7. Acute and

7. Acute and chronic superficial dental caries: pathomorphology, clinic, diagnosis, differential diagnosis, treatment. Acute and chronic medium dental caries: pathomorphology, clinic, diagnosis, differential diagnosis, treatment.

CARIES OF ENAMEL

Macroscopic Changes of Enamel

On smooth surfaces. 

On smooth enamel surfaces, the earliest visible changes are usually manifested as a loss of translucency, resulting in an opaque chalky white lesion in location where caries progressed most probably are becoming arrested, discoloured pigmentation of the enamel may be seen. Smooth surface lesions when sectioned longitudinally are cone shaped with the apex  directed towards the dentin (Figs 30.17, 30.18).

Pit and fissure caries. 

Occlusal fissures are deep invagination of enamel, they can be extremely diverse in shape and size and have been shown as broad or narrow funnels, constricted hour glasses, multiple invaginations with inverted shape.

 

FIGURE 30-17  Figure depicting progression of mineral loss in relation to time.

 

FIGURE 30-18  Smooth surface caries.

 

Classification of fissure morphology is as follows (see Fig. 39.1):

a.  ‘Y’-shaped divisions (5–10%).

b.  ‘V’ type-wide at top and gradually narrowing towards the bottom (30–35%).

c.  ‘U’ type, almost the same width from top to bottom (12–15%).

d.  ‘I’ type, and extremely narrow slit (18–20%).

e.  ‘IK’ type, extremely narrow slit with a larger space at bottom (24–26%).

f.   Other types (7–9%).

Several morphological variations may be found along the length of the individual occlusal fissure as a result it is not always possible to classify a tooth as having a particular type occlusal morphology. Frequently, fissures having a broad base give rise to several pits, which when sectioned, look like inverted ‘Ys’. Many teeth have areas at the base of the fissures where a very thin enamel covers underlying dentin.

Carious lesion more often starts at both sides of the fissure wall rather than at the base, penetrating nearly perpendicularly towards the dentinoenamel junction. In newly erupted teeth, brown stain or discoloured lesion is indicative of underlying decay, whereas in older individuals the lesions may be arrested or remineralised areas. This lesion is commonly described as cone shaped with the base directed towards the dentin and apex towards the enamel surface. Later these macroscopic changes of the enamel in initial caries proceed cavitation and occur without apparent break in the enamel surface.

Microscopic Changes of Carious Enamel

Under microscope, the enamel caries (initial caries) shows four zones, starting from the inner advancing front of the lesion. The zones are:

1.  Translucent zone

2.  Dark zone

3.  Body of the lesion

4.  Surface layer.

There is no sudden or dramatic change from zone to zone but there is a gradual series of changes within the lesion (Figs 30.20A, B). Furthermore, all zones may not be visible by polarized light microscopy.

Zone 1: translucent zone.  The translucent zone of  enamel caries is not seen in all lesions, but when it is present it lies at the advancing front of the lesion and is the first recognizable alteration from the normal enamel. It is more porous than sound enamel, the pores having been created by the demineralization process. Sound enamel has a pore volume of about 0.1%, the translucent zone, however, has a pore volume of approximately 1%. The pores are probably located at junctional sites such as prism borders, cross-striations or along the striae of Retzius. Once these areas are filled with quinoline, structural markings are lost, due to penetration of the quinoline, which has an identical refractive index to that of enamel apatite giving translucent appearance.

Zone 2: dark zone.  The dark zone is the most common feature of the carious lesion and it is the 2nd zone of alteration from normal enamel. It lies just superficial to the translucent zone and appears dark when the ground section is placed in quinoline. This zone is more porous than translucent zone, with a pore volume of 2–4%. It is shown that in this zone the pores are of varying sizes, large and small. Quinoline is a large molecule and cannot enter the small pores, which remain filled with air, giving a dark appearance. These small pores could represent areas of repair where mineral has been re-deposited or they may have been created by demineralization that is by an opening up of sites not previously attacked.

Zone 3: body of the lesion.  The body of the lesion comprises the largest proportion of carious enamel in the small lesion. This zone lies superficial to dark zone and deep to the relatively unaffected surface layer of the lesion. The maximum amount of mineral loss is found in this zone. In longitudinal section with quinoline in polarized light microscopy, the area appears translucent and the stria of Retzius may be well marked. When examined in ground section in water, the water molecules enter the pores in the tissue and since the refractive index of water (1.3) is different to that of enamel (1.62), the area appears dark. The pore volume of this region is 5% at its periphery, increasing to 25% or more in the centre.

