152 volume 14 • issue 2 April / June 2010 •

AbstractThe paper aims at focusing, in the context of the com-

plications occurring in partial edentation, of a specialpathology, manifested in lateral intercalated edentationof the arch, namely the distal molar tooth syndrome ofthe potentially prosthetic space, which shows an interest-ing behaviour,with several pathological consequences.

The syndrome of the distal molar tooth, more fre-quently occurring on the mandible than on the maxilla, isa result of teeth natural displacement, as well as of theirtendency to mezialization.

Installation of the distal molar tooth syndrome is evi-dent in the molar and neighbouring teeth displacementtowards the edentulous space, by extrusion of the an-tagonistic molar tooth, modifications of the marginal andsupporting periodontium, as well as by axis and occlusalside disorders, accompanied by installation of occlusaltrauma, and of disfunctional symptoms of articular, mus-cular, mandible-skull relations, mandibular dynamics,etc.

The present study establishes several correlations be-tween the displacement of the distal molar tooth axis andits dental mobility, depth of the mezial pockets and gin-gival inflammation, on an experimental group made upof 239 patients, out of which 187 showed lateral reducedintercalated partial edentations on the mandible and 52on the maxilla. There was also evidenced the presence,within the distal molar tooth syndrome, of symptomsaccompanying partial edentation at muscular and articu-lar level, centric and posture relations, mandibular dy-namics, etc.

The results obtained lead to the conclusion that themore marked displacement of the distal molar tooth axisis accompanied by its increased mobility, by a higherdepth of the mezial periodontal pockets and by more in-tense gingival inflammation.

The complexity of the clinical manifestations, togetherwith the occurrence of the distal molar tooth syndromerequires therapeutical solutions to be found immediately,in post-edentation initial stages. Immediate prosthesisapplication, be it conjunct or adjunct, may restore the con-tinuity of the damaged arch, thus preventing the com-plications of partial edentation.

If such a moment is lost and the distal molar toothsyndrome is already installed, the treatament will be con-ducted towards the recovery of the morpho-functionalintegrity of the stomatognate system, by taking care ofthe muscle-articular complex, mandible-skull reposi-tioning, recovery of the distal molar tooth through ortho-

THE SYNDROME OF THE DISTAL MOLAR TOOTH

V. Burlui1, Carmen Stadoleanu1, Corina Cristescu2

1 Prof. PhD, Dept. Prosthetic Dentistry, Fac. Med. Dent., U. Apollonia of Iasi1 Prof. PhD, Dept. Prosthetic Dentistry, Fac. Med. Dent., U. Apollonia of Iasi2 Lect. PhD, Dept. Prosthetic Dentistry, Fac. Med. Dent., ”Gr.T.Popa” University of Medicine and Pharmacy IasiCorresponding author: Carmen Stadoleanu; e-mail; drcarsta@yahoo.com

dontic procedures in young patients, followed by long-term gnato-prosthetic treatments.

Keywords: distal molar tooth, syndrome, partial in-tercalated reduced edentation, complications, treatment

Local, local-regional and general complica-tions of the reduced partial intercalated edentionhave a negative effect on the quality of humanlife. Usually, they begin with odonto-periodontaloverstress (abrasion and tooth mobilization),migrations of the neighbouring and antagonisticteeth, loss of the central occlusal stops, up toarticular and muscular disorders, impairment ofmandibular dynamics and deficient mandible-skull relations (1, 2).

The pathological picture of partial edentationcomplications is characterized by a series of sym-ptoms which support the idea that the clinicalsigns manifested demonstrate the installation ofa distal molar tooth syndrome, much morefrequently distally to the potentially prostheticspace (1,3) –Fig.1.

Reduced partial intercalated edentation mayevolve in two directions: towards compensationand re-establishment of the stomatognated sys-tem homeostasis or towards immediate or de-layed installation of its dishomeostasis. In thisway, all components of the prosthetic field andof other elements at a distance (temporal-mandi-ble articulation, the muscles mobilizing the man-dible) are modified, to a lower or higher extent.

