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References

Lussi A, Gygax M. Iatrogenic damage to adjacent teeth during classical approximal box preparation. J Dent. 1998; 26:435-441
Moopnar M, Faulkner KD. Accidental damage to teeth adjacent to crown-prepared abutment teeth. Aust Dent J. 1991; 36:136-140
Milic T, George R, Walsh LJ. Evaluation and prevention of enamel surface damage during dental restorative procedures. Aust Dent J. 2015; 60:301-308
Wilson NHF.New Malden: Quintessence Publishing Co Ltd; 2007
Qvist V, Johannessen L, Bruun M. Progression of approximal caries in relation to iatrogenic preparation damage. J Dent Res. 1992; 71:1370-1373

Iatrogenesis and how to prevent it

From Volume 44, Issue 5, May 2017 | Pages 464-465

Authors

Louis Mackenzie

BDS, FDS RCPS FCGDent, Head Dental Officer, Denplan UK, Andover

General Dental Practitioner, Birmingham; Clinical Lecturer, University of Birmingham School of Dentistry, Birmingham, UK.

Articles by Louis Mackenzie

Article

Every day millions of operative dental procedures are carried out by clinicians worldwide. The majority of these involve the replacement of existing restorations prior to tooth preparation for new direct or indirect restorations. Unfortunately, when anterior and posterior tooth preparations involve proximal surfaces there is a high risk of accidental damage to previously healthy adjacent structures which may have negative consequences for oral health in the short- or long-term.

In many parts of the world, minimally invasive (MI) techniques are now at the forefront of contemporary restorative dentistry and the prevention of iatrogenic damage to hard and soft tissues is one of the fundamental MI principles.

Prevalence

It is well documented that the prevalence of iatrogenic damage is extremely high. Tooth preparation of Class II cavities almost always results in some level of unnecessary damage to adjacent hard tissues1 and indirect preparations carry a 75% risk of iatrogenic damage to one or both adjacent teeth.2

A recent study demonstrated that, when using high-speed rotary instruments, experienced dentists damage 75% of adjacent surfaces with a range of severity, rising to 95% for inexperienced dentists, with extensive damage recorded in over 20% of cases.3

Aetiology

Iatrogenic damage has been described as being ‘virtually impossible’ to avoid owing to the environment in which operative procedures are carried out.4 The main aetiological factors predisposing to iatrogenic damage are:

  • Technique sensitivity of operative procedures;
  • Close proximity of adjacent structures;
  • Limited visual access, eg distal surfaces of posterior teeth;
  • Field of vision obscured by coolant, blood or saliva;
  • Awkward cavity outline forms;
  • Use of instruments rotating at up to 400,000 rpm;
  • Small patient head movements.

    • Consequences

    Iatrogenic damage often results in negative consequences, eg even slight bur contact with adjacent enamel damages the outer acid-resistant aprismatic layer, exposing deeper layers that are more susceptible to demineralization. Some of the complications that may result from iatrogenic damage are:

  • Significant increase in restoration rate;5
  • Increased caries risk;5
  • Increased risk of periodontitis;
  • Surface roughness increases plaque retention and complicates its removal;
  • Flattened or concave surfaces complicate contact point restoration;
  • Increased risk of future radiographic mis-diagnosis;
  • Increased risk of post-operative sensitivity to thermal stimuli.

    • A clinical example is presented in Figure 1.

    Figure 1. Carious lesion affecting an iatrogenically damaged tooth surface.

    Repair of iatrogenic damage

    Hard tissue defects are irreversible and may be challenging to repair due to limited access for vision and instruments and difficulties in moisture control and adaptation of thin layers of restorative material. While slight periodontal trauma may be expected to repair naturally, damage to the connective tissue attachment (biological width violation) routinely results in persistent inflammation.

    Prevention of iatrogenic damage

    A number of techniques are available to reduce the risk of iatrogenic damage and, if optimized, have the potential to eliminate it completely.

    Protective wedges

    While restorative matrices may be used to protect teeth, they are very thin and can impede visual access. Innovative protective wedges (Figure 2), inserted before the risk of iatrogenesis arises, are effective in protecting adjacent tissues during all stages of cavity preparation and confer the following additional advantages:

    Figure 2. Protective wedges (Directa Dental Ab, Upplands Väsby, Sweden). (a) FenderPrep™ (Silver) for use during indirect preparations; (b) FenderWedge™ (Yellow) – available in 4 sizes; (c) FenderPrime™ (Green) (2 lengths) for protection and restoration of deciduous teeth.
  • Compression/protection of interdental papillae;
  • Improved visual access;
  • Enhanced moisture control and haemostasis;
  • Tooth separation which enhances tight restorative contact formation.

    • Optimizing visual access

    Visual access may be improved by a selection of optical aids which are available in a range of standardized magnifications and recent adjustable versions (Figure 3).

    Figure 3. Eyezoom™ adjustable loupes (Magnification 3X, 4X and 5X) (Orascoptic, Middleton, Wisconsin, USA).

    Loupes with approximately 2.5X magnification may be considered optimal for routine operative procedures with magnifications increasing beyond 20X for operating microscopes. Powerful, integrated, LED lights may also be used to provide outstanding illumination of the operative field.

    Further visual enhancement may be achieved by employing techniques that control moisture and retract soft tissues, including:

  • Patient/operator positioning and soft tissue retraction to enable direct vision;
  • Use of front surface reflecting mirrors;
  • Expert use of high volume aspirators and saliva ejectors;
  • Rubber dam isolation;
  • Use of retraction cord;
  • Use of astringent materials to control haemorrhage and gingival crevicular fluid production.

    • Tooth preparation equipment and techniques

    Careful clinical technique is of prime importance in avoiding iatrogenesis. The risk should be assessed pre-operatively and sufficient time allocated to the most difficult aspects of operative procedures. Other safe-preparation techniques that may be used in combination are:

  • Conservative access to Class II lesions through marginal ridges, preserving a thin strip of protective proximal enamel;
  • Use of hand instruments to fracture weak residual proximal enamel;
  • Preservation of slivers of mesial and distal enamel to protect adjacent teeth during indirect preparations;
  • Use of enamel hatchets and cervical margin trimmers for controlled marginal finishing;
  • Use of hand excavators and slowly rotating round burs for improved tactile feedback during caries excavation;
  • Use of end-cutting burs to prepare the cervical margins of proximal boxes (Figure 4) and to enable safer finishing of indirect preparation margins;
  • Use of thin diamond or tungsten carbide finishing burs;
  • Use of slow and/or torque control handpieces for enhanced bur control;
  • Use of safe specialized safe-sided sonic preparation tips.
    • Figure 4. End-cutting diamond bur (DIATECH, Coltène, Altstätten, Switzerland).

    Summary

    Iatrogenic damage is an exceptionally common complication of operative procedures and may result in a range of negative effects. A variety of methods are available for minimizing accidental injuries and, if carefully employed, may eliminate the risk completely.