Zone 4: surface zone.  The surface layer ranges between 30–100 mm thick and it is thinner in active lesions and thicker in inactive carious lesions. This zone is most clearly seen in polarized light microscope when the section is in water, where it appears as a relatively unaffected area superficial to the body of the lesion. The zone has a pore volume of 1% but if the lesion progresses, the surface layer is eventually destroyed and a cavity forms.

DENTINAL CARIES

Macroscopic Changes of Dentin

Dentin is the hard portion of the tooth that is covered by enamel on the crown and cementum on the root. The development and progression of caries in dentin is different from progression in the overlying enamel because of structural differences of dentin. Dentin contains much less mineral and possesses microscopic tubules that provide the pathway for the ingress of acids and egress of mineral. The dentinoenamel junction (DEJ) has the least resistance to caries attack, hence allows for rapid lateral spreading once caries has penetrated the enamel. Because of this characteristics, dentinal caries is ‘V’ shaped or cone shaped in cross-section with a wide base at the DEJ and the apex directed pulpally.

Defense Reactions of Pulp-Dentin Complex

Histopathology. 

Caries advances more rapidly in dentin than in enamel because dentin provides much less resistance to acid attack because of less mineralized content. Caries in dentin produces variety of responses including sensitivity, pain, demineralization and remineralization. Episodes of short duration pain may be felt occasionally during earlier stages of dentin caries. These pains are due to stimulation of pulp tissue by movement of fluid through dentinal tubules that have been exposed to the oral environment by cavitation. Once bacterial invasion of dentin is near to the pulp, toxins and few bacteria enter the pulp resulting in inflammation of the pulpal tissue. Initial pulpal inflammation is thought to be evident clinically by production of sharp pain (for few seconds) in response to a thermal stimulus. The degree of inflammatory response depends on the rapidity of caries. If dentinal sclerosis occurs, injurious agents will have reduced or no access to the pulp attack.

The pulp-dentin complex reacts to caries attack by attempting to initiate remineralization and blocking off the open tissues. This reaction results from odonto-blastic activity. The dentin can react defensively through repair to low and moderate intensity caries attack as long as pulp remains vital and has an adequate blood supply. In slowly advancing caries vital pulp can repair demineralised dentin by remineralization of the intertubular dentin and by opposition of peritubular dentin.

Dentin responds to the stimulus of its caries demineralization episode by deposition of crystalline material in both the lumen of tubules and intertubular dentin of affected dentin in front of the infected dentin portion of the lesion. These hypermineralised or repaired areas may be seen as zones of increased porosity in radiographs.

A short painful response to cold suggests reversible pulpitis or pulpal hyperaemia. When the pulp becomes more severely inflamed, thermal stimulus will produce pain even after termination of stimulus typically for longer duration. This suggests irreversible pulpitis and the pulp is unlikely to recover even after removing caries.  In such situations, pulp extirpation and root canal treatment are necessary.

Tubular Sclerosis within the Dentin

Tubular sclerosis within the dentin is a process in which minerals are deposited within the lumina of the dentinal tubules. It is also called translucent zone. It represents an area of increased mineral content. Dentin which has more mineral content thaormal dentin is termed as ‘sclerotic dentin’ (Fig. 30.21).

FIGURE 30-21  Sclerosis dentin.

 

Sclerotic  dentin formation occurs ahead of the demineralization front of a slowly advancing lesion and may be seen under an old restoration. Sclerotic dentin is usually shiny and discoloured but feels hard to the explorer’s tip (Fig. 30.20). More intense caries activity results in bacterial invasion of the dentin. The infected dentin contains a wide variety of pathogenic materials, including high levels of acids, hydrolytic enzymes, bacteria and bacterial cellular debris. This material can cause degeneration and death of the odontoblasts as well as mild inflammation of the pulp. These dead empty tubules are termed as ‘dead tracts’.

 

FIGURE 30-22  Reactionary dentin.

 

The pulp may be irritated sufficiently from high acid levels or bacterial enzyme production to cause the formation of replacement odontoblasts (secondary odontoblasts).

