Invisible Orthodonthics

Lingual Orthodontics without brackets: mechanics to close spaces

Dr. Anna Mariniello
Dr. Fabio Cozzolino

The aim of this work is to explain how closing the diastemas is possible in an orthodontic lingual approach without brackets.

The suggested procedures are the following:

- Retainers with vertical loops

- Sliding mechanics made with rectangular steel wires

The choice between the two types of devices depends on whether there is a need to change the shape of the arch and solve a misalignment or not. In case there is this need a retainer with loops will be used. If the shape of the arch and the position of the teeth are ideal (in buccal-lingual and occlusive-gingival sense) a sliding mechanics with rectangular steel wires will be made.

Retainers with vertical loops

The spaces are closed shaping vertical loops, e.g. U loops, on a 0.175 inches retainer wire.

Suppose there is the need to close a diastema between two central incisors, the mandibular ones, unlevelled in buccal-lingual sense (B-L). And suppose that the 31 is more lingually displaced than the other dental elements. It is possible to deal with this dental malposition shaping the retainer wire so that it passively adapts to the lingual surface from canine to canine. This wire will be shaped with a U loop between elements 31 and 41 and will be activated with the procedures dealt with in the previous articles (pre-activated retainers).

The loop will be closed of about 2mm (e.g. with a lingual arch plier) to activate the retainer in order to completely close the diastema. In order to activate the wire and achieve the levelling the segment to be bonded on element 41 will be bent lingually and the one to be bonded on the 31 buccally. The bending is achieved holding the first vertical segment of the loop with a plier (e.g. a bird beak plier), holding the second vertical segment of the loop with another one (e.g. a Weingart plier) and applying a torque in B-L sense. It is also possible to activate the retainer and achieve the levelling in other ways, for example making a V fold with the peak heading buccally by the segment of the wire to be bonded on the 31.

At this point the retainer is bonded according to the procedures explained in the previous articles. In the case speculated about, the wire would first be bonded on elements 33, 32, 31 – since the tooth closer to the wire is to be bonded first. Subsequently, opening the loop of about 2 mm, the wire would be bonded on elements 41, 42 and 43.

This device would be checked every 3 weeks and, in case the space is not closed, it would be detached from elements 41, 42 and 43, reactivated (closing the loop and creating an activation to move the 31 buccally, if necessary) and bonded.

After closing the space and accomplishing the alignment in B-L sense, the active retainer would be replaced with a passive one.

The following picture shows an example of spaces closed making loops on a 0.175 inches retainer wire.

Sliding mechanics made with rectangular steel wires

The spaces are closed using a rectangular steel wire (e.g. a 0.16 x 0.16) shaped without creating sharp bends that would increase friction and block the sliding mechanics. Therefore the wire is shaped after the curvature of the arch.

After shaping the wire, the segment to be bonded on the teeth where the sliding mechanics is to be made is isolated making a wax sleeve.

This is done using a spatula heated an a flame and some wax.

The wax sleeve is made by touching repeatedly first the wax and then the wire with the heated spatula.

The part of the wire to be bonded on the teeth that will not be moved is not sealed with wax. That segment of wire, before being bonded, can also be blocked either creating stop bends or making incisions with a small round diamond bur to increase retention after composite application.

The wire is subsequently bonded following the standard procedures and using fluid composite. The composite does not touch the wire thanks to the applied wax: this ensures low friction and the possibility to make the sliding mechanics. The applied wax, on the other hand, will gradually wear down and eventually totally disappear.

After bonding the wire the activation to close the space (or spaces) is carried out by applying an elastic chain. This is applied using metallic bindings and activated of about 50 grams. The traction is renewed once every 3 or 4 weeks until the space is closed. Once it is closed, the teeth can be stopped either using figure-of-eight metallic bindings or making carvings ranging from the composite to the wire with a small round diamond bur and then filling them with adhesive and fluid composite.