At tooth level, slow mechanical wear offoccurs, as a result of overstress, thickening of thecement layer deposited on the roots of the over-used teeth, in taking over the functions of themissing teeth. The number of periodontal fibersincreases, thus granting a better tooth implan-tation, while the tough lamina of the remainingteeth and from the neighbouring area becomes

Prosthetic Dentistry

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Journal of Romanian Medical Dentistry 153

thicker. Marginal gingiva becomes also thickerand tougher. At the level of the edentated ridge,the compensating stage appears as a bone trabe-cular area, organized according to the directionof the stressing forces (usually, parallel to theedge of the crest, towards the adjacent teeth).

Fig.1 –Local complications of reduced partialintercalated edentation (3)

In this stage, conjunct prosthesing has a fa-vourable diagnosis, as long as it does not induceadditional disequilibria, as a result of an unsui-tably-distributed stress (2).

In patients with viciated general conditionand deficitary local metabolism, as well as in thecase of unsuccessful prosthesis operations, theevolution towards decompensation is irrever-sible, being first manifested at the level of thesupporting tissues where they occur, due to:increased mobility, pathological deepening ofthe sulcus, enlargement of the periodontal space,disappearance of lamina dura, modification ofbone trabecular area, etc. Such phenomena arealso generated by edentation itslef, which de-stroys the interdental contact point, thusexposing the interdental papilla to the shock of adirect contact with food (1).

When local disequilibrium is amply mainfes-ted, its effects go beyond the very local area,occurring as dishomeostasis of the whole sys-tem, and leading, slowly but irreversibly, to-wards significant complications of partial (local-regional or general) edentation.

Local complications are represented by abra-sion of the remaining teeth, overstress, perio-dontopathy, abnormal tooth mobility, manifes-tation of dental migrations (bascular modifi-cations, involving modification of the dentalaxis, parallel to the dental axis, axial migrationswith migration of the alveolar bone or not, etc.(2) – Fig.2).

Fig. 2 Extrusion of the first maxilla molar and mezialdrifting through basculation of the secondary

mandible molar, following molar tooth extraction ofthe first mandibular molar tooth (2).

Local-regional complications result frommandibular-skull malposition, following partialedentation, which will affect the normal posture,the centric and occlusion relations.

Severe alteration of such parameters will leadto dishomeostasis, manifestation of the disfunc-tional syndrome of the stomatognate systemaffecting ATM (pain, deterioration of elements,articular blocking, subdislocations), mandibularmuscles (spasm, hypertrophies, hyper- or hypo-tonies, pain), mandibular dynamics (malocclu-sions), occurrence of parafunctions (bruxism).

In an initial stage, all these complications arereduced while, in time, and in the presence ofsome favourizing factors, the situation becomesmore serious, especially for the distal molartooth of the edentulous space. That is why, theprosthetic treatment is is considered to be com-pulsory, even in the absence of a single lateraltooth (1).

The present paper discusses a pathology, in-dividualized among the complications inducedby partial edentation, manifested as lateral

V. Burlui, Carmen Stadoleanu, Corina Cristescu

154 volume 14 • issue 2 April / June 2010 •

intercalated edentation of the arch, namely: thedistal molar tooth of the potentially prostheticspace, whose unusual behaviour induces nu-merous pathological consequences.

The syndrome of the distal molar tooth,more frequently occurring distally, on themandible rather than on the maxillary, resultsfrom teeth natural displacement – Fig.3, as wellas from their tendency towards mezialization (3).

Fig.3 Cone of dental axes converging towards Cristagalli

The central and lateral mandibular incisorsare almost vertical, displacement being moreand more marked distally.

The displacement degree of tooth occlusalsides is reflected in the sagital curve of Spee(concave at the mandible, convex to the maxilla):the teeth from the posterior half of the curve willbe displaced more in anterior direction – Fig.4.

The transversal curve of Monson and Villainreflects displacement of the mandibulary lateralteeth towards the lingual area –Fig.5. Byprolonging the axes of the mandibulary andmaxillary teeth, one may observe that they getunited at the level of the apophysis. Crista galliof the frontal bone forms a cone defined byVillain as a supporting cone. The posible spatial

Fig. 4 Spee curve and formation of the occlusion plane

Fig.5 Displacement of dental axes - Villain supportingcone

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THE SYNDROME OF THE DISTAL MOLAR TOOTH

Journal of Romanian Medical Dentistry 155

obtention of the supporting cone results fromthe sum of the dental degrees of displacementtowards the vertical line, each tooth having anatural displacement of its own, in mezio-distaland vestibulo-oral position. Such an individualdisplacement represents another morphologicaladaptation to the occlusal forces, periodontalprotection being achieved through dispersion ofthe resultant forces.

