6 Restorative dentistry

Chapter 6

Restorative dentistry

Laura Mitchell

David A. Mitchell

Lorna McCaul

Contents


Relevant pages in other chapters Caries diagnosis, p. 26; amalgam, p. 608; resin composite, p. 610; the acid-etch technique, p. 614; dentine adhesive systems, p. 616; glass ionomers, p. 618; cermets, p. 623; cements, p. 624; impression materials, p. 626; casting alloys, p. 630; acid-etch tip, p. 100.



Principal sources and further reading Operative Dentistry. Dental Update. The British Dental Journal. B. G. N. Smith 1997 Planning and Making Crowns and Bridges, Dunitz. P. A. Brunton 2002 Decision Making in Operative Dentistry, Quintessence. J. L. Gutmann et al. 1997 Problem Solving in Endodontics, 3rd edn, Mosby. E. A. M. Kidd et al. 2003 Pickard’s Manual of Operative Dentistry, 8th edn, OUP. S. J. Davies and R. J. Gray 2002 A Clinical Guide to Occlusion, British Dental Association. J. M. Whitworth 2002 Rational Root Canal Treatment in Practice, Quintessence.



To attempt to resolve the problem of caries by preparing and restoring teeth is comparable to trying to resolve the problem of poliomyelitis by manufacturing more attractive and better quality crutches, more quickly and more cheaply.


Treatment planning

A proper treatment plan can only result from a thorough patient assessment, which must include a history, an examination, relevant special tests, and ultimately, a diagnosis.

Under ideal circumstances an integrated treatment plan is formulated for each patient at the start of every course of treatment. Very often, however, the treatment plan will need to be revised in the light of clinical findings as the treatment progresses, e.g. patient cooperation, response to periodontal therapy, investigation of teeth of doubtful prognosis, etc. When dealing with patients with a range of problems it is therefore wise to formulate a treatment plan which has a number of achievable goals, and then on completion of this to reassess the patient to decide on what further treatment is necessary.

Sequence of treatment

This list is obviously an oversimplification but should serve as a general guide to the order in which treatment should be carried out.

1) Relief of pain.
2) Control of active disease and achievement of stability:

OHI, dietary advice, topical fluoride, and initial periodontal therapy;
extraction of unsaveable teeth;
treatment of large and active carious lesions;
consideration of definitive denture design;
remaining simple restorations;
RCT.
3) Reassessment of success of initial treatment, OH, periodontal condition, and prognosis of teeth.
4) Definitive treatment: crowns, bridgework, and dentures.
5) Maintenance and review.

Practical points

The priority of items of treatment must be taken into account when formulating a treatment plan, which may lead to deviations from the scheme described above. For example, in an apprehensive patient it would be more appropriate to complete small restorations before dealing with the large ones.
Explain what the treatment plan involves to the patient and the role they will have to play in controlling their dental disease. Success is dependent upon patient compliance, therefore time spent discussing their expectations, treatment options, time involved, cost implications present and future, and their role in maintenance is never wasted. Equally without such a discussion consent is not by definition informed.
If need to check a medical history with patient’s GMP or refer patient to a specialist, allow sufficient time to elapse before arranging to carry out any treatment that is dependent upon the outcome.
It is important to bear in mind subsequent items on a treatment plan, e.g. the design of a P/- may influence the choice of material and contour of restorations.

For complex cases, several short treatment plans, each ending with a reassessment, are more logical and efficient than one long one that keeps changing.
When formulating a treatment plan group items together into appointments to form a visit plan. Decide how long you will need for each visit.
Although it is usually advantageous to complete as much work as possible at each visit, in a proportion of patients (or if carried to an extreme, in any patient) this can be counter-productive. If in doubt about how much treatment to do at a visit, discuss this with the patient.
Regularly reinforce the OH throughout the treatment (e.g. whilst waiting for LA to take).
Record-keeping is very important. At the end of each visit carefully note what has been done and the materials used (including sizes and shades). Cross that item off the treatment plan and adjust the patient’s chart. Note what is to be done next visit: this will save time.
It is important to recognize your own limitations, and where appropriate refer a patient for advice or treatment.