Reactionary Dentin (Reparative Dentin)

Reactionary dentin is a layer of dentin formed at the interference between the dentin and pulp. It is formed in response to stimulus acting further peripherally and its distribution is limited to the area beneath the stimulus. It provides extra protection for the odontoblasts and other cells of the pulp by increasing the distance between them and the injurious stimulus (Figs 30.22A, B). These cells produce repairable dentin (reactionary dentin) on affected portion of the pulpal wall. Reparative dentin is very effective barrier to diffusion of material through the tubules and is an important step in dentin repair. The success of dentinal reparative responses, either by remineralization of intertubular dentin and opposition of peritubular dentin or by reparative dentin, depends on the severity of caries attack and ability of the pulp to respond. The blood supply of the pulp could be the most important limiting factor to the pulpal responses.

Inflammation of Pulp

The third level of dentinal response is severe irritation, like acute and rapidly advancing caries with very high levels of acid production, overpowers dentinal responses and results in infection, abscess and death of the pulp. The inflammation of the pulp is called pulpitis. It may be acute or chronic, and it is the vascular response of the pulp tissue to injury.

Zones of Dentinal Caries

Zone 1: Normal dentin.  The deepest area is normal dentin, which has tubules with odontoblastic process that are smooth and no crystals are in the lumen. There are no bacteria in the tubules. Stimulation of dentin by osmotic gradient (from applied sucrose or salt), a bur, a dragging instrument or desiccation from heat or air, produces a sharp pain.

Zone 2: Subtransparent dentin (zone of demineralization).  Subtransparent zone is seeext to normal dentin. This is the zone of demineralization of the intertubular dentin and initial formation of very fine crystals in the tubular lumen at the advancing front. There are no bacterial area found in this zone also. The dentin in this zone is capable of remineralization.

Zone 3: Transparent dentin.  This zone of carious dentin is softer thaormal dentin and shows further loss of mineral from the intertubular dentin. No bacteria are present in this zone either. Stimulation of this region produces pain. Collagen (organic) content of the dentin is intact, which serves as a template for remineralization of the intertubular dentin. Thus, this region remains capable of self-repair provided the pulp remains vital.

Zone 4: Turbid dentin.  Turbid dentin is the zone of bacterial invasion and is marked by widening and distortion of the dentinal tubules, which are filled with bacteria. Less mineral is present in this zone and collagen in this zone will not self-repair. This zone cannot be remineralized and must be removed before restoration.

Zone 5: Infected dentin.  The outermost zone, protected dentin, consists of decomposed dentin that is teeming with bacteria. There is no recognizable structure to the dentin, and collagen and mineral seem to be absent. Removal of infected dentin is essential to sound, successful restorative procedures as well as prevention of spreading the infection.

Advanced Carious Lesions

Caries advancement in dentin proceeds through three changes:

 I. Weak organic acid demineralizes the dentin

 II.  The organic material of the dentin, particularly collagen, degenerates and dissolves

 III.  The loss of structural integrity is followed by invasion of bacteria.

Increasing frequent demineralization of the body of the enamel lesion over a period of time results in weakening and eventual collapse of the surface covering. This results in cavitation and provides an even more protective and retentive zone for the cariogenic plaque, thus helps in accelerating the caries progression.

Affected Dentin: This is softened, demineralised dentin that is not yet invaded by bacteria (zones 2 and 3). It is vital and no need to remove this dentin as it can be repaired.

Infected Dentin:  This is both softened and contaminated with bacteria and dead (zones 4 and 5). It includes the superficial granular necrotic tissue, soft dry and leathery dentin. The zone of decomposed dentin (outer carious dentin) is soft infected dentin, which cannot be remineralized and must be removed during cavity preparation. There is evidence that collagen fibres in the outer layer are irreversibly denatured. In the outer carious dentin, the crosslinks decrease markedly and these biochemical findings suggest that remineralization can occur only in the inner carious dentin where the collagen denaturation is reversible depending on pH. Collagen fibres are believed to be important in the remineralization of carious dentin. The inner layer of carious dentin although partially softened by demineralization contains only few bacteria, and should be preserved, because it can be remineralized.

 

Clinical manifestations of superficial and medium dental caries:

SUPERFICIAL DENTAL CARIES

COMPLAINTS of the patients: Short-termed pain mainly due to sweet, sour irritants; disappear after irritant is removed.