Clinical Case

In the following clinical case there is a clear example of sliding mechanics used to close spaces. The patient shows:

- Diastemas in the front sector of the maxillary arch

- Deep bite

- Left molar and canine class II

- Right molar class I and canine class III

The right canine class III is due to the presence of a 3.5 mm. diastema between the 44 and the 43 .

A therapy was carried out to solve the deep bite, close the diastemas and centre the midline.

The option chosen to solve the deep bite was the use of 2 micro-screws on the mandibular arch. These micro-screws were put on the gums adhering between lateral incisors and canines.

The teeth from canine to canine were bound together shaping a sectional with a steel 0.16 x 0.16 wire: the sectional was to passively adapt to the lingual surface of the teeth and was subsequently bonded with fluid composite.

The intrusive force was achieved using elastic chains positioned on the heads of the micro-screws and bonded on the buccal surface of teeth 33 and 43.

Once every 3 weeks the elastic chains were replaced. When the intrusion was achieved, the teeth were blocked shaping some sectionals with a rectangular steel wire, inserting them into the micro-screws and bonding them to the teeth.

After the reduction of the OVB, achieved after 4 months, the spaces on the maxillary arch were closed using sliding mechanics.

Therefore a rectangular 0.16 x 0.16 steel wire was shaped after the arch curvature. It is important not to make sharp bends that would impede the sliding.

The offset modelled between the laterals and the canine creates a stop at this point. If there had been no offset, it would have been enough to bend the endings of the wire by the distal surface of the canines.

The segment to be bonded on central and lateral incisors was sealed making a wax sleeve, as previously explained.

The presence of wax prevents the fluid composite used to bond the wire from touching the wire itself: this reduces friction and allows a correct sliding. This makes it possible to move the teeth keeping torque and tip unchanged. The mechanical retention of the composite on the segment of the wire to be bonded on the canines was increased making incisions with a small round diamond bur.

The activation to close the diastema between the incisors was accomplished binding an elastic chain between the 21 and the 22, activating it in the opening and blocking it with a metallic binding between the 11 and the 12.

After 3 weeks that chain was renewed and after about 40 days the diastema was finally closed.

At this stage some grooves from the composite to the wire were made with a small round diamond bur (the wire itself had superficial incisions).

Afterwards adhesive and fluid composite were put in place to fill the grooves. These procedure makes it possible for the composite to bind to the wire and blocks the sliding mechanics. After blocking the centrals, the laterals are moved mesially following the same procedure.

When the mesial drift of the 22 is achieved, this is blocked using a figure-of-eight metallic binding between the 21 and the 22.

In the meanwhile the mesial drift of the 12 is still active.

When the space between the 11 and the 12 is closed, the wire will be blocked by both laterals creating the grooves between the composite and the wire as previously explained. Stabilizing steel sectionals will be shaped: they will be perfectly passive and clinging to the lingual surface of the lateral maxillary sectors from the canine to the 2^nd molar. Using a vertical U loop the spaces between the canine and the lateral incisor of both sides will be closed drawing the incisors back and normalizing the OVJ.

On the mandibular arch a micro-screw will be positioned between the 1^st and the 2^nd right premolar: it will be used as anchorage to move the right canine distally, obtaining a class I relation. That micro-screw will also be used to move the other dental elements (bound together using a steel sectional) to the right, centring the midline.

For information:

Dr. Fabio Cozzolino

Dr. Anna Mariniello

fabio.cozzolino@fastwebnet.it

anna.mariniello@libero.it

Active retainers to solve anterior misalignments: an innovative lingual orthodontic method without brackets

Dr. Anna Mariniello

The ever-increasing request for orthodontic treatment in adult patients has determined an increase in lingual orthodontics. The request for treatment is often determined by aesthetics and the need to solve misalignments of the anterior region. For this reason a new alignment method using lingually bonded elastic wires has come into being (1-2). These devices, as reported by the patients, are much more comfortable than lingual brackets.

