Minimally-invasive non-surgical periodontal therapy

The case for non-surgical disease management

That non-surgical treatment is an effective method for treating chronic periodontitis (or indeed the less common aggressive form of disease) is not in doubt; a systematic review and meta-analysis published in 20055 reviewed the findings of three previous systematic reviews, published between 1993 and 2002, confirming that better treatment outcomes can be achieved by non-surgical means, when compared to surgical treatment, for moderate pockets (up to 6mm), while surgical treatment is only of greater benefit for deeper pockets in excess of 6mm. Although this appeared to show that deep pockets should be treated surgically, the authors pointed out that this latter finding is only applicable to 12-month post-treatment results and those studies that followed patients for 5 years or more found that, even for deep pockets, non-surgical therapy was as effective as surgical treatment.

However, fundamental to the successful management of disease by non-surgical means (or indeed surgical means for that matter) is the establishment, before any treatment is carried out, of optimal self-performed biofilm control.

The patient's role in disease control

Although the evidence base for an association between personal oral hygiene and the control or prevention of chronic periodontitis is surprisingly weak (there are no randomized controlled trials to show such an association for instance),6 it is assumed that an adequate level of daily plaque control is a pre-requisite for successful periodontal therapy of any form. For example, the Sixth European Workshop in Periodontology in 20087 stated that: “It should be noted that the performance of optimal oral hygiene practices is an inseparable principle to be observed with any protocol of mechanical debridement”. The effects of good biofilm control before starting treatment can be dramatic (Figure 1), the goal being to establish an optimal supragingival environment prior to starting subgingival instrumentation. The reduction in marginal inflammation that results from a high standard of biofilm control has a number of benefits for both patients and clinicians: in the absence of inflammation, treatment can be more comfortable for patients and for operators it can be easier to carry out. Most importantly, however, during this oral hygiene phase (Figure 2), it is preferable not to carry out any form of instrumentation – the patients then learn that, through their own efforts, they can have a profound effect on the condition of their gums and thus ‘self efficacy’ is enhanced. The presence of supragingival calculus is not necessarily a barrier to the establishment of optimal plaque control, which suggests that calculus does not in itself cause inflammation.8

Patients' efforts are not restricted to the supragingival region and, as well as marginal and interdental plague control methods, patients should be shown how to clean subgingivally (Figure 3). In this way, patients can disrupt the accessible biofilm below the gingival margin, which leaves disruption of the less accessible biofilm one of the objectives of treatment (Figure 4). Traditionally, the other principle therapeutic objectives have included the removal of all subgingival calculus and any contaminated root cementum.

Therapeutic objectives – changing approaches

While it is widely accepted that mechanical biofilm removal is the cornerstone of successful periodontal therapy,9^,10 much emphasis in the past has been placed on the removal of all subgingival calculus deposits, and also on the removal of contaminated cementum by root planing with sharp hand instruments, a technique that was described in the dental literature in 19131 and which was illustrated in Egyptian hieroglyphics 4000 years ago.

The association of subgingival calculus with periodontal lesions has led to the assumption in the past that there is a cause and effect relationship between these two phenomena; a review of the evidence,8 however, has shown that calculus is the result of disease and not its cause and that periodontal healing occurs in the presence of calculus as long as the overlying bacterial biofilm is removed. Calculus is thus an inert material and its formation could perhaps be regarded as a protective mechanism, since it represents the calcification of potentially pathogenic biofilm. Therefore, clinically, it can be observed that, in the presence of optimal biofilm control by the patient, but in the absence of subgingival calculus removal (for example during the oral hygiene phase of treatment), healing of the periodontal lesion can take place and gingival shrinkage exposes previously subgingival calculus (Figure 5). The removal of calculus then becomes necessary for better access to the subgingival biofilm and for aesthetics. In the past, too much emphasis has been placed on complete calculus removal for disease control, both in training and practice, but such emphasis is misplaced and the focus should instead be on biofilm disruption by both patients and operators. In other words, plaque removal is more important than calculus removal.11 In reality, it is as well that complete calculus removal is less important than was previously thought because many studies have shown that complete calculus removal is rarely, if ever, achieved.12^,13^,14^,15 One review16 showed that, even after 12–15 minutes of treatment per tooth, 63% of root surfaces still harboured residual calculus.

