT

Authors: Elena Bazzini, Silvia Bagatta, Stefano Cattaneo, Giovanna Garattini

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The aim of this article is to estabilish that bicortically placed miniscrews can preserve bone density and morphology of the alveolar process, in a growing patient with agenesis of a lateral incisor.

According to international literature, we used a new method for temporary fixed replacement of missing teeth that allows the correct development of the alveolar process.

Material and Methods

A 16-year-old patient with agenesis of maxillary left lateral incisor (2.2), suffering from complete left unilateral cleft lip and palate (UCLP; the surgical protocol for the cleft closure included the gengivo-alveolo plasty), received a mini-implant that supported a temporary prosthetic tooth, after orthodontic treatment to open the agenesis space.

A Cone beam computed tomography (CBTC) was taken immediately before insertion of the mini- implant.

The miniscrew was placed in the site of agenesis, parallel to the occlusal plane, with a palatal to vestibular direction, under local anesthesia, mepivacaine 2% with vasoconstrictor (adrenalin).

A stainless steel sectional wire 0.021 x 0.025 was inserted into the slot of the miniscrew; the wire supported a temporary prosthetic tooth. 

By means of a stailess steel ligature (0.012inch) the wire was ligated tightly to the bracket-like head of the miniscrew. The head was covered with flowable composite (Tetric EvoFlow, Ivoclear Vivadent, Casalecchio di Reno -Bologna-, Italia) for comfort reasons. The patient was instructed in using chloirexidine spray, three times a day for ten days after the miniscrew placement..

An upper fixed retainer was placed on elements 1.3-1.2-1.1 and on 2.3-2.4. The patient was instructed in daily flossing between the prosthetic tooth and the mucosa, to avoid gingival inflammation.

A clinical examination was performed after 6 months.

A clinical examination and a new CBCT control was performed after twelve months (T1) to evaluate the effectiveness of the study.

Results

The strain generated between the miniscrew and the surrounding bone resulted in increased bone turnover adjacent to the minisrew. 

The patient is satisfied from the aesthetic point of view.

The patient is satisfied from the functional point of view.

The six month clinical follow-up demonstrates no mobility of the miniscrew and no inflammation of the surrounding soft tissues.

The twelve month clinical follow-up demonstrates no mobility of the miniscrew and no inflammation of the surrounding soft tissues.

The twelve month CBCT follow-up demonstrates also the maintenance of the height and the thickness of the alveolare bone.

Conclusions

The mechanical stimulation of the alveolar bone during the chewing processes is essential to maintain height and thickness; the lack of load determines an irreversible reabsorption of the bone. 

It is likely that the strain generated between the mini- implant and the surrounding bone resulted in increased bone turnover adjacent to the mini-implants. 

The method described in this case report is a concrete clinical solution that allows to rehabilitate the partially edentulous patient with a fixed prosthesis, maintaining bone density in the area adjacent to the orthodontic miniscrew while maintaining acceptable esthetics and function.

After twelve months the height and thickness of the alveolar bone was maintained.

Clinical significance: semipermanent replacement of missing teeth (agenesis) by orthodontic miniscrews, in growing patients, can guarantee a good aesthetic, can act as a space maintainer and can potentially counteract the reabsorption of the alveolar bone in a growing patient.