This new lingual device was invented by Prof. Aldo Macchi and Dr. Nunzio Cirulli. In 1999 they published two articles about an innovative lingual method that used an aid they had developed called “Active Stabilization Holder” (MAC, from the Italian “Mantenitore Attivo di Contenzione”). The MAC is a fixed active retainer, made up of a .012 inches Nickel Titanium wire bonded with a light-polymerizing composite resin (1-2) to the teeth adjacent to the ones to be moved.

In 2001 Dr. Eri J. W. Liou published an article where anterior dental overcrowdings were solved using Nickel Titanium wires bonded on the lingual surface of the canines and moved to the lingual surface of the anterior and lateral incisors by means of interdental metallic retainers (3).

The dental alignment method by means of lingual orthodontics without brackets, springing from an association of the elastic properties of the wire and the principles of biomechanics, has undergone subsequent evolutions from its own creators.

This technique was subsequently improved also by Dr. Musilli, who transferred the activations that take place on the arches from the bracket technique (loops, step-bends, v bends, etc.) to lingually bonded active retainers. These retainers are made up of 0.175 inches thick interweaved wire.

The following clinical case was carried out using this procedure.

Clinical case

The patient showed a dental first class malocclusion characterized by a light mandibular overcrowding and a preceding extraction of the 16. In region 23 an implant had been positioned because of the extraction of the included canine.

The mandibular alignment was obtained using an active retainer made up of a 0.175 inches thick interweaved wire.

This retainer was modelled with mesial and distal loops on central and lateral incisors, with an offset bend by the distal margin of the 42. Before bonding the retainer, the loops were opened of about 2 mm. Moreover the wire was stopped with bird beak plier where the mesial loop at the 32 continued on the horizontal segment of the wire to be bonded at the 32. Both the edges of the wire were bent lingually creating a V bend with the top heading buccally.

This activation will provide expansion in the zone 31-32 and will allow for the derotation of the 32. With the same procedure another V bend was modelled distally to the part to be bonded at the 41, right before the distal loop. After cleaning the lingual surface of the teeth, they were etched for 30 seconds. Afterwards the adhesive was put on and polymerized. At first the wire was bonded with fluid composite on the 31, then the mesial and distal loops at the 32 were closed with a utility tool of about 2 mm and the horizontal plane kept with another utility tool or a probe; finally the retainer was bonded on the 33. The segment to be bonded on the 32 was situated more lingually displaced on the distal margin of that element because of the previous V bend: it was drawn near the lingual surface of the 32 and then bonded. With the same procedure, the mesial and distal loops at the 41 and 42 were closed and the retainer bonded on the 42 and 43.

The segment to be bonded on the 41 was situated more lingually displaced on the mesial sector of that element, because of the previous offset activations and V bends: it was moved from the lingual to the buccal side and bonded on that tooth. It is obviously important, during the bonding procedure, not to let the composite flow down on the gums in order to avoid periodontal problems.

With these activations, the more the loops make more room, the more the intercanine diameter, the buccal extension of the mesial margin of the 32, the distal margin of the 41 and the lingual extension of the distal margin of the 42 and 32 increase.

Checkups were carried out every 3 weeks. On each check-up the retainer was removed from the teeth where the activations were to be performed again (32 and 41) removing most of the composite covering the wire with a diamond cylindrical bur put on a multiplier and providing irrigation. Afterwards a leverage movement was made with a probe to remove the retainer. In concrete terms, to avoid any damage to the retainer not all the composite was removed with the bur but the last bit was taken away using the probe as a lever: then, the wire was removed. To bond the retainer again there was no need to etch since there was a thin layer of composite on the teeth. On the other hand, the composite was coarsened with the diamond bur previously used but at lower rpm and without irrigation, cooling with air, creating mechanical micro-retentions. Afterwards the adhesive and the fluid composite to bond the wire were put in place. After 2 months the derotation of the 32 and 42 was complete and it was time to give lingual extension to the 31 and continue the derotation of the 41.