Stabilization or caries control

In patients with multiple carious lesions it may take several weeks/months to complete the permanent restorations necessary to secure OH. In these cases it may be advisable to prevent any symptomless large lesions increasing in size by placing temporary dressings. The cavities should be rendered caries-free at the margins, and temporarily restored with a strong cement, e.g. traditional or resin-modified GI cement.

Dental pain

When a patient attends the surgery and complains of toothache, pain may be arising from a variety of different structures and may be classified as follows:

Pulpal pain
Periapical/periradicular pain.
Non-dental pain.

Dental pain can be very difficult to diagnose, and the clinician must first gather as much information as possible from the history, clinical and radiographic examinations, and other special tests (see Chapter 1).

Pulpal pain

The pulp may be subject to a wide variety of insults, e.g. bacterial, thermal, chemical, traumatic, the effects of which are cumulative and can ultimately lead to inflammation in the pulp (pulpitis) and pain. The dental pulp does not contain any proprioceptive nerve endings, therefore a characteristic of pulpal pain is that the patient is unable to localize the affected tooth. The ability of the pulp to recover from injury depends upon its blood supply, not the nerve supply, which must be borne in mind when vitality (sensibility) testing is carried out (p. 14).1 It is impossible to reliably achieve an accurate ∆ of the state of the pulp on clinical grounds alone; the only 100% accurate method is histological section.

Although numerous classifications of pulpal disease exist, only a limited number of clinical diagnostic situations require identification before effective treatment can be given.

Reversible pulpitis

Symptoms

Fleeting sensitivity/pain to hot, cold or sweet with immediate onset. Pain is usually sharp and may be difficult to locate. Quickly subsides after removal of the stimulus.

Signs

Exaggerated response to pulp testing. Carious cavity/leaking restoration.

Rx

Remove any caries present and place a sedative dressing (e.g. ZOE) or permanent restoration with suitable pulp protection.

Irreversible pulpitis

Symptoms

Spontaneous pain which may last several hours, be worse at night, and is often pulsatile in nature. Pain is elicited by hot and cold at first, but in later stages heat is more significant and cold may actually ease symptoms. A characteristic feature is that the pain remains after the removal of the stimulus. Localization of pain may be difficult initially, but as the inflammation spreads to the periapical tissues the tooth will become more sensitive to pressure.

Signs

Application of heat (e.g. warm GP) elicits pain. Affected tooth may give no or a reduced response to electric pulp tester. In later stages may become TTP.

Rx

Extirpation of the pulp and RCT is the treatment of choice (assuming the tooth is to be saved). If time is short or if anaesthesia proves elusive then removal of the coronal pulp and a Ledermix® dressing can often control the symptoms until the remaining pulp can be extirpated under LA at the next appointment.1

Dentine hypersensitivity

This is pain arising from exposed dentine in response to a thermal, tactile, or osmotic stimulus (but not all exposed dentine gives rise to symptoms). It is thought to be due to dentinal fiuid movement stimulating pulpal pain receptors. Prevalence is ~1:7 adults with a peak in young adults, then ↓ with age.2 ∆ is by elimination of other possible causes and by evoking symptoms.

Rx Involves ↓ aetiological factors (i.e. OHI, possibly including tooth- brushing technique and intrinsic and extrinsic dental erosion) and by ↓ permeability of dentinal tubules (e.g. by toothpaste containing strontium &/or fluoride; placement of varnishes, dentine desensitizers, dentine adhesive systems, or, if indicated, a restoration).

Cracked tooth syndrome

Symptoms

Sharp pain on biting—short duration.

Signs

Often relatively few, therefore ∆ difficult. Tooth often has a large restoration. Crack may not be apparent at first but transillumination and possibly removal of the restoration may aid visualization. Positive response to vitality (sensibility) testing and pain can normally be elicited by getting the patient to bite with the affected tooth on a cotton-wool roll or a ‘tooth slooth’. May be associated with bruxing habit.

Rx

An adhesive resin composite restoration may be appropriate in teeth which are minimally restored, but in some cases a cast restoration with full occlusal coverage will be needed. Occasionally RCT may be required.

