Lingual orthodontics

Clinical case performed employing fixed lingual orthodontic therapy without brackets

Dr. Anna Mariniello

 

Lingual orthodontics rises from the need to satisfy the request, usually from adult patients, for a non visible treatment. This request can be fulfilled neither with a treatment employing porcelain buccal brackets nor with transparent trays (e.g. Invisalign). Both these therapies, although more aesthetically pleasant than metal buccal brackets, are not invisible: the only invisible option is lingual orthodontics.

Lingual orthodontics using brackets, despite the improvement of the brackets design over the years, can cause phonetic problems and tongue decubitus. Moreover the downsizing of the brackets in order to reduce the discomfort sometimes makes it difficult to control dental rotations and torque. This problem has only recently been overcome by Prof. Aldo Macchi’s i-TTR brackets which allow an accurate control of these parameters, as well. Prof. Macchi was also the first to perform, in the early nineties, lingual orthodontic treatments without brackets employing superelastic wires bonded on the lingual surface of the teeth.

This treatment was first carried out on patients who showed a relapse of misalignment after a previous therapy with brackets, using both the buccal and the lingual techniques. The aim was to solve the relapse avoiding a second treatment with brackets and to offer a completely invisible and comfortable solution. The subsequent step was to treat much harder cases and in patients undergoing a therapy for the first time.

The lingual therapy without brackets, subsequently performed by other authors, as well, is both invisible and extremely comfortable. Most patients who undergo lingual therapy without brackets after having undergone lingual therapy with brackets state that in the therapy without brackets they had a lot less nuisances or none at all. The phonetic alterations are hardly ever present and, when present, generally disappear in a few hours.

 

Tools employed and clinical procedure

In order to perform a lingual treatment without brackets the dentist will use wires that will be modelled, activated and bonded directly on the teeth employing fluid composite. Different kinds of wires will be used according to the different kinds of needed movements.

For example, Ni-Ti wires can be used to align a sector while steel wires (e.g. 16-22, 18-22, 17-25, etc) will be used to make stabilizing sectionals. 0.175 inches thick interweaved steel wires, commonly used to make passive retainers, can also be used to achieve an alignment.

These wires are modelled with first and second order bends and activated (active retainers) before being bonded on the lingual surface of the teeth. For example, step bends make derotations of the teeth as well as solving small crowdings (interproximal margins overlapping for less than 2mm) possible.

Second order bends, such as vertical U loops are added for more severe crowdings: the bends are closed for 2 mm during the bonding phase so that the elastic return of the wire makes enough space for the dental alignment. The wire can be activated to obtain both a horizontal and a vertical shift.

Before bonding the previously shaped wire (this operation can also be performed on the chalk mould by novices) the teeth are either cleaned with a small rubber wheel or brushed with a toothbrush. The lingual surfaces where the wire is to be bonded are first etched for 30 seconds with orthophosphoric acid, then the adhesive is applied and polymerized (from 5 to 30 seconds depending on the lamp used).

The retainer is bonded using medium viscosity fluid composite and covering the wire with a layer about 2 mm thick. The bonding sequence is another important element for the good outcome of the treatment using active retainers. In general it is necessary to bond first the teeth closer to the wire or the ones that are to be moved less. It is also important to keep the horizontal plane of the wire not to add unwanted intrusion or extrusion forces.

The patient treated with the active retainers is checked every 3-4 weeks and the retainers are reactivated. This is done detaching the wire from 1 or more teeth that are to be moved and performing the activations (such as adding step bends, expanding the previously shaped loops, bending the wire in buccal-lingual sense, etc.).

The detachment of the wire is obtained using a diamond bur at low RPM and under irrigation until almost all the composite covering the wire is worn. In order not to damage the wire the last layer of composite is not worn down with the bur and the wire is detached using a probe as a lever. After activating the retainer the layer of composite left on the tooth is coarsened with a diamond bur, this time without irrigation (this way it is not necessary to etch again), the adhesive is applied and the wire is bonded with fluid composite.

 

Clinical Case

A patient came to our observation showing a moderate crowding of the maxillary arch (picture 1).

Pic. 1

An active retainer (picture 2) was applied from 44 to 34, shaped with mesial and distal U loops by the right central and lateral incisors and right canine and a distal U loop by the left canine.

Pic. 2

The retainer was activated bonding lingually the portion of the wire to be bonded on the 41: this determines the development of a force that shifts lingually the 41 and buccally the adjacent teeth. These shifts make the buccal-vestibular alignment possible while the loops make the needed space.

The bonding sequence, another aspect of primary importance for the wire to exert its action, is the following. The 42 is the first to be bonded as it is the most lingualized tooth and the closest to the wire.