Installation of the distal molar syndrome isevident in molar displacement, displacement ofthe neighbouring teeth towards the edentedspace, extrusion of the antagonistic molar tooth,modification of the marginal and supportingperiodontium, as well as through axis andocclusal side disorders.

1. Displacement of the distal molar toothoccurs in the case of older edentations, in you-nger subjects, in whom bony plasticity allowsits facile and more rapid migration (Fig.6).

Fig. 6 Angle formed between tooth axis and theocclusion plane

2. Displacement of the neighbouring teeth andextrusion of the antagonistic molar tooth appearsas an immediate consequence of the limitrophetooth migration towards the edentated prosthe-tic space and of the antagonistic tooth towardsthe establishment of new occlusal contacts.

3. The complications occurring at the level ofmarginal periodontium result from the modifica-tions induced at proximal contact level, which arequite usual in the etiology of periodontaldiseases. The point of distal contact dissapears,as a result of distal molar tooth displacement,while the neighbouring molar tooth may be en-gaged in the distal convexity, blocking the inter-dental contact in a pathological manner, whichdoes not protect gingival papilla any more, pro-ducing instead retention and food setting (4).

Twisting of the mandibulary molar teeth andextrusion of the maxillary ones modify the inter-proximal contacts of these teeth. The distalcuspides of the second inferior molar tooth areover-high, thus depositing food in the inter-proximal space between the first upper molartooth in extrusion and the second superior molartooth (5,6).

Towards mezial position, coronary displa-cement creates retention zones for the plaque(the tooth is laid down horizontally on the gum),which cannot be removed by the usual methodsof oral hygiene. Consequently, a periodontalpocket results, causing destruction of the meziallamina dura, followed by persistence of the perio-dontal pocket, through the inflammation causedby bacterial plaque accumulation.

At the level of the supporting periodontium,bone aposition in the distal zone and boneresorption in the mezial zone occur, while thealveolar margin is destroyed towards theedentated zone (7).

4. Disorders of axis and of occlusal side –occlusal trauma

The occlusal forces increase tooth displace-ment. When they exceed the physiological limits,causing tissular problems, the “ occlusal trauma”occurs - Fig.7. Displacement of the cuspidianplanes also occurs, causing severe occlusaldisorders. The insufficient transmission of theocclusal forces, induced by the absence of teeth,

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produces pathological atrophic modificationsdefined as “periadonthal atrophies due tohypofunction”(8,9).

Fig.7 Occlusal trauma – a comparison between thedistribution of the masticating forces per completedental-periodontal units (primary trauma) and a

periodontal disease (secondary trauma)

Mezial drifting of the distal molar tooth fromthe edentated space causes loosing of the mezialcontacts with the antagonistic units and inten-sifies the distal contacts while, at the level ofantagonistic ones, extrusion of cuspides con-tacting the mezial cuspides of the distal molartooth and intrusion of the other half occur. In theabsence of the mandibular first molar tooth, onemodification involves shifting and twisting ofmolar teeth 2 and 3, as well as extrusion of thecorresponding upper molar tooth - Fig.8.

The malocclusion thus installed may increasethe para-functional vicious habits – such as con-traction of the raising muscles, and teeth stret-ching and blocking. As a function of their inten-sity and durations, such parafunctions releaseforces which exceed the adaptation capacity ofthe periodontium, leading to occlusal trauma (10).

The syndrome of the distal molar tooth isalso accompanied by symptoms of partialedentation, such as: the tongue increases involume and enters the potentially prostheticspace (Fig. 9), the print of the teeth appears onthe lateral sides (Fig.10), over which the cupeffect of the cheek mucous membrane whichcreates a prolapse towards the edentulous space(diapnesis) occurs.

Fig. 8 – Local complications of partially intercalatedreduced edentation (3)

Fig.9

Fig.10

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THE SYNDROME OF THE DISTAL MOLAR TOOTH