Periapical/periradicular pain

Progression of irreversible pulpitis ultimately leads to death of the pulp (pulpal necrosis). At this stage the patient may experience relief from pain and thus may not seek attention. If neglected, however, the bacteria and pulpal breakdown products leave the root canal system via the apical foramen or lateral canals and lead to inflammatory changes and possibly pain. Characteristically the patient can precisely identify the affected tooth, as the periodontal ligament, which is well supplied with proprioceptive nerve endings, is inflamed.

Pulpal necrosis with periapical periodontitis

Symptoms

Variable, but patients generally describe a dull ache exacerbated by biting on the tooth.

Signs Usually no response to vitality testing, unless one canal of a multirooted tooth is still vital. The tooth will be TTP. Radiographically the apical PDL may be widened or there may be a periapical radiolucency (granuloma or cyst).

Rx

RCT or extraction.

Acute periapical abscess

Symptoms

Severe pain which will disturb sleep. Tooth is exquisitely tender to touch.

Signs

Affected tooth is usually extruded, mobile, and TTP. May be associated with a localized or diffuse swelling. Vitality (sensibility) testing may be misleading as pus may conduct stimulus to apical tissues. Radiographic changes can range from a widening of the apical PDL space to an obvious radiolucency. It is important to differentiate this condition from a periodontal abscess.

Rx

Drain pus and, if indicated, relieve occlusion. Drainage of pus can often be achieved by entering the pulp chamber with a high-speed diamond bur, steadying tooth with a finger to prevent excessive vibration. After drainage has been achieved it is preferable to prepare the canal and place a temporary dressing. Avoid ‘open drainage’ if possible, but if absolutely necessary for <24h, as after this time further bacterial contamination of the root canal makes subsequent RCT very difficult. If a fluctuant soft tissue swelling is present, this should be incised to achieve drainage. Antibiotics should be prescribed if there is systemic involvement or if the infection is spreading significantly along tissue planes. When the acute symptoms have subsided, RCT must be performed or the tooth extracted.

Chronic periapical abscess

Often symptomless. Possibly associated with persistent sinus. Presentation may be: coincidental finding or acute exacerbation.

Lateral periodontal abscess

Symptoms

Similar to periapical abscess with acute pain and tenderness, and often an associated bad taste.

Signs

Tooth is usually mobile and TTP, with associated localized or diffuse swelling of the adjacent periodontium. A deep periodontal pocket is usually associated, which will exude pus on probing. Radiographs normally show vertical or horizontal bone loss, and vitality (sensibility) testing is usually positive, unless there is an associated endodontic problem (perio-endo lesion).

Rx Achieve drainage of pus. Irrigate with a chlorhexidine solution. If there is systemic involvement or it is a recurrent problem, prescribe antibiotics (metronidazole or amoxicillin). Debride the pocket once acute symptoms have settled.

Non-dental pain

When no signs of dental or periradicular pathology can be detected then non-dental causes must be considered. Other causes of pain that can present as toothache include:

TMPDS (p. 446);
sinusitis (p. 384);
psychological disorders (atypical odontalgia) (p. 426);
tumours (pp. 382 and 480).

Isolation and moisture control

Isolation is required to aid visibility, prevent contamination during moisture-sensitive techniques, maintain a relatively aseptic environment, and protect the patient from caustic materials or aspiration of foreign material.

High-volume suction,

e.g. an aspirator.

Low-volume suction,

e.g. a saliva ejector.

Compressed air

This tends to redistribute the moisture to somewhere else (e.g. your eye) rather than remove it. Should be used with care in deep preparations as prolonged use can cause pulpal damage, let alone displace adhesive materials when the solvent is being evaporated prior to curing.

Absorbents

Cotton-wool rolls. Insert with a rolling action away from the alveolus. Moisten before removal to prevent tearing mucosa.
Paper pads.
Carboxymethylcellulose pads (Dry Tips). Very effective if inserted the correct way round with the impermeable plastic against the tooth.

Rubber dam

This provides effective isolation and also improves access to operating site. It is indicated where moisture control and airway protection are essential, e.g. RCT (RCT without rubber dam is considered negligent), acid-etch technique. With practice, rubber dam can be applied quickly and often saves time in the long run. The dam must be secured to the teeth; several methods are available:

Rubber dam clamps. These consist of two metal jaws linked by one or more bows. Commonly used for posterior teeth.
Floss ligatures.
Wedges.
Proprietary rubber bands (Wedjets®) or pieces of dam, worked through contact points.
By pinching dam between a tight contact point.