OBJECTIVELY: Defect is localized in the borders of enamel (round, oval- shape), irregular edges of carious cavity. Color of defect doesn’t differ from health enamel. During probing the walls of carious cavity is rough, not painful.

EPT: 2 -6 mcA

Localization of cavities: Fissures, pits, proximal surfaces, occlusal surfaces, cervical parts of teeth’ crown.

Differential diagnosis: Acid necrosis of tooth’ hard tissues, hypoplasia (grooved and pitted) form, erosion, medium dental caries.

 

MEDIUM DENTAL CARIES

COMPLAINTS of the patients: Short-termed pain due to chemical and temperature irritants. Pain disappears after irritants removal.

OBJECTIVELY: Defect is localized in the mantle dentine. Enamel-dentine junction is ruined. During probing: the walls of carious cavity are painful, bottom of the carious cavity is not painful. Carious cavity is fulfilled with a softened dentine.

EPT: 2 -6 mcA

Localization of cavities: Fissures, pits, proximal surfaces, occlusal surfaces, cervical parts of teeth’ crown.

Differential diagnosis: Acid necrosis of tooth’ hard tissues, wedge-shaped defects, deep dental caries.

 

Fig. 1 Schematic diagram of carious cavity in the case of acute (A) and chronic (B) course of dental caries

 

 

Table 2.                                                                              DIFFERENTIAL DIAGNOSIS OF SUPERFICIAL DENTAL CARIES

 

 

 

Table 3.                                                                                         DIFFERENTIAL DIAGNOSIS OF MEDIUM DENTAL CARIES

 

 

PROCEDURES OF DENTAL CARIES TREATMENT 

Conventional methods of carious dentine removal

Access is the surgical term used to describe the procedure for gaining clearance to see and surgically remove caries. This generally involves cutting sufficient enamel and dentine away with burs to provide sufficient access to the caries. High-speed burs are used to remove enamel to expose the softer dentine that is then removed either by high- or slow-speed burs. These burs remove softened dentine along the EDJ to leave a hard, clean dentine  surface. It is particularly important to remove soft caries along the EDJ. Hard dentine contains inconsequential numbers of bacteria preventing lesion progression. Softer dentine contains higher quantities of bacteria which have the potential to continue the tissue destruction. Removal of softened dentine along the EDJ and the placement of  a subsequent restoration arrest the caries process. The need to remove all pulpal caries is not as imperative as that along the EDJ. A balance needs to be achieved by removing sufficient caries to prevent progression and yet conserve the pulp’s vitality. Provided the soft dentine that appears wet is removed, the vitality of the pulp should be protected.

 

However, regardless of cavity localization, there are common stages of dental hard tissues preparation, which are come to:

–                     Anaesthetizing

–                     Disclosure (opening and expansion(extension)) of cavity ( is conducted by using round-shaped, fissures burs, burs that is chosen, should have the size of the working end not bigger than the entrance aperture of this cavity)

–                     Necrectomy

–                     Formation the cavity  for fillings (is conducted with fissures, inverted-cone and cone-shaped burs)

–                     Smoothing the edges of enamel

 

OCCLUSAL RESTORATION

Fig. 2  Occlusal caries in molars – showing pigmented, stained fissures. Cavities are present.

The technique for an occlusal restoration is as follows:

■ Check the occlusion: use articulating paper to mark the occlusal stops (where the upper and lower teeth occlude together). These should be preserved if at all possible during cavity preparation.

■ Consider local analgesia.

■ Shade selection.

■ Isolation: again, ideally a rubber dam should be placed but where this is not possible, cotton wool rolls or dry guards and suction must be used.

■ Cavity preparation: open into the area of caries using a small round or pear-shaped diamond or tungsten carbide bur in the high-speed handpiece. Enough enamel should be removed to give access to the caries in dentine. This caries is then removed with a round stainless steel or tungsten carbide bur in a slow-speed handpiece. It may be necessary to use the high-speed handpiece again if the caries is extensive and more enamel has to be removed to gain access to the carious dentine. Caries should be removed from the enamel–dentine junction first. Check that all the soft dentine has been removed by running a sharp probe along the enamel–dentine junction. Only when this area is clear should caries removal from the floor of the cavity be carried out, either with a round bur in the slow-speed handpiece or with an excavator. When the caries removal stage is complete, the cavity should be reassessed. For cavities that are to be restored with resin composite, it is not necessary to remove unsupported and undermined enamel.