On every check-up (once every 3 weeks) the wire was removed from elements 31 and 41 bending lingually the segment to be bonded on the 31 and shaping the offset bend by the distal margin of the 41. After approximately 4 months the alignment was complete and the active retainer was replaced with a passive one.

On the maxillary arch a palatal micro-screw was positioned between the 14 and 15 by the Resistance Centre (RC) of the 17 to mesialize the 17: this was done considering that this element was rotated in mesial-buccal direction. A power arm was bonded on the palatal surface of the 17 and was linked to the micro-screw by means of an elastic chain.

This system generated a force able to mesialize the 17 derotating it.

As soon as the palatal rotation of the 17 started, it was controlled applying an elastic chain between the 15 and the 17 (the ideal solution would have been to apply a buccal force when the molar was completely derotated).

A 16-16 steel wire was shaped in order to passively adapt to the lingual surface from the 15 to the implant in region 23. The alternative to this stabilizing sectional, in particular if there had been no implant in region 23, would have been to position another buccal micro-screw.

At the moment (12 months later) there is a tip spring on this molar, at the base of the micro-screw, to complete the mesialization of the root.

BIBILIOGRAPHY

1. Macchi A, Rania S, Cirulli N. Una proposta per la gestione di disallineamenti anteriori: il mantenitore attivo di contenzione (MAC). Mondo Ortodontico, 1999; 5: 389-393.

2. Macchi A, Cirulli N. Fixed active retainer for minor anterior tooth movement. Journal of Clinical Orthodontics, 2000; 34: 48-49.

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. American Journal of Orthodontics and Dentofacial Orthopedics, 2001; 119:443-449.

For further info:

Dr. Anna Mariniello

anna.mariniello@libero.it

tel.+39 081 2451805

Dental hyper sensibility

Dr. Natascia Raciti

 

Dentine hypersensitivity represents a dental pathology of relevant clinical interest. It is characterized by pain, usually localized in one or more dental elements presenting a gap of the dentinal tissue, evoked by different stimuli (temperature, tactile, chemical and osmotic) which act in lack of other dental pathologies. Chronic traumas such as friction, abrasion, erosion acting on vital dental elements may remove the enamel or the cement that normally protect dentin causing gaps and consequently the direct contact between external intra-oral milieu and the pulp dental tissue (because of an anatomic variability, in some patients there cannot be a contact at a cervical level between the dental enamel and the cement). Pain can affect every dental element and any patient at any age although female patients age 20- 40 are typically affected (1, 2). Dentine hypersensitivity most frequently affects patients with periodontal diseases (3, 4), and can transitorily appear in patients under deep scaling, root planning, or periodontal surgery therapy (5) and patients undergoing teeth whitening or receiving conservative therapies (6). The role of the bacterial plaque in this disease is however controversial. The plaque accumulates on the radicular surfaces and its demineralizing effect on the dental structure can be associated to the opening of the orifices of the dentinal tubuli(7). According to some investigators patients maintaining a good plaque control have a low risk to develop a dentinal hyper sensitivity (8). On the contrary, many patients presenting gingival recessions together with plaque accumulation, have dental hyper sensitivity symptoms(9,10).

Definition: Brief but intense pain sensation caused by physical or chemical stimuli not induced by other dental pathologies (11).

Etiology: The association between dentinal tubuli and pain is based on the well known Brannstrom's hydrodynamic theory. The application of a stimulus can cause a perturbation of the dentinal fluid contained in the tubuli (contraction, expansion, movement) which mechanically activates baroreceptors of the nerve endings of the dentinal pulp organ (A-D fibres) causing pain. The generation of the potential of action in the intra-dental nerve is responsible for the sense of pain (12, 13). In particular, temperature drop, loss of hydration caused by water jet, evaporation and application of an osmotic stimulus (sugar, acid, salt etc.) may cause the centrifugal movement of the tubular fluid. Therefore, it can activate the nerve endings more efficiently compared to other stimuli (tactile and temperature rise) inducing fluid movement towards the pulpe (14,15). A 75% of patients with dentine hyper sensitivity feel, in fact, pain when in contact with a thermic stimulus (cool) (16)

Initial lesion: the opening of the external end of dentinal tubuli appears when the smear layer or the intra-tubular substance are removed (17) mechanically (abrasion) or chemically (erosion). Acid erosion seems to be the main causal factor(18).