Subsequently, the mesial and distal loops on the 41 are closed, it is bonded on elements 31, 32 and 33, keeping the horizontal plane in order not to add unwanted extrusive or intrusive forces. It is then bonded on the 34, closing the loop between the 33 and 34 of about 2 mm. The segment to be bonded on the 41 ran more lingually displaced than this element because of the previous activations: it was subsequently pushed with a utility tool on the 41 and then bonded. Finally, always closing the loops of about 2 mm, the retainer was bonded on the 44 and 43.

The patient was checked approximately every 3 weeks. During every check-up the retainer was detached from the 41, 42, 43 and 44 to activate the loops in expansion (opening them of about 2 mm) and to bend lingually the segment of retainer to be bonded on the 41. A mesial inset bend was subsequently added on the 43 to derotate it.

After approximately 4 months the previous active retainer made up of a single wire was replaced with a series of interweaved wires like the previous one and a TMA wire (picture 3).

Pic. 3

An interweaved wire was bonded from the 31 to the 44, passive on all the teeth but the 43. On the latter a loop and an inset bend were shaped to keep on derotating it. Two segments of passive retainers were bonded in overlay to stop the incisors in the achieved position (a segment bonded on the 41-42 and another one on the 32-31-41).

A further segment of active retainer was bonded on the elements 32-33 and 34, with a loop between the 33 and 34. This segment was activated to shift the 33 buccaly and the 34 lingually, applying the V bend principle: before bonding it, the portions of the wire to be sticked on the elements 34 and 32 ran lingually – as the marks on picture 4 clearly show – in order to draw a V with the apex being by the canine and turned buccally.

Pic. 4

Furthermore a sectional was shaped using a 16-22 TMA wire in order to move the 35 buccally. This sectional was bonded from the 34 to the 36; some loops were also added to increase its elasticity and the section to be bonded on the 35 was bent buccally.

The alignment was achieved in about 6 months and a fixed retainer was put on (picture 5).

Pic. 5

Bibliography

 

1. Macchi A, Cirulli N. "Fixed Active Retainer for Minor Anterior Tooth Movement". Journal of Clinical Orthodontics, 2000.

2.Macchi A, Rania S, Cirulli . "Una proposta per la gestione di disallineamenti anteriori: il mantenitore attivo di contenzione (MAC)". Mondo Ortodontico, 1999.

3.Liou EJW, Chen LIJ, Huang CS. "Nickel-titanium mandibular bonded lingual 3-3 retainer: for permanent retention and solving relapse of mandibular anterior crowding". Am J Orthod Dentofacial Orthop 119:443-9, 2001.

 

4.Musilli M. The Bracketless Fixed Orthodontics: nine years of clinical Experimentation. Prog in Orthod 9:72-91, 2008.

 

5.Mariniello A, Cozzolino F. Lingual active retainers to achieve teeth levelling in orthodontics: case series. International Dentistry SA Vol 10 N 5, pag. 24-29, 2008.

For information:

anna.mariniello@libero.it

PORCELAIN VENEERS

MINIMALLY INVASIVE AESTETHIC REHABILITATION OF THE ANTERIOR SECTORS WITH PORCELAIN VENEERS

Dr. Fabio Cozzolino

Dr. Roberto Sorrentino

Dental Technician: Vincenzo Mutone

A female patient, aged 33, needed a functional and aesthetic improvement of the maxillary anterior region previously restored with composite veneers. The chair-side examination showed a marked discoloration of the restorations and an evident and generalized wear of the incisal edges of the anterior sectors of both the maxillary and mandibular jaws.

After explaining the different therapeutic options to the patient, it was decided to build-up 6 feldspatic porcelain veneers to restore elements 11, 12, 13, 21, 22 and 23. Moreover, it was planned to lengthen the incisal margins, in order to improve aesthetics, restore a correct protrusive function and optimize both the overjet and the overbite.

Evaluation of occlusal parameters is of primary importance for long term success of porcelain veneers. It is particularly important to assess the centric relation and protrusion in order to decide if and up to what point extending the palatal tooth preparation. In fact, the centric contacts have to be placed on porcelain, in order to avoid tensive stresses on the adhesive interface between the dental tissues and the restoration during protrusion.

An alginate impression was taken in order to make a diagnostic model to allow the dental technician to make a mock up. The mock-up is a diagnostic aid useful to decide, together with the patient, shape, length and colour of the restorations.

Dental laboratory procedures

After receiving the alginate impression, some diagnostic models were made in the lab: the models were subsequently waxed-up to decide dimensions and volumes of the final restorations.