■ Lining: the choice of lining depends on the depth of the cavity. In minimal cavities no lining will be necessary; in medium depth cavities a lining is indicated and this may be achieved using a resin-modified glass ionomer. In very deep cavities a sub-lining of calcium hydroxide should be placed.

■ Dental adhesive: this technique depends on the dental adhesive system being used (see above).

■ Filling the cavity: composite resin should be placed in small increments of less than 2 mm in depth and each increment fully cured. Ideally each increment should touch the minimum number of walls possible to reduce the effects of polymerisation shrinkage.

■ Shaping the occlusal surface: the final increments should be shaped to mimic the shape of the occlusal surface of the tooth. Following final curing, check all the margins with a probe to look for deficiencies or ledges.

■ Polishing: once the rubber dam has been removed  the occlusion should be checked by asking the patient whether the restoration feels high or not and by using articulating paper. Any high spots should be adjusted and the restoration polished (see section on polishing).

 

POSTERIOR PROXIMAL LESIONS

Caries on the proximal surfaces of posterior teeth occurs because plaque can collect cervical to the contact area, resulting in a stagnation area (or plaque trap). The diagnosis of proximal caries requires careful clinical examination of the marginal ridges; this area may appear darker or more opaque than surrounding tooth tissue.

Bitewing radiographs are essential for the diagnosis and assessment of posterior proximal lesions. If the lesion is confined to enamel, as assessed radiographically, then it may be possible to arrest, or even reverse, the progress of the caries. Appropriate dietary advice and interdental cleaning instruction should be given and fluoride, either as an operator-applied varnish or in toothpaste, should be used.

If the lesion has cavitated and spread into dentine then operative intervention will normally be necessary to restore the surface integrity of the tooth. Access to caries on the posterior proximal surfaces may be gained in a number of ways:

■ Through the marginal ridge from the occlusal aspect. The most common technique to gain access to the caries is through the marginal ridge from the occlusal surface of the tooth and this technique will be described in detail.

■ From the occlusal surface (tunnel preparation), preserving the marginal ridge. The tunnel preparation is difficult to execute unless there is a pre-existing occlusal restoration which is removed and access to the proximal caries can be gained from the occlusal cavity, without removing the marginal ridge. This technique is not suitable if there is extensive proximal caries as the marginal ridge will collapse. The main difference between this method is that during preparation contact point is preserved, access to the carious cavity is created from the occlusal surface like a tunnel. This method helps to preserve the most of unmodified tissue. This preparation is recommended to be carried out with turbine handpieces, round-shaped burs with the simultaneous cooling of water.

■ From the buccal (or lingual) aspect. This technique is only suitable where there is no risk of marginal ridge collapse and in situations where resin composite can be used as the restorative material.

■ Directly, if the adjacent tooth is absent.

 

TECHNIQUE FOR POSTERIOR PROXIMAL RESTORATIONS THROUGH THE MARGINAL RIDGE

 

Fig. 3  A carious lesion is present on the distal aspect of the upper first premolar.

 The lesion is shining up through the marginal ridge which shows a pinkish-grey discoloration.

 

■ Local analgesia is usually required.

■ Check occlusion and mark occlusal stops with articulating paper.

■ Ensure effective isolation.

■ Protect adjacent teeth: some operators like to place a matrix band on the adjacent tooth to prevent damage of this tooth during preparation of the box component of the cavity. This is no guarantee that the tooth will not be damaged and care should always be taken in the preparation of proximal cavities to protect the adjacent tooth.

■ Gaining access: access is gained through the marginal ridge using a pear-shaped diamond or tungsten carbide bur in a high-speed handpiece. Start slightly away from the marginal ridge and direct the bur downwards and towards the contact area. The bur should drop down into the caries. Try to leave a thin wall of proximal enamel to protect the adjacent tooth. This can be removed subsequently with gingival margin trimmers. This creates a shape described as a box but it should not be square: it should have round internal line angles and should be wider cervically than occlusally. If there is also occlusal caries then the cavity should be extended into the occlusal fissure (Fig. 13.12). If there is no occlusal caries then the cavity does not need to extend into the fissure (Fig. 13.13).