Lesions site: the cervical edge is affected in more than 90% of cases both on the vestibular and the lingual-palatal side (16). The loss of enamel and moreover, a gingival recession are fundamental elements in the etiology of the dental gap (18)).

Prevalence: The significant differences among the populations studied and the investigation methods used by different authors cause a large range of prevalence values (4-57%) (19, 20). The dental hyper sensitivity prevalence ranges from 60 to 98% in patients with a periodontal disease (3). The incidence top is at the end of the third life decade and decreases during the fourth and the fifth decade (1,2), The age dependent reduction of dentinal permeability and nerve sensibility, the secondary dentinal production, the extended use of toothpastes and mouthwashes containing fluorine can in fact occlude the exposed dental tubuli and reduce sensibility (21).

Distribution : superior premolar, first superior molar and superior and inferior incisives are the dental elements frequently involved in the dental hyper sensitivity phenomena (22,23). There seems to be a light predilection for the female sex (22,1,24).

Differential diagnosis:

· caries lesions affecting dentinal tissue

· pulp hyperemia

· cuspids’ fracture

· infiltrated restores

· palatal-gingival ploughs

· dental breaks or chips (25,26)

· elements prosthetically prepared without definitive cements

Clinical diagnosis: the diagnosis may be defined following personal anamnesis collection, clinical and X-ray examination and after exclusion of other pathological conditions (see differential diagnosis). The typical temporary pain which appears after a stimulation of the dental element affected, can be provoked by the operator by using a dental drill or an air stream to register the patient’s personal answer to the disturb severity and to follow it up (11,27).

Symptoms: dentinal hyper sensitivity can be present as an uncomfortable and unpleasant sensation. The pain described by the patient can be defined as soft or intense, vague or specific, intermittent or constant (28).

Risk factors:

· wrong brushing techniques

· wrong inter-dental floss use

· use of highly abrasive toothpastes

· presence of acid materials of external or internal origin in the oral cavity

· chronic traumas due to wrong habits (grinding teeth in stress situations)

· small dental breaks

· dental substance loss in the dental collar presumably associated to near occlusive trauma

· periodontal surgery operations

· dentinal gaps in the dental collar associated to the adherent gingival loss

· defect in the development of enamel and dentin

· broken fillings

· prosthetic preparations (generating gaps of 70000 tubuli per mm2).

Professional therapy: it is a more complex treatment indicated when hyper sensitivity affects one or more dental elements. The following are some substances contained in commercially available products to control dentinal hyper sensitivity:

· fluoride: sodium fluoride made toothpaste or concentrated solution and stannous fluoride in water solution or gel made by glycerin and carboxi-methyl-cellulose reduce the dentinal permeability in vitro (29) perhaps through precipitation of insoluble calcium fluoride on the dentinal surface promoting obliteration of exposed tubuli (7).

· potassium nitrate: potassium ions contained in toothpaste at 5% at low abrasivity or in

bi-adhesive gel at 5% and 10% thanks to their depolarizing effect reduce nerve excitability in animal models (30,31,32).

· oxalates: potassium oxalate at 3% and ferric oxalate at 6.8% reduce dentinal permeability and obliterate tubuli more efficiently in vitro (33,34) than in clinical practice (35).

· calcium phosphate: it occludes in vitro (36,37) dentinal tubuli and it reduces their permeability.