It is worth remembering that such parameters are dependent on the information received from the clinician. The dentist, in fact, will provide us with all the models alongside with centric, lateral and protrusive waxes – essential to make anterior guides – and specific pictures with detailed information on the anatomy and dynamics of facial and lip expressions and smile. All these data will let us make aesthetic and functional assessments useful to choose shape and to restore the length of the incisal margins – anatomical characteristics that, in this case, needed correction because of the presence of old and inadequate composite restorations.

After completing the wax-up, we will go on to the subsequent making of the mock-up, test and control bench of our lab planning, that will provide us, while testing on the patient, all the information needed to make first the temporary and then the final restoration.

The great attention paid during the diagnostic phase is of primary importance to make our usual prosthetic restorations; it becomes even greater when the prosthetic option chosen is to make feldspatic veneers: their making, in fact, leaves no room for adjustments and improvised and offhand solutions that would impair the final result.

Clinical Part

The mock-up is fit intraorally by simply applying it on the elements to be restored, without any fixing aid. Then the optimal length of the incisal margins is set and marked with black ink in order to have a clear visual contrast and to check the correct morphology of subsequent restorations. Once the correct length is set, it is possible to remove the part marked in black with rotary instruments in order to give the patient an idea of the forthcoming tooth morphology.

Dental laboratory procedures

The temporary restoration will be made after trying the mock up: this trial can provide further information to make it. The temporary restoration, made of acrylic resin, will be built on a model upon which we will have already done some pre-filing adjustments: these are made using silicone guide masks obtained from the waxing and the mock-up, that may be modified, as in this case, after the trial.

Clinical part

Before performing the dental preparations, we inserted intrasulcularly a multi-interweaved retraction chord for each dental element. Afterwards the preparations were made using a diamond, cylindrical dental drill with a round-edged, coarse-grained bur (0.14 of diameter) put up on a multiplier. A diamond, extra fine-grained dental drill with the same morphology was subsequently used to refine preparation geometries; it is possible to use, where necessary, an Arkansas stone to polish and regularize surfaces.

The preparations were made with a vestibular depth of about 0.7 mm, checked sinking the drill for half of its length during the preparation. We made palatal chamfer preparations extending for 2 mm coronally to the incisal margin on the palatal surface.

When clinical conditions allow it, this geometry of preparation may prove to be better than a window preparation limited to the buccal surface for a number of reasons:

• limited stress of the adhesive interface during protrusive function;
• possibility for the dental technician to deal at best with incisal transparencies of the restorations, without the necessity to mask residual dental tissue on the edge;
• univocal positioning of the restorations and reaching rock bottom during cementation.

Previous composite restorations present on the elements to be restored were completely removed in the interproximal zones to ensure a correct prosthetic seal. On the contrary, on vestibular surfaces non infiltrated areas of composite were left in place in case their removal could have caused structural weakening of the dental elements. Present day literature agrees in stating that the presence of a composite surface equal or inferior to 30% of the whole adhesive surface does not represent a risk factor for the cementation of porcelain veneers.

The remaining composite can be either sandblasted intraorally or simply cleaned out and coarsened to help the subsequent bonding procedures.

Interproximal spaces were opened using a metallic abrasive strip on the sides of the enamel; this procedure helps in creating correct contact areas.

After finishing the dental preparations, a two-phase polyether impression was taken with a low-viscosity material injected intraorally on the preparations and a medium-viscosity material in the impression tray. Finally intermaxillary relations were recorded using centric wax on dental preparations.

Afterwards, the previously made temporary restoration was rebased intraorally with self-polymerizing acrylic resin. This temporary restoration was designed by joining all front elements in order to improve retention of the prosthesis, since porcelain veneers are restorations without primary retention. Once done, the temporary restoration was fixed intraorally with fluid composite, without etching the dental tissues.

Dental laboratory procedures

Making feldspatic porcelain veneers requires us to make several test models: master models in chalk and duplicate models in refractory material (coating). The coating used for refractory duplicates must have specific features needed for ceramic cooking.

• Excellent possibility to reproduce details
• Sufficient hardness during manipulation phases
• Possibility to dispose of polluting waste during degasification phase
• Expansion coefficient (C.T.E.) compatible with the one of the used ceramics
• Ease of removal of the veneers after their completion

Once the model and the refractory duplicates are finished, first we will proceed to degasification, then to make the refractory models waterproof. This procedure consists in coating all the surface that duplicates the prepared zone with a layer of transparent ceramics.