Types of dam:

1) Sheet grade, 6-inch square (15cm), which is supported with a frame. Moderate to thicker gauges are preferable.
2) Mask type, which is supported by a paper margin and looped over ears with elastic. Increasingly, latex-free rubber dam is available and arguably should be used routinely.

Placement: Several regimens have been described; the following is popular:

1) Place cotton-wool roll in sulcus beside tooth for treatment.
2) Punch holes, which correspond to tooth size, cleanly in the rubber dam at the centre of each tooth to be included.
3) Try in clamp (with floss tied to it).
4) Fit clamp into appropriate hole, with bridge distally, and using forceps place clamp and dam on to tooth (winged technique). Alternatively, the clamp may be placed first and the dam pulled over (wingless). The latter is especially useful for broken down teeth or poor access.
5) Position dam on other teeth, using floss to ease through contact points.
6) Secure dam anteriorly using one of the methods above.
7) If frame required, position.

8) Put napkin on patient’s chin under dam. A saliva ejector will add to the patient’s comfort.

If using caustic materials, a rubber dam sealer (e.g. OraSeal®) should be used.

Removal:

1) Take away clamps/ligatures, etc.
2) Stretch dam, carefully cut interdental septa with scissors, and remove.

Protection of the airway

Mandatory when fitting crowns, bridges, inlays, and carrying out RCT. Best provided by rubber dam, but if this is not possible a butterfly sponge or gauze can be used.

Gingival retraction

↓ gingival exudate and exposes subgingival preparations prior to impression-taking. Some retraction cords are impregnated with substances such as adrenaline to ↓ bleeding. The cord should be gently placed into the gingival crevice with a cord packing instrument (leaving no tag hanging out) prior to impression-taking and temporization. Braided cords are better than twisted. Bleeding from the gingival margin can be ↓ by applying an astringent. A paste (Expasyl™) which contains aluminium chloride provides for retraction and haemorrhage control. Expasyl™ is useful for preparations finished within or just below the level of the gingival crevice, otherwise retraction cord is more appropriate.

Electrosurgery

May be indicated where a margin extends subgingivally and gingival overgrowth is hampering restoration placement or impression-taking. Also for crown-lengthening procedures, although bone removal is required too.

(See p. 102 on crown lengthening).

Principles of tooth preparation

Why restore?

To restore function.
To prevent further spread of an active lesion which is not amenable to preventive measures.
To preserve pulp vitality.
To restore aesthetics.

However, these reasons need to be evaluated with regard to the patient and the rest of the dentition.

Preparation design

With caries prevalence declining, emphasis has changed from extension for prevention, to minimizing removal of tooth tissue. Tooth preparation should be based on the morphology of the carious lesion and the requirements of the restorative material being used.

General principles of tooth preparation

Gain access to caries.
Remove all caries at ADJ (to prevent spread laterally).
Cut away all significantly unsupported enamel.
There is no need to extend a cavity into self cleansing areas buccally and lingually
Shape preparation so that remaining tooth tissue and restorative material will be able to withstand functional forces.
Shape preparation so that restoration will be retained, i.e. slight undercut for amalgam, none required for resin composite or bonded amalgams.
Check preparation margins are appropriate for the restorative material. Small areas of unsupported enamel may be left if a resin composite restoration is being placed.
Remove remaining caries.
Wash and dry preparation.

Helpful hints

While care must be exercised not to overcut a preparation, do not skimp on access so that caries removal is compromised by poor visibility.
Mark centric stops with articulating paper prior to tooth preparation and try to preserve if possible, or place the preparation margins past the occlusal contact areas.
Avoid crossing marginal ridges.
In removing caries a tactile appreciation of the hardness of dentine is important, therefore use slow-speed instruments or excavators.
The base of the preparation should not be flattened as this runs the risk of pulp exposure.
Unless caries dictates, margins should be supragingival.
All internal line angles should be rounded to ↓ internal stresses.
Removing caries with a large diameter round bur automatically produces the desired shape.
In a proximal box, the margin should extend below the contact point because this is where the caries is!

