The Shortened Dental

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Prosthodontics

Smile Magazine20

The loss of teeth is still traditionally seen as an inevitable part of the ageing process. In this context oral

rehabilitation has the capacity to satisfactorily restore function by the replacement of all lost teeth

according to anatomical norms. However, recent clinical studies have found that oral and systemic

health and indeed quality of life or patient’s satisfaction do not specifically depend on the presence

of a full complement of teeth (Elias & Sheiham, 1998). It has been observed that a large proportion of

middle-aged and elderly patients are satisfied with their oral function even after molar loss and that

the retention of solely the anterior and premolar teeth may be sufficient to satisfy the aesthetic and

functional requirements of the majority of elderly patients.

Clearly the loss of a large number of teeth or ill fitting or inadequate dentures can have some degree of

impact on quality of life, but limitation in chewing may not always be as readily apparent to the patient

(Agerberg, 1988). The ‘shortened dental arch’ (SDA) represents a frontier between what is healthy/

comfortable and pathological/uncomfortable for most middle-aged anda elderly people (Figure 1).

Active patient involvement in clinical decision-making in conjunction with the use of accurate scientific

information is one of the fundamental tenets of evidence-based health care (Adams & Drake, 2006),

and therefore a patient’s opinion should be taken into account and combined with other factors i.e.preservation of oral tissues, systemic status and cost. The maintenance of a SDA may prove advanta-

geous in terms of preservation and costs when compared with dental prostheses because it does not

necessitate the preparation of abutment teeth, surgery or the fabrication of dentures. It is conceivable

that alteration in the efficiency or any impairment of chewing may hinder digestion which in turn may

have a compounding effect on general health. However, chewing impairment may only have a limited

effect particularly as modern diets are based on foods with a soft consistency. Even foods which are

less readily digestible require less than 30% of the masticatory performance of a completely dentate

subject (Farrell, 1956). Providing that partial edentulism does not influence food selection it should not

be considered a significant cause for systemic health problems (N’gom & Woda, 2002).

Although this concept arose in developed countries, it is equally valid for populations in developing

countries i.e. diets and cultures are variable. A study carried out in Tanzania of 725 participants with

different permutations of the SDA compared 125 participants with complete natural dentition (Sarita

et al., 2003). It was found that although some loss of function occurred after the loss of molars the

(Figure 1)Possible settings for a

SDA (adapted from

Witter et al., 1997).

“OU”- occlusal units.

Zbys Fedorowicz

Vinícius Pedrazzi

Raphael Freitas de Souza‘

The Shortened Dental Arch:

An Evidence-Based Treatment Option

DDS, PhD (Oral Rehabilitation)

Profess• or, Ribeirão Preto DentalSchool – University of São Paulo Author, the Cochrane Oral Health•

[email protected] •

MSc, DPH, BDS. LDS RCS (Eng)

Director • of the Bahrain Branchof the UK Cochrane Centre Author, the Cochrane Oral•

Health Group

[email protected].• bh

DDS, PhD (Oral Rehabilitation)

Associ• ate Professor, RibeirãoPreto Dental School – University of São [email protected] •



Smile Magazinewww.smile-mag.com 21

forms to the following principles (Ash & Ramfjord,

1995):

Absence of pathological processes;1.

Satisfactory function – mastication, swallowing2.

and speech;

Variations of form and function;3.

Ability to adapt to structural changes.4.

Hence if a patient lacks occluding molars, has ad-

equate function, no progressive shifting of teeth,

no subjective complaints about lost teeth and

pathological changes are unlikely to be caused by

this type of partial edentulism, why should den-

tal prostheses be provided? Ethical concerns may

also include the costs associated with unneces-

sary provision of removable partial dentures, fixeddentures and implant supported prostheses and

it could be argued that for this specific case, that

the best dentistry is probably “no dentistry” (Fig-

ure 2) (Sheiham, 2002).

Dental practice has previously been guided by

mechanical concepts and there was a widespread

belief that only the rehabilitation of former oc-

clusal morphology would provide ideal conditions

for our patients. This was called the “28 teeth

syndrome” and in the majority of situations is in-

appropriate (Käyser, 1989; Owall et al., 1997). The

search for such an occlusal scheme underesti-

mates the adaptive ability for each patient. As an

example of adaptation, it was found that the loss

of molars results in controlled incidence of force

by the masticatory muscles and overloading of

the TMJs does not occur as a consequence (Hat-

tori et al., 2003). This illustrates the physiological

potential for adaptation of the stomatognathic

system. If the human body adapts itself after sur-

gery or trauma by means of complex mechanisms,

it would be naïve to think that oral health would

not adapt itself to the damage imposed by the

loss of occlusal support. The SDA concept can be

justified by this premise, as it summarizes a suc-

cessful response by the stomatognathic system

to adverse factors.

majority of participants were

able to adapt adequately. The

retention of anterior teeth, pre-

molars and a pair of occluding

molars (such as, 16 and 46) canprovide satisfactory mastica-

tory function. In general, Brazil-

ian people have illustrated their

satisfaction with SDA schemes;

good results were achieved with

the preservation of anterior

teeth and three pairs of occlud-

ing premolars. Moreover, in the

majority of participants the SDA approach proved

to be more satisfying than the replacement of

lost teeth by removable partial dentures (Elias &

Sheiham, 1999).

The loss of teeth has also been implicated as a pos-

sible cause of temporomandibular disorders (TMD)

with the expectation that these disorders would

be more prevalent as a consequence of the loss

of posterior teeth. An observational study found

an association between missing teeth and articular

pain (Ciancaglini et al., 1999). However, the associa-

tion was discrete and insignificant for participants

with a small number of missing posterior teeth.

It can be reasonably assumed that TMD, as with

nutritional problems, is associated only with ex-

tensive loss of occlusal support. Clearly, the stom-atognathic system is capable of adequate func-

tion if premolars and anterior teeth are present,

but further shortening might be associated with

orofacial pain (Budtz-Jorgensen et al., 1985).

The association between the number of teeth

in occlusion and signs or symptoms of TMD has

not been confirmed by all investigators (Mejersjo

& Carlsson, 1984) which appears to indicate that

occlusion may only be a peripheral factor in the

etiology of TMD. A clinical trial by Witter and col-

leagues (Witter et al., 1994) showed that the loss

of molars is not a risk factor for TMDs. This ap-

pears to confirm that the absence of molars is not

relevant to the development of muscular and joint

TMD, as long as the insertion of removable partial

dentures was not able to prevent TMDs in part of

the sample. It can be concluded from this report

that the return of molar support was similar to no

intervention if we consider the prevention of TMD

as the desired effect. It would be safe to assume

that the participants would be most likely to de-

velop TMD regardless of the presence or absence

of molars.

Clearly the stomatognathic system does not need

to adhere to the “criteria for ideal occlusion” for

being physiologically acceptable, providing it con-



Smile Magazine www.smile-mag.com22

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The Shortened Dental