by Clayton A. Chan, D.D.S.
This short posting appear as a 4th part to an original posting made on the former genR8TNext internet forum under the subject: Re: [CROWNS] TMD/Wear, No Anterior Guidance on Monday, September 04, 2000 9:44 AM.
Rather than continue to concentrate on stronger materials, better bond strengths, stronger better reinforced materials, which are better than ever before, the treating clinician should seriously consider the physiology of muscles and their impact it has on mandibular position which effects occlusal and incisal position. The mandible with comfortable rested muscles that function in a normal unstrained manner are not destructive to there supporting dentition. Breakage, incisal wear, porcelain and composite fracturing, etc., are a result of a pathological phenomenon which directly leads to possible lack of a proper mandibular positioning, lack of proper vertical dimension, lack of an optimal AP position, increased muscle hypertonicity and activity, resulting in further parafunctional habits of bruxism.
There should be harmony in the masticatory muscles, teeth and the jaw joints. Whenever these three anatomical factors are not harmonized one with another further wear and tear are exerted to the stomatognathic system resulting in breakdown and clinical frustration.
BACK TO THE BASICS
From my personal experience, I have observed that most anterior incisal wear cases are typically overclosed vertically with mandibles posteriorly positioned. Many of us clinicians have been scared to believe that opening the bites is detrimental to the patient. We have also been informed to believe that bringing the condyles down and forward are questionable. In my opinion, there has been more detriment to dentition by not having enough vertical support of the occlusal table, which has been well documented and observed by us dentists that we cannot deny. Those cases that present with insufficient vertical typically also too often have compromised swallowing patterns that have been confirmed by many kineseographic studies. A lack of proper posterior molar and bicuspid occlusal support vertically will naturally result in an accentuated anterior overlapping of incisal edges. With this overlapping of incisal edges and contouring, which we aesthetic conscientious clinicians strive to develop, bringing length back to the worn dentition, we then naturally risk these works of art to be placed in harms way by pathologic mandibular movements both protrusively and excursively, when these incisal edges are not within the confines of the functioning movements of muscle physiology.
Why work against nature? Each patient’s case is unique. For all the more reason we should seriously consider the following. Develop a proper maxillo-mandibular physiologic position vertically and AP wise to prevent anterior breakage and establish rested masticatory musculature. Establish proper tongue space for proper swallowing patterns to occur rather than the tongue posturing between the teeth when swallowing (natures compromised splint, indicative of a deficient vertical or too much freeway space). When swallowing, teeth should brace against themselves. Establish a physiologically positioned mandible in the anterior-posterior position, especially if doing full mouth rehabilitation, thus avoiding the need for long centric. Establish a proper arch width horizontally, giving additional room for tongue swallowing patterns as well as facial aesthetics in the smile (fuller smile) with buccal corridors fuller. Airway breathing constrictive concerns will be minimized by developing the dental arches horizontally impacting the upper turbinates with those patients with high vaulted palates (less mouth breathing problems and aberrant tongue swallowing patterns). Resulting in a more stable occlusion, improved aesthetics, enhanced facial features, calmer comfortable muscles of the face, head and neck regions.
Happy muscles, happy teeth, happy patients and happy dentists!