This procedure has got a double function:

the first is to completely isolate the subsequent ceramic layers to be laid, protecting them against the absorbing action of the porous surface of the coating that would cause a constant loss of moisture during the phases of stratification;

the second is to create a peripheral contour zone of transparent ceramic mass that will hide more easily the transition zones between restoration and preparation (lens effect).

We will finally go on to simplified stratification, at the end of which, after verifying intraoral aesthetics, it will be possible to free ceramics from the refractory models, to check contact points on master models and to send them to the dental office for cementation.

Clinical part

7 days after putting the temporary restoration in place, we checked colour and aesthetics of the veneers. They were made of feldspatic ceramics, since it provides excellent aesthetics and can be etched, while all-ceramic alumina and zirconia based ceramics cannot be chemically etched. Use of an etching agent on feldspatic ceramics determines the creation of superficial cavitations which increase micromechanical retention of the restorations. Before getting to the dental office, the restorations were sandblasted in the lab.

The following step was cementation using a dedicated resinous dual cement.

The operative area was isolated with a rubber dam without clamps: the edges of the dam sheet were invaginated intrasulcularly using a multi-interweaved retraction chord around every dental element.

This chord is also useful to help removal of excess cement.

Cement colour was chosen using two water-soluble test pastes put inside the veneers covering elements 11 and 21: on element 11 we used a “clear” (transparent) tone, while on element 21 we used a “universal” tone (universal). In agreement with the patient, we chose to use the “universal” tone for cementation.

Thanks to its being completely water-soluble, it is possible to dispose eventual paste waste with a simple rinse and drying.

Following the protocol, we used an etching agent for 10 seconds on dental elements and 5 seconds on the internal surfaces of the veneers. Once rinsed and dried, internal surfaces of the restorations were conditioned with a ceramic primer.

Finally, the six veneers were cemented and the usual operations of removal of excess cement and, where necessary, refining and polishing of the edges using small rubber wheels for ceramics were carried out.

Particular care was dedicated to centric, protrusive and lateral occlusive control.

BEFORE

AFTER

BEFORE

AFTER

It is advisable not to use toothpastes containing fluorine or fluorinated agents for the 2 weeks prior to the cementation, in order to avoid a hyper-mineralization of the dental tissue that may interfere with the sticking.

Bibliography

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3. Wakiaga J, Brunton P, Silikas N, Glenny AM.
   Direct versus indirect veneer restorations for intrinsic dental stains.
   Cochrane Database Syst Rev. 2004;(1):CD004347. Review.
   
4. Strassler HE.
   Minimally invasive porcelain veneers: indications for a conservative esthetic dentistry treatment modality.
   Gen Dent. 2007 Nov;55(7):686-94; quiz 695-6, 712.
   
5. Smales RJ, Etemadi S.
   Long-term survival of porcelain laminate veneers using two preparation designs: a retrospective study.
   Int J Prosthodont. 2004 May-Jun;17(3):323-6.
   
6. Zarone F, Epifania E, Leone G, Sorrentino R, Ferrari M.
   Dynamometric assessment of the mechanical resistance of porcelain veneers related to tooth preparation: a comparison between two techniques.
   J Prosthet Dent. 2006 May;95(5):354-63.
   
7. Peumans M, De Munck J, Fieuws S, Lambrechts P, Vanherle G, Van Meerbeek B.
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8. Magne P, Belser UC.
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9. Zarone F, Apicella D, Sorrentino R, Ferro V, Aversa R, Apicella A.
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For information:

Mr. Vincenzo Mutone

Mr. Mutone was born on January 20^th, 1965 and obtained his qualification as a dental technician in Naples IPSIA “Casanova”.

He holds a lab since 1983.

He took part in many courses in Italy and abroad among which some with Klaus Muetherties and Willi Geller, from whom he learnt his practical teaching and aesthetic philosophy attending many times his lab in Zurich (CH). He was business partner and co-owner of the Oral-Design 2 lab along with Mr. Giuseppe Zuppardi in the years 1994-96. When this experience was over he met professionally Mr. Atoshi Aoshima, who led him to appreciate Japanese aesthetic school. After this experience he started another project that led him to make a systematics for ceramic masses multistratification for the Noritake Kizai, LTD company (Japan).

In the last decade he has held conferences and communications on metal ceramics and aesthetics in many national and international meetings.

Today he focuses particularly on prosthesis implant and aesthetics using modern materials such as zirconia and CAD-CAM methods. He is also taking part in projects that aim to carry out and spread implantology based on computer planning with immediate function application and in the making of a multistratification system on zirconia oxide structures.

Website: www.vincenzomutone.it

Email: vincenzomutone@virgilio.it

Dr Fabio Cozzolino

fabio.cozzolino@fastwebnet.it