· calcium hydroxide: it occludes dentinal tubuli through a link among calcium ions and high protein free radicals and increases the mineralization level of the exposed dentin. It acts immediately but for a short time, therefore continuous applications are needed (38) and it can irritate the gingival edge (39).

· resin and adhesives: these materials can be used just in case of a specific and localized hyper sensitivity. Even though they act efficiently by a de-sensitization point of view, the risk of molecular broken and consequent exhibition of tubuli is high and represents a limit in the use of these composites (28).

· hydroxynanoapatite: it occludes dentinal tubuli thanks to its ability to create a non reabsorbed precipitate with high affinity for collagen fibrilles. (In our clinical practice the Twin Pro desensitization solution for professional use, seems to be very effective. It is constituted by a solution of soluble salts of potassium (green) which can inhibit the stimulation of nerve fibres through an extended release of potassium ions (chemical action mechanism) and of a solution of soluble salts of calcium and strontium (yellow) responsible for the mechanic occlusion of dentinal tubuli (physical action mechanism).

Alternative procedures:

· ionophoresis together with fluorine administration: thanks to electric current flow which can facilitate the spread of fluoride ions in the tissues, this treatment causes an immediate reduction of the sensitivity. However symptoms appear again after 6 months (40).

·Laser use: Nd.YAG laser irradiation together with the giving of enamels containing fluorine of sodium demonstrate are able to occlude more than 90% of dentinal tubuli (41) such as CO2 laser combined therapy- application of stannous fluorine gel is efficacious in closing the tubuli for a period of about 6 months (42,43)

Home therapy: it is simple, cheap and indicated for treatment of a spread hyper sensitivity. Commercial products used are toothpastes and mouthwashes containing one or more desensitization agents.

· Potassium salts: toothpastes containing potassium nitrate at 5% or potassium clorure at 3,75% are efficacious in the desensitization therapy (44,45)

· Potassium salts and fluorine: toothpastes containing potassium nitrate at 5% and stannous fluoride at 0,45% spread by a paste containing silicium (44,46) guarantees a reduction of dentinal hypersensitivity and also shows in an in vitro research a low hydro conductance and provides a high flow of potassium ions in the dentinal tissue (47).

Role of eccipients: some materials are critical for the determination of how the presence of other substances as sodium monofluoridephosphate, sodium fluoride, tin fluoride and anti plaque agents can compromise the desensitization action of the above mentioned formulations. Some studies on the addition of triclosan anti plaque agents and zinc citrate showed that these materials do not interfere with the efficiency of products containing potassium salts (nitrate and potassium citrate) (45,48).

Prevention: A very important aspect, frequently undervalued by a lot of dentists is the one concerning preventive measures. A valid treatment plan should include the identification and elimination of causal factors such as the assumption of acid substances of external origin by the patient or the presence of internal acids which are in contact with the oral cavity and the brushing trauma. The role of erosive agents in the appearance of the dentinal hyper sensitivity is well known and documented (26,18). External sources of acids (fruit, fruit juice, yogurt, cola, wine) and internal ones (gastric reflux and regurgitation) can cause enamel lesions(erosion), detach the smear layer and open dentinal tubuli. The damage of the dentinal tissue is harder when we associate acid substances to the use of tooth pastes with a high abrasion index (18). The most appropriate recommendations for the patient is not to brush his teeth in the 2 or 3 hours after eating or drinking acid drinks to avoid the damaging erosion and acid-abrasion effect.

Conclusions: The starting point for dentists having to face up with patients with painful symptoms due to dentinal hypersensitivity is to define via anamnestic data collection, the role of some causal factors leading to hyper sensitivity. It is important to identify these factors in order to program a correct plan of treatment including professional and house management strategies and prevention of dentinal hypersensitivity. The patient management affected by hypersensitivity can be based on the use of active materials which drastically reduce dentinal sensitivity and, most importantly, by giving useful instructions concerning the elimination of wrong life habits associated with recurrent dentinal hypersensitivity episodes.

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