Amalgam1

(see also p. 608)

Amalgam is brittle, therefore an amalgam cavo-surface margin of at least 70°, preferably 90°, is required to prevent ditching. Also avoid leaving amalgam overlying cavity margins and overcarving.
Accepted minimal dimensions for amalgam are 2mm occlusally and 1mm elsewhere.
In deep preparations, sealers &/or liners are required to seal the dentine and prevent ingress of bacteria.

Resin composite,

p. 610.

Glass ionomer,

p. 618.

Wear precludes their use in load-bearing situations except for 1° teeth, management of root caries, temporary restorations, and the atraumatic restorative technique.

Gold

Relies on minimally divergent walls and cement lute for retention.
A preparation margin of >135° is advisable to give good marginal fit to restoration and to allow burnishing.

It would be foolish to think that experience in tooth preparation can be adequately assimilated from the written text. The purpose of the following pages is to give the reader some practical tips on how to do the procedures considered, as well as to describe recent innovations and techniques.

Nomenclature

Black’s classification of cavities is now not widely used. It has been replaced by the following:

Occlusal (Class I) Cavity in pits and fissures
Proximal (Class II or III) Cavity in proximal surface(s) of any tooth
Incisal (Class IV) Proximal in an anterior tooth, but including incisal edge
Cervical (Class V) Cavity in cervical third of buccal or lingual surface of any tooth.

Occlusal (Class I)

Amalgam

Amalgam is still the most widely used material for occlusal cavities, probably because it is more forgiving of technique than some of the newer materials. It is now widely accepted, however, that resin composite placed in conjunction with minimal preparation techniques has a role in initial lesion management. If enamel margins are cut to an angle of 90° (or, if cusps steeply inclined, >70°) the resultant preparation will be adequately retentive.

Lining

Recently, emphasis has changed, with linings being used to seal the underlying dentine for moderate to deep cavities. Light-cured RMGIs (e.g. Vitrebond™) are now recommended. A preparation sealer (Gluma® Desensitizer) can be used in minimal preparations.

Resin composite

Use of these materials in posterior teeth is increasing as patients request tooth coloured restorations and their concern about amalgam grows. The controversy surrounding posterior resin composites is dealt with on pp. 230 and 612. A technique which has gained more widespread acceptance is:

Preventive resin restoration

Introduced by Simonsen (then by others as the minimal resin composite restoration or sealant restoration!). Preparation is limited to caries removal and the resultant preparation restored using fissure sealant alone if small, or resin composite followed by sealant if larger. Alternatively, GI can be used instead of resin composite. The rationale of this approach is that adjacent fissures are sealed for prevention. It is particularly useful for investigating any suspect areas of a fissure, a technique that is often referred to as an enamel biopsy (obviously coined by an academic). This involves exploring the area with a small bur, and if no caries is found further preparation can be aborted and sealant placed. If carious, a PRR can be carried out. It is often possible to complete preparation of a PRR without LA; however, if the cavity appears larger than originally thought, LA can then be given. If the preparation extends significantly into load-bearing areas, conventional tooth preparation should be carried out and the tooth restored with resin composite or other suitable material.

Technique for medium-sized cavities:

1) Assess whether LA required. If not, ask patient to signal if tooth becomes sensitive.
2) Isolate tooth (preferably with rubber dam).
3) Gain access to caries with a small bur at high speed.
4) Use a small round bur run at slow speed to remove caries. Only remove as much enamel as required for access.
5) Etch preparation margins and occlusal surface. Wash and dry.
6) Apply a dentine adhesive system.
7) Restore preparation with resin composite placed and cured in increments, but don’t overfill.
8) Paint sealant over whole of occlusal surface and cure.
9) Check occlusion.

Where possible a related sealant and resin composite should be used to ensure a good bond.

Hints for resin composite restorations

Use etchant gel in a syringe to aid placement. Many newer adhesive systems do not have a separate etch stage, however, and rely on the use of acidic primers often used in conjunction with bonding resins or as a separate stage, p. 616 in Chapter 14 on dental materials.
Additions are generally easy as new resin composite will bond to old.
Avoid eugenol-containing cements with resin composite restorations.
Resin composite must be cured incrementally, with increments being no deeper than 2mm.