■ Caries removal: caries should be removed with a round stainless steel or tungsten carbide bur in the slow-speed handpiece. Remove the caries from the enamel dentine junction first before moving to the axial wall (and pulpal floor if the cavity has been extended into the occlusal fissure). An excavator may also be used to remove soft dentine caries. This should result in a cavity that clears the contact area cervically and is wider cervically than occlusally.

■ Retentive features: additional retentive features are only necessary if amalgam is to be used as the restorative material. If the cavity has extended into the

 

occlusal fissure then this will act as a key or dovetail to retain the amalgam and prevent its displacement. If there is no occlusal key and amalgam is to be used, then small grooves should be cut at the junctions between the axial wall and the buccal and lingual walls.

■ Lining: if the cavity is suitably deep to require lining then this should be placed on the pulpal floor and on the axial wall (Fig. 13.14).

■ Matrix band: a matrix band is placed to help retain the restorative material during placement, to give shape to the proximal surface of the restoration and to allow close adaptation of the restorative material to the cavity. The band should be closely adapted to the cervical margin and should be burnished against the adjacent tooth to help formation of a good contact. There are many types of matrix bands and holders, but commonly used ones are:

► Siqveland: this system uses a straight band and the holder and band are removed from the tooth simultaneously. This can sometimes result in removal of part of the newly packed amalgam.

► Tofflemire: this system has the advantage that the holder is removed before the band and this may  prevent removal of the restoration with the band.

►  Circumferential: a number of systems exist that have no retainer/holder. The band is tightened by  a spring mechanism.

►  Ivory: this has a holder which engages into a selection of holes in a metal band. The metal band replaces only one proximal wall and therefore  cannot be used for cavities involving both proximal walls.

■ Wedge: the next stage is to place a wedge at the cervical margin of the band, normally from the buccal aspect. The wedge has several functions:

► It separates the teeth slightly so that when the matrix band is removed there is no space between the adjacent teeth and a tight contact is formed. Wooden wedges swell slightly by absorbing moisture in the mouth so are preferable to plastic wedges.

► It prevents excess material at the cervical area of the cavity forming a ledge.

► It shapes the band at the cervical margin of the tooth.

► It can help retain the band in place.

■ Material placement (amalgam): once the amalgam has been mixed, it starts to set so the operator must work quickly to pack and carve the restoration. The amalgam is transferred in increments from the amalgam carrier to the deepest area of cavity – usually the base of the box. It is condensed first with the wider end of the amalgam condenser and then with the narrower end. It is important to condense the amalgam well to adapt the material to the cavity walls and to reduce porosity. Place the next increment, condense and  continue until the cavity is over-filled. The cavity is over-filled to allow removal of the weak, mercury-rich (γ2) layer that is at the surface of a well-condensed amalgam. Run a straight probe around the inside surface of the matrix band to remove gross excess of amalgam and to start to shape the marginal ridge. Carefully remove the wedge, matrix retainer and band. Check the cervical margin for excess amalgam with a straight probe and remove any excess, either with the probe or an amalgam carving instrument, such as a ½ Hollenbach. Use an instrument designed for carving as it will cut through the amalgam, rather than smearing it (as would be the result if a flat plastic were used).

Using the tooth as a guide, rest the blade of the carver against the tooth and carve through the amalgam to recreate the cuspal shapes of the tooth. Check that the marginal ridge is a similar height to that of the adjacent tooth. Check the occlusion by asking the patient to close gently on the restoration. Listen for the sound of the teeth coming together and any impact on the amalgam. Look for any high spots and adjust. Should the amalgam fracture at this stage, it is better to remove the partially set material and start again, rather than try to add to the fractured amalgam.

■ Material placement (resin composite): dental adhesive should be applied to all the surfaces and margins of the cavity. The first increment of restorative material may be placed either at the base of the box or to form the proximal wall. Light cure for the recommended time, then place the next increment, ensuring that this increment only touches either the buccal or lingual wall but not both. Light cure and continue with incremental packing and curing. Carefully shape the marginal ridge by running a straight probe round the inside of the matrix band and finally recreate the cusp shapes to give the correct occlusal contour. Remove the wedge, matrix holder and band and check cervically for excess material. Check the occlusion by asking the patient and by the use of articulating paper. Shape and polish as required.