What then of the role of contaminated cementum in periodontal disease? Stillman, in 1917,17 described the need for planing of the root (or ‘skinning’ as it was sometimes called then) with instruments with “keen cutting edges… leaving this surface as clean as a billiard ball, and equally as well polished”, the goal being to remove the cementum layer which had been shown to be closely associated with bacteria and their toxins,18^,19^,20^,21 or even, it was suggested, ‘deeply penetrated’ by bacterial endotoxin.22 This concept persisted for much of the 20th Century and the process of scaling and root planing (SRP), quadrant by quadrant under local anaesthetic, became the norm in non-surgical disease management, requiring considerable time and technical skill, the use of highly sharpened (and therefore damaging) hand instruments and significant post-operative discomfort for the patient. But, in the early 1980s, doubts started to be raised about the location of bacterial toxins on the root surface and the need for such invasive treatment, which could result in significant iatrogenic tooth surface loss (Figure 6). A number of studies at this time suggested that bacterial toxins were only loosely adherent to the root surface and could be removed by much lighter instrumentation which did not damage the root surface to the same extent.3^,4^,23^,24^,25^,26 One in vitro study24 showed that over 99% of the bacterial contaminants could be removed by light instrumentation alone, without the need for cementum removal by root planing. This led to the concept of root surface debridement (RSD)27^,28 as an alternative to root planing, the goal being the achievement of a biocompatible root surface without the removal of tooth structure. Thus it was shown that RSD had the potential to achieve the same level of root surface decontamination as root planing but with the advantages of conservation of tooth structure, shorter treatment time and greater patient comfort. In addition, the concept of RSD allowed for the exclusive use of ultrasonic instrumentation, since there was no need to remove cementum by hand planing. Furthermore, ultrasonic use has been shown to be as effective as hand instrumentation in terms of clinical and microbiological treatment outcomes29^,30^,31 and is much less technically demanding. The use of local anaesthesia is often unnecessary with such light instrumentation, thus reducing the potential for iatrogenic damage and this, combined with the shorter treatment time, also permits a full-mouth treatment approach, as opposed to quadrant by quadrant treatment, which has been shown to yield better treatment outcomes.32^,33^,34^,35^,36 The term ‘full-mouth ultrasonic debridement’ (FMUD) has been used to describe this type of non-surgical therapy35 in which full-mouth treatment is carried out using ultrasonic instrumentation exclusively and with a debridement technique rather than a planing approach. Over time, and with consistent patient adherence, stable results can be readily achieved (Figure 7), often with spontaneous healing of vertical bone defects (Figure 8). Several studies have directly compared the minimally invasive FMUD approach, comprising a single visit of less than one hour, with the traditional SRP approach of 3–4 hours of root planing, by quadrant with local anaesthesia, over four visits.37^,38^,39 In each case, the treatment outcomes were identical, leading one author39 to state that: “periodontal debridement…may be assumed as a viable approach to deal with severe chronic periodontitis”. This has led the Sixth European Workshop (2008) to recognize that there is a need to investigate the impact of different mechanical debridement protocols on patient-centred outcomes and cost-effectiveness.7

Clarity or confusion?

The difference between root planing (RP) and RSD would seem to be clear; RP has been defined as: “…a technique of instrumentation by which the ‘softened cementum’ is removed and the root surface is made ‘hard’ and ‘smooth’…” and RSD as “… removal of plaque and/or calculus from the root surface without the intentional removal of tooth structure”.2 The difference has recently been further clarified by the inclusion of the term ‘Periodontal Debridement’ in the National Library of Medicine's Medical Subject Headings (MeSH) database where it is defined as: “Removal or disruption of dental deposits…without deliberate removal of cementum as done in root planing and often in dental scaling”. Despite this apparent clarity in terminology and treatment objective, the term RSD is often used synonymously, and erroneously, with RP40^,41 and hand instruments (planing instruments) are often used, and taught to be used, as debridement instruments. This is analogous to using a highly sharpened sharp wood plane to clean a wood surface without removing any of the wood itself. Partly this confusion arises from a resistance, in some quarters, to the idea of achieving periodontal health by minimally-invasive approaches. There may be a number of reasons for this; traditional SRP is effective so there is a reluctance to change position, which is always unsettling. In addition, SRP has been in use for so long that educational programmes (especially in hygienist training) and practices have evolved on the back of these concepts and industry has responded by manufacturing and selling the tools needed to treat patients in these ways.

Future developments

There is a growing evidence base that it is disruption of the biofilm, both by patient and clinician, rather than calculus or cementum removal, that is the key to controlling periodontal diseases.9^,42 The patient's role in this process is clearly crucial. Professional interventions that concentrate on biofilm disruption, with minimal effects on tooth structure, are being investigated in the form of laser instrumentation,43 the use of photodynamic disinfection44 and air polishing devices,45 and hold out the prospect of achieving periodontal stabilization with minimal harm to the patient and more cost-effectively than traditional methods.