Proximal (Class II)

images Avoid the creation of an overhang at the cervical margin and ensure a good contact point with adjacent tooth with a well-contoured matrix band and wedges.

Amalgam

In practice, preparation size is determined by the size of the carious lesion and extension beyond this should be minimal. Proximal preparations comprise a proximal box with vertical grooves. The preparation should only extend occlusally if there is evidence of caries in the occlusal fissures. Retention from occlusal forces is derived from a 2–5° divergence of the walls towards the floor in both parts of the preparation. Amalgam restorations are prone to # at the isthmus in restorations exte-nded occlusally, therefore sufficient depth must be provided in this area. The width of the isthmus should not be overcut (ideally ¼ to image intercusp width). If the cusps are extensively undermined or missing they should be replaced with a bonded restoration (p. 232). A chisel can be used to plane away unsupported enamel from the margins of the completed preparation to produce a 90° butt joint. In molar teeth with mesial and distal caries it is preferable to try and cut two separate cavities, but often a confluent mesio-occlusal-distal preparation is unavoidable. Increasingly the use of resin composite placed in conjunction with a dentine adhesive system is advocated for the restoration of small to moderate proximal preparations in premolar and molar teeth.

Tunnel preparations

A ‘tunnel’ approach to interproximal caries has been described.1 Access to the caries is made through either the occlusal or buccal surfaces, leaving the marginal ridge intact. This approach is only suitable for small lesions, as when preparation is completed at least 2mm of marginal ridge must remain. The access cavity may need to be widened buccolingually to complete caries removal. Carisolv™ may have a place here to ensure complete caries removal. A piece of mylar strip wedged into place will act as a matrix. A RMGIC is used to fill the bulk of the preparation and the occlusal access cavity restored with a posterior resin composite. In view of the difficulty of accurately removing all the caries, let alone the incidence of marginal fracture, this technique is rarely used.

Resin composite

Posterior resin composites should be used predominately to restore posterior teeth, but the technique is more demanding, taking ~50% longer. In addition, it is difficult to establish adequate contact points and occlusal stops. Polymerization shrinkage can cause cuspal flexure, post-operative pain, and marginal gaps. Direct posterior resin composites are best avoided in the following situations:

Cusp replacements.
Poor moisture control.
Restorations with deep gingival extensions, although a bonded base approach can be adopted.
Bruxism or heavy occlusion.

If a resin composite is to be used then a hybrid material with >75% filler is advisable. Pre-wedging one but not both proximal contacts aids creation of a contact point. Resin composite should be placed, and cured, incrementally. If possible, centric stops should be preserved on sound tooth tissue or the restorative material, but never on the marginal interface of the restoration.1 Use of indirect composite inlays may combat some of these problems (see next section).

Proximal (Class II)—resin composite and inlays

Resin composite and porcelain inlays

These inlay techniques appear to overcome some of the problems associated with direct resin composite restorations. When used in conjunction with an acid-etch technique existing tooth tissue can be reinforced. Curing resin composite outside the mouth with the addition of heat (110° for 5mins) or pressure overcomes polymerization shrinkage and possibly ↑ strength. As the inlays are bonded to the tooth with an adhesive, parallel walls are less important, but undercuts must be removed or blocked out with an RMGI cement (not in the proximal box). In general porcelain inlays offer improved aesthetics, surface finish, and bond in comparison to resin composite inlays; however, placement and adjustment can be more difficult. Ceromers (e.g. belleGlass™) may also be used in similar situations.

Technique: preparation

1) The preparation should have slightly divergent walls, rounded line angles, and a slight bevel of the enamel margins, but not occlusally. For onlays, a minimum 1.5mm reduction of cusps is necessary.
2) Block out any undercuts with RMGIC.
3) Take an impression of the preparation and opposing arch, and if necessary make an inter-occlusal record.
4) Choose shade.
5) Make and place temporary with a proprietary resin-based temporary material (e.g. Fermit, Clip).