ANTERIOR PROXIMAL LESIONS

Caries occurs on the anterior proximal surfaces owing to the accumulation of plaque gingival to the contact area (Fig. 13.16). Detection of these lesions is by direct vision or by transillumination: reflected light in the mouth mirror.

 

The technique for treatment of these lesions is as follows:

■ Gaining access: access to the lesion should be from the palatal or lingual aspect if at all possible, as this will allow preservation of the labial enamel. A small round diamond in the high-speed handpiece is used to drop into the caries.

■ Removal of caries: a round bur in the slow-speed handpiece is used to remove the caries, trying to  preserve the labial enamel. Additional preparation to create a retentive cavity will probably not be necessary as the shape of the carious lesion will result in an undercut cavity. With adhesive restorations, an undercut cavity is unnecessary and amalgam restorations are contraindicated in anterior proximal cavities primarily because of their poor appearance.

■ Lining: a lining should be placed as required. Beware that calcium hydroxide lining materials are opaque and can look unsightly through thin labial enamel.

■ Matrix: a clear cellulose matrix strip should be placed before use of the dental adhesive to prevent bonding the adjacent teeth together. The strip should be placed so that it is cervical to the gingival margin of the cavity.

■ Dental adhesive: apply the adhesive to the cavity and the cavity margins.

■ Material placement: place the resin composite in the cavity in small increments and light cure. After the final increment has been placed, pull the matrix band tight cervically to prevent formation of a ledge, and light cure.

■ Finishing: check the occlusion as before and finish as required.

Fig. 5  Anterior proximal carious lesions in 42 and 43 teeth.

INCISAL EDGE LESIONS

Incisal edge lesions are the result of trauma, failure of a proximal restoration or extensive proximal caries.

Fig. 6  A lesion involving an incisal edge.

The technique for treatment of incisal edge lesions is as follows:

■ Access: access to the lesion is not normally difficult;  the difficulty is creating good bonding potential. A labial bevel or chamfer will increase the area of tooth tissue for bonding and will improve the appearance of the final restoration as it will allow the composite to merge gradually with the tooth, rather than having a butt joint. Palatally, a small shoulder will increase the strength of the restoration in this area of occlusal loading. The lack of cavity walls has the advantage of reduced stress from polymerisation shrinkage.

■ Lining: in trauma cases, direct or indirect pulp capping with setting calcium hydroxide may be necessary.

■ Composite placement: composite can be built up free-hand or by using a matrix. To achieve optimal appearance, composites of different opacity, such as ‘dentine’, ‘body’, ‘enamel’ and translucent, should be built up in incremental layers. The types of available matrices are:

► Custom-made: an impression of the palatal aspect of an intact tooth can be used to aid formation of this aspect of the final restoration. To achieve an intact tooth, a temporary restoration can be placed, or a laboratory wax-up used.

► Preformed: the main types used are clear cellulose strips, incisal corners and complete crown forms.

■ Shaping and finishing: the adjacent teeth may be used as a guide to the shape of the final restoration. Care should be takeot to damage the remaining tooth  tissue in the polishing of incisal edge restorations when it may be difficult to distinguish between tooth and restoration.

 

CERVICAL LESIONS TREATMENT

Lesions occur on the smooth, cervical surfaces owing to enamel and root caries, erosion and abrasion.

Fig. 7  This patient presented with a very neglected mouth; poor oral hygiene, a high-sugar diet and several carious lesions. Before this picture was taken, a disclosing agent was used and the patient was shown how to brush off the plaque. The buccal cavity in the lower premolar is plaque free except where enamel is overhanging the lesion. Removal of this enamel would make it easier to arrest the lesion by plaque control alone.	Fig. 8  Arrested root caries in a plaque-free area, coronal to the gingival margin.	Fig. 9  Root surface caries in an area of plaque stagnation close to the gingival margin.

 

The method of treatment is as follows:

■ Access: this is not normally difficult unless the lesion is on the lingual surface of a molar tooth. The amount of cavity preparation depends on the cause of the lesion: abrasion and erosion lesions may only require the cutting of a bevel and cleaning of the cavity with a pumice and water paste, whereas carious cavities may require access with a high-speed round diamond bur and caries removal with an excavator or round stainless steel slow-speed bur.

