now for a little ramble on everybody's favourite dental hard tissue lesion, the non-carious cervical lesion!
scourge of all honest dentists, NCCLs of varying shapes and sizes can be found in just about every mouth. NCCLs as a lesion also have various aetiologies and thus serve as diagnostic indicators for complex problems in the mouth. a lesion is after all part of a complete disease process...
the NCCL can be generated by factitious means (overbrushing) as well as from occlusal overloading (bruxism), while their appearance can be modified by acid erosion. the key is to be able to identify each possible cause, and to link them up into a total treatment plan.
the NCCL of overbrushing is by far the most common type of NCCL. sheer chronic traumatic brushing force will over time cause gingival recession. the denuded root surface is then worn away by the same chronic brushing force, creating smooth-surfaced depressions in the root dentine. enamel may also be lost due to an undermining effect, but will have a smooth surface.
the NCCL of bruxism is a rarer lesion. current theories point to loss of the enamel and later dentine at the CEJ region due to flexion of the tooth under parafunctional loads. the lesion will have a well-defined wedge shape, and the coronal margin at the enamel will have a sharp edge. this lesion, seen early enough, will actually be bounded by enamel, unlike the overbrushing NCCL which begins in dentine. later lesions will, due to increase in size in an apical direction, have their gingival margins in dentine, but will once again have the classic sharp edge to the enamel border.
Acid erosion modifies the shape of the NCCL by eating away at its borders. the coronal edge is more affected, possibly due to the higher mineral content of the enamel. the effect is a dramatically wide lesion with reference to its coronal-apical dimensions, with an enamel involvement often 3mm or more in height. the surface is smooth and gives the restorative dentist headaches in trying to figure out how to place a bevel for his composite.
in the whole scheme of things, aetiology will lead to diagnosis, diagnosis will lead to treatment planning, and then on into review and a re-planning if necessary. it goes without saying that all 3 conditions identified should be dealt with.
overbrushing can be dealt with, first by education and then by devising a monitoring system. education for me would consist of actually getting the patient to stick out his hand so you can demonstrate on his skin/thumbnail what adequate brushing pressure truly means. once the patient has been told about soft toothbrushes, he is also informed that he can self-monitor; he will still be overbrushing if his toothbrushes spoil rapidly or his new restorations have been rubbed away by his brushing. this also incentivises the patient by empowering him to take care of his own condition.
bruxism is of course a much more tricky proposition to deal with. splints and such are by no means simple things to manage, and given the complex, multifactorical nature of the bruxism syndrome, referral is always a viable option.
acid erosion will require a careful review of dietary intake. acid erosion from dietary sources tends to lead to NCCL aggravation, whereas acid reflux from GERD or bulimia will lead to erosion of the palatal surfaces of the teeth, especially the upper anteriors and first premolars, and the 2 problems could of course also come superimposed. it is also a given that what the dentist considers acidic and detrimental to dental health a patient may consider a normal part of his diet, for example an orange every day as an afternoon snack or grapefruit juice with the breakfast. modifying of behaviour as opposed to banning may be more effective in the long run, as a patient may be more willing to listen if you tell him to rinse with water and apply Recaldent as opposed to being faced with a bleak future containing no lime juice after his lunches.
once the aetiologic cause has been at least initially addressed, the dentist can consider the question of restoration. i personally take a conservative approach to restoring the NCCL. if the lesion's cause has been dealt with, they will of course not get deeper, and restoration becomes option if the lesion does not trouble the patient aesthetically or via sensitivity.
most of us have been at least cursorily trained to deal with NCCL lesions using direct restorative materials, including the whole tooth-coloured restorative spectrum of composite resins and glass ionomer resins. other options, although now out of vogue, include amalgam and direct gold. a further consideration of an indirect restoration, for example CAD-CAM ceramics or even an indirect composite resin, were mooted over dinner with some friends but i have yet to try these or even heard of these being issued to a patient as of yet.
direct restoration of the NCCL faces a few challenges. the first is crevicular fluid, possibly compounded by blood in the case of the gingivitis patient. the second is aesthetic considerations with colour and contour, having to match the colour of both the coronal enamel as well as the root dentine. the last are the mechanical and chemical challenges faced by the restoration with respect to the aetiologic factors which created the NCCL in the first place.
crevicular fluid, flowing freely from the sulcus of an inflamed patient, is the bane of the restorative dentist. either the material must be able to handle the presence of fluid and its challenges to the material as well as its bond to tooth structure, or the dentist must be able to practically, if not absolutely, eliminate the crevicular fluid. for the first option, glass ionomer is the usual favourite option. while the material handles crevicular fluid a whole lot better than its other tooth-coloured alternatives, bathing it in crevicular ooze or blood is an invitation to failure. it may in fact be best to scale the patient, institute OHI and chemical adjunctives such as antibacterial mouthwash, and return to the problem in a few weeks when the gingiva is more willing to behave. this is cold comfort for the dentist faced with impatient patients or long intra-visit times which he can do nothing about. a second option mentioned by a colleague was an on-the-spot laser gingivectomy; laser ablation of inflamed and overhanging tissue, with its attendant cauterisation, would help greatly in terms of relative isolation of the lesion.
how does one choose shade for an NCCL? match to the coronal enamel, match to the root dentine, choose a happy medium, do a 2-colour build-up? there is no safe answer for this, as every aesthetic situation varies. this will become a major pitfall if root dentine colour varies greatly from coronal enamel colour, especially if there is exposed root on adjacent teeth which is not to be restored. long bevels on the coronal enamel are a great help when trying to achieve a colour match in an unfavourable situation, or if the edge of the NCCL has been back-stained by dietary content, when using a composite resin; the opacity of glass ionomer generally provides much more colour masking at the risk of an opaque and obvious restoration if colour match is sub-optimal. contour is also critical; a flat restoration is un-natural and may trap food. over-contoured restorations, on the other hand, will stick out and look 'pregnant' and unaesthetic. adequate contour helps to hide the restoration as well as provide a more 'self-cleansing' shape that will aid hygiene. good fine diamonds are critical for this.
finally, not every material is suitable to every NCCL. glass ionomer beats composite resin flat in terms of flex resistance, which will be critical in the stress-fracture NCCL of the bruxer. conversely, in acid environment or when faced with mechanical trauma from overbrushing, composite resins will perform better. when conditions with varying requirements coexist ot create an NCCL of multifactorial aetiology, simplify your problem by eliminating one cause first and restoring in a manner to suit the more intractable problem.
once the NCCLs have been restored, the dentist must be able to evaluate success. the restoration now becomes a diagnostic indicator of the success in eliminating aetiology. if, despite your best efforts in restoring, you notice the restorations disappearing in months, obviously something is wrong. perhaps your overbrusher has not taken your OHI to heart. perhaps your bruxer hates his splint. perhaps your dietary acid patient has fallen back on his usual comfort food without the hygiene behaviour modifications that you prescribed for him. in such a situation, reevaluate the causes, your aetiological control measures, and then re-restore the patient so that your monitoring devices are back in place!