Technique: cementation

1) Place rubber dam.
2) Remove temporary and clean tooth.
3) Try-in inlay, and carefully check marginal fit and adjust as necessary. Do not adjust the occlusion at this stage.
4) Polish any adjusted areas.
5) Remove inlay and clean with alcohol. For porcelain only, place layer of silane coupling agent on fitting surface.
6) Etch enamel and dentine (total etch concept). Wash and remove excess moisture, but do not dry.
7) Place dentine-adhesive system to moist surface.
8) Apply dual-cure resin composite luting cement to prep and inlay and carefully seat.
9) Cure for 10sec and then remove any excess resin composite.
10) Complete light-curing (dual-cure resin composite will finish setting chemically under inlay in ~6min).
11) Trim any excess cement (especially interdentally) and polish.
12) Check occlusion and adjust.

Proximal (Class III), incisal (Class IV), cervical (Class V), and root surface caries

Anterior proximal

Resin composite is the most widely used material for anterior proximal restorations.

Access should be gained from either the buccal or lingual aspect, depending on the position of the lesion. As resin composite is adhesive the preparation is just extended sufficiently to remove all peripheral caries. Some unsupported enamel can be retained labially, but the margins should be planed with chisels to remove any grossly weakened tooth structure. Tooth preparation can be almost entirely completed with slow-speed burs and hand instruments. Ideally the margins are bevelled. A slight excess of material should be moulded into the preparation with a mylar strip, wedged cervically. Once the material is set, the excess can be removed. After checking the occlusion the restoration can be polished using one of the proprietary products (e.g. Sof-Lex™ discs, Enhance®) if necessary.

Incisal

The restoration of choice is resin composite, the so-called ‘acid-etch tip’ (p. 100); however, for large incisal cavities in the adult patient, a dentine-bonded crown or porcelain veneer may give better retention and aesthetics.

Cervical

Although cervical cavities are seen less frequently in younger patients, they are an ↑ problem in older age-groups with gingival recession. Resin composite e.g. flowable, compomer, or RMGIC are the preferred materials in this situation. Amalgam should be avoided in this situation due to the possibility of a lichenoid reaction.

Once caries has been removed the occlusal margin should be bevelled. The cervical margin should not be bevelled as it has been shown to ↑ microleakage. The materials are ideally placed incrementally under rubber dam isolation.

Root surface caries

As gingival recession is a prerequisite to root caries, it occurs predominantly in the >40-yr age group. Dentine, which has a critical pH below that of enamel, is thus directly exposed to carious attack. It is sometimes seen secondary to ↓ saliva flow (which reduces buffering capacity and may alter dietary habits) caused by salivary gland disease, drugs, or radiation. Long-term sugar-based medication may also be a factor. Rx requires, first, control of the aetiological factor, and for most patients this involves dietary advice and OHI. Topical fluoride varnishes, high fluoride toothpastes and mouthrinses may aid remineralization and prevent new lesions developing. However, active lesions require restoration, typically with a traditional or RMGIC. See also severe early childhood caries p. 90.

Management of the deep carious lesion

Assessment

Is the tooth restorable and is restoration preferable to extraction?
Is the tooth symptomless? If not what is the character and duration of the pain?
Test vitality and percuss the tooth (before LA!).
Take radiographs to check extent of lesion and if apical pathology.

Management Depends upon a guesstimate of pulpal condition (p. 220).

Irreversible pulpitis/necrotic pulp—Rx: RCT (p. 276) or extraction. Reversible pulpitis/healthy pulp—aim to maintain pulp vitality by selective removal of carious dentine without pulp exposure. If in doubt Rx as reversible pulpitis. Can always institute RCT later.

There is some evidence that in symptomless teeth with deep carious lesions partial, rather than complete, removal of caries is preferable as it reduces the risk of pulp exposure. It is not known yet whether it is necessary to re-enter and complete excavation at a later date (stepwise excavation of caries)1

Rationale

Bacteria sealed under a restoration that provides a good peripheral seal are denied substrate, therefore lesion arrests. This allows the pulpodentinal complex to lay down reparative dentine.

Exposure

If traumatic, small, and uncontaminated, perform direct pulp cap with hard-setting calcium hydroxide or MTA (mineral trioxide aggregate) and restore.
If carious exposure, and continued pulp vitality is doubtful, RCT will be required. If time short, can dress tooth with Ledermix and a traditional GI cement, and extirpate pulp at next visit.