■ Material placement: resin composite is generally the material of choice for such restorations but amalgam may be placed in posterior teeth; in difficult, subgingival cavities glass ionomer-based materials may be used. Glass ionomers should be protected with either varnish or an unfilled resin for the first few days after placement to protect them from moisture contamination. The material may be shaped free-hand or with a matrix.

Polishing and finishing restorations

Restorations should be shaped, finished and polished to a high standard for a number of reasons:

■ Patient comfort: a restoration left high will result in pulpitis and pain for the patient. A rough restoration is uncomfortable and possibly painful.

■ Aesthetics: well-polished restorations will reflect the light, minimising the dark appearance of amalgam and making composite restorations more tooth-like.

■ Reduce plaque accumulation: the smoother the restoration, the less plaque will collect, with subsequent effects on caries development.

■ Restoration longevity: a restoration with good marginal finish, appropriate contour and high polish will be less likely to fail and be replaced.

Methods of polishing

Any polishing regime involves starting with a coarse grit and working through to a fine grit. Amalgam restorations should not be polished until at least 24 hours after placement. The following sequence may be used:

■ Amalgam finishing burs (multi-bladed stainless steel burs for the slow-speed handpiece) to develop a smooth surface.

■ Silicone points for final polishing.

For resin composite restorations the procedure is as follows:

■ Superfine diamond burs or multi-bladed tungsten carbide burs in the high-speed handpiece for the removal of ledges and excess material.

■ Superfine diamonds in the slow-speed handpiece may also be used where access is more difficult.

■ For occlusal surfaces, silicone points may be used to give a smooth finish. This may also be achieved with abrasive discs and strips for other surfaces.

■ Finally, a diamond polishing paste will give a high shine to the restoration.

 

Fig. 10   Sequence stages in the treatment of the medium depth cavity; restoration with a light-cured composite.

(a)

(b)

(c)

(a) Cavity prepared in a lower premolar for a posterior composite restoration. Proximal caries and occlusal caries were removed. The occlusal caries was found to be minimal and the cavity was not extended into dentine. Note the flaring of the cavity towards the cervical margin. (b) A thin, contoured, metal matrix in place. The wedge will encourage adaptation at the cervical margin, but a probe should always be used to check that the band is tightly adapted. (c) A spring steel ring is used to further stabilize the matrix and encourage tooth separation. These can be applied using rubber dam forceps or a specially made instrument as shown here. The yellow ‘widget’ helps to keep the rubber dam in place mesially. Strips of the dam or floss could also achieve a similar result.

(d)

(e)

(f)

(d) Side view of matrix holder showing engagement of ring between teeth.       (e) The whole of the cavity is etched with phosphoric acid gel for 20 seconds.       (f) The acid gel is washed away.

(g)

(h)

(i)

(g) Large amounts of water are blown away with an air syringe without drying the tooth. Any remaining water is removed from the cavity using a cotton pledget or large endodontic paper point.     (h) The bonding agent is applied (following manufacturer’s directions).     (i) Gentle and complete solvent evaporation is essential.

(j)

(k)

(l)

(j) The bonding agent is light-cured for 10–20 seconds.     (k) The first portion of composite is placed.     (l) The composite is directed to the floor and one wall of the proximal cavity.

(m)

(n)

(o)

(m) The restoration is cured through the tooth from the same side. This helps to prevent polymerization stress build-up. The second (and any other) increments are then added and cured.   (n) The matrix is removed.   (o) The final increment of composite is contoured as much as possible before it is polymerized. A multi-bladed tungsten carbide finishing bur is used to contour the marginal ridge (note the water spray).

(p)

(q)

(r)

(p) A ‘rugby ball’-shaped fine diamond is used to contour the occlusal anatomy. All high-speed instruments must be used with water spray.   (q) A flexible, abrasive, impregnated disc is used to smooth the occlusal contours.   (r) The interdental area can be gently polished with suitable abrasive strips.

(s)

(t)

(u)

(s) To seal defective margins, which may show up after polishing, the tooth is re-etched for 15 seconds, washed, and dried as before.   (t) Bonding agent is liberally rubbed over the surface, then air-thinned and any solvent evaporated. It is finally light-cured from all directions.   (u) The completed restoration before removing the rubber dam and checking the occlusion.

(v)

(v) Side view showing the rounded proximal contours achievable with soft metal matrices.

 

Information was prepared by Levkiv M.O