Pulpotomy Is removal of coronal part of pulp in order to eliminate damaged or contaminated tissue. It is indicated for teeth with immature apices, as continued vitality of apical pulp will allow root formation to proceed. Once the apex has closed, conventional RCT can be carried out. The pulp is amputated to the cervical constriction, dressed with non-setting or hard-setting calcium hydroxide or MTA and the tooth temporarily restored.

Materials used in the management of pulp vitality

Calcium hydroxide

has a pH of 11, which makes it bacteriostatic and promotes the formation of a calcific barrier. When calcium hydroxide comes into contact with the pulp a zone of pulpal necrosis is formed. This is subsequently mineralized with calcium ions from the pulp. It is the material of choice for direct pulp caps, particularly the hard-setting type.

Mineral trioxide aggregate is

a very slow setting material. Similar in nature to industrial cement. Very biocompatible.

Ledermix

is a mixture of triamcinolone acetonide (a steroid) and demethyl chlortetracycline in a water-soluble base. It has anti-inflammatory and bacteriostatic properties, but also suppresses pulpal defences, therefore resulting in the rapid spread of any bacteria not affected by the antibiotic it contains. It is a useful compromise for the management of irreversibly inflamed pulps where anaesthesia may be a problem, or when pulp extirpation has to be delayed.

Survival and failure of restorations

Survival of restorations

The results of Elderton’s study into the durability of routine restorations placed in the General Dental Services in Scotland provided both a shock and a stimulus to the profession, as he found that 50% lasted for less than 5yrs.1 This led to debate over both clinical technique and the profession’s readiness to replace restorations. It has been reported that 60% of practitioners’ time is spent replacing restorations. It is also interesting to note that those patients who change dentists frequently are more at risk of replacement restorations than those who are loyal to the same GDP.2 In order to ↑ longevity we need to consider the reasons for the failure of restorations and ∆ of secondary caries.

Reasons for failure of restorations

Incorrect ∆ and treatment planning; e.g. pulpal pathology; caries of another surface; extraction of tooth for another reason.
Poor understanding of the occlusion.
Incorrect preparation; e.g. caries left at ADJ; incorrect margin preparation; inadequate retention; preparation too shallow; weakened tooth tissue left unprotected.
Incorrect choice of restorative material; e.g. inadequate strength or resistance to wear for situation.
Incorrect manipulation of material, e.g. inadequate moisture control; over- or under-contouring.

Before replacing a failed restoration it is important to identify the cause of failure and decide whether this can be dealt with by replacement or repair. When making this decision bear in mind that cavity size is ↑ on average by 0.6mm each time a restoration is removed.3

Secondary caries

Unfortunately, placement of a restoration does not confer caries immunity upon a tooth. When caries occurs adjacent to a restoration it is called secondary or recurrent caries. More correctly it is defined as a new lesion which just happens to be adjacent to an existing restoration, and it should be managed in its own right. While secondary caries is an accepted phenomenon, we as a profession have perhaps been a little too ready in the past to diagnose and treat it. Ditched amalgam margins are not a reason for replacement per se, and active intervention is only required if caries can definitely be demonstrated as active. Secondary caries is difficult to diagnose, but careful observation (clinically and radiographically) rather than intervention, is now advocated. Intervention is only indicated when the lesion is in dentine, and there is evidence of progression &/or cavitation is present.

To prevent secondary caries it is important not only to educate the patient to reduce their caries rate, but also to examine our restorative technique, to ensure good long term-restorations.

Occlusion—1

In a book of this size it is (thankfully) not possible to consider all aspects of occlusion; therefore we will try to concentrate on the practical aspects and leave the more esoteric considerations to other texts. We also suggest that significant occlusal adjustment is rarely indicated and should only be attempted by a specialist.

Definitions

Ideal occlusion

Anatomically perfect occlusion—rare.

Functional occlusion

An occlusion that is free of interferences to smooth gliding movements of the mandible, with absence of pathology.

Balanced occlusion

Balancing contacts in all excursions of the mandible to provide therefore ↑ stability of F/F dentures; not applicable to natural dentition (except rarely in full-mouth reconstruction).

Group function

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Jan 5, 2015 | Posted by in General Dentistry | Comments Off on 6 Restorative dentistry
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