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m esoderm ic cells are necessary.” I t is im perative that a sm all am ount o f dentin be deposited before amelogenesis can be initiated. A p paren tly, the m esenchym al osteoid-like m aterial furnished the stim ulus necessary to activate the enam elform ing cells o f th e neoplasm . b ib l io g r a p h y
1. C h i l b r e t , A .: Etude Anatomo-Pathologique D ’un Cos D ’Epithelium. Arch, de Med. exper. et d’ anat. path., Paris, 6:248, 1894. 2. B e r n a y , A. C .: Cystic Tum or of Jaw in Negro. Some New Observations on Patholog ical Histology of the Disease. New York M. Rec., 2 8 :i, 1885. 3. D ’ A u n o y , R., and Z o e l l e r , A . : A da mantine Epithelioma. M. J. & Rec., 130:2 74, September 4, 1929.
4. M u m m e r y , J. H . : and P i t t s , A. T .: Melanotic Epithelial Odontome in Child. Brit. D. J., 4 7 :i2 i, February 1, 1926. 5. G h o s h , L. S .: Adamantinoma of Upper Jaw. Am. J. Path., 10:773, November 1934. 6. S c o t t , G . H . : Critical Study and R e view of Methods of Microincineration. Proto plasma, 20:133, October 1933. 7. S c o t t , G. H ., and P a c k e r , D. M. : Elec tron Microscope as Analytical Tool for Local ization of Minerals in Biological Tissues. Anat. Rec., 7 4 :17, M ay 25, 1939. 8. H am p p , E. G. : Mineral Distribution in Developing Tooth. Anat. Rec., 7 7 :273, July 25 , 1940 9. S c o t t , G. H . : Distribution of Inorganic Salts in Adult and Embryonic Cells and Tis sues. Cancer Probl. Symposium, 4:173, 1937 10. K r o n f e l d , R u d o l f : Adamantinoma. J. A .D .A., 17 :6 8 1, April 1930.
PROBLEMS IN PARTIAL DENTURE SERVICE B y C a r l O . F l a g s t a d ,* D .D .S ., M inneapolis, M in n., and F r e d C . E l l i o t t , f D .D .S ., H ouston, T exas
R . E L L I O T T : W hat are the m a jor problem s associated with par tial denture service? D R . F L A G S T A D : P artial dentures are a liab ility to the health of the m outh because o f the d ifficulty o f solving the follow in g p ro b lem s: (a ) Securing and m ain tainin g eq u a l ized stress betw een the n atu ral and the artificial teeth. (b) T h e danger o f in ju ry to a b u t m ent teeth from the attachm ents.
Topic discussion presented before the Sec tion on Partial Denture Prosthesis at the Eighty-Third Annual Meeting of the Ameri can Dental Association, Houston, Texas, O cto ber 29, 1941. •Professor of denture prosthesis, University of Minnesota, School of Dentistry, Discussor. fProfessor of dental prosthesis, Texas Den tal College, Leader. Jour. A .D .A ., Vol. 29, October 1, 1942
(c) Increased uncleanliness and lia b ility to inflam m ation because o f the presence o f the p artial denture. T h e operator should recognize these problem s w hen advising and designing partial dentures. D R . E L L I O T T : W hat examination and records should be made, prior to tak ing an impression for a partial denture? DR. FLA G STAD : (a) C om plete x-ray pictures are essential to diagnosis. (b) A record should be m ade o f the diagnostic exam ination and the m outh history. (c) S tu d y m odels are desirable, espe cially if construction is com plicated. (d) T h e financial status o f the patient should be determ ined so that a restora tion w ithin his financial means m ay be planned. (e) T h e fees agreed upon should be
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definitely recorded, to avoid fu tu re mis understandings. D R . E L L I O T T : W hat are some of the practical suggestions for designing partial dentures? D R . F L A G S T A D : (a) A decrease in tissue area to be covered necessitates an increase in the num ber o f rest lugs and supports on the rem aining teeth. (b) O n ly necessary retention should be planned; (c) T h e teeth most favorable fo r a t tachm ents as regards health, location, structure and appearance should be selected. (d) T h e applian ce should be so de signed th at it can be w orn w ith safety and the greatest com fort to the patient. (e) T h e design should m inim ize u n cleanliness and inflam m ation. D R . E L L I O T T : Is it possible to se cure balanced occlusion and m aintain it in partial dentures? D R . F L A G S T A D : I t m a y be possible to secure balanced occlusion a t the tim e o f insertion of the partial denture, b u t to m aintain it fo r any len gth o f tim e is alm ost impossible. E ven in favorable types o f p artial dentures, in w h ich sufficient lugs and stops can be placed, the o cclu sion w ill gen erally change, because the m etals w ill bend and the abutm ent teeth w ill intrude and shift. D R . E L L I O T T : H ow can possible injury from undue stress to abutm ent teeth be m inim ized? D R . F L A G S T A D : P roperly con structed attachm ents, lugs and stressbreakers, and frequent observation a fter the denture has been inserted, w ill reduce the possibility o f injury from stress. D R . E L L I O T T : H ow does partial denture service compare in efficiency with other branches o f restorative dentistry? D R . F L A G S T A D : I f liab ility and risks involved are considered, it com pares reasonably w ell. T h e necessity for p a r tial dentures frequently arises at the b e gin nin g o f the period o f greatest destruc
tion in the m outh, from progressive dis ease. I t is questionable w hether the subsequent loss o f teeth is ch argeable to the w earin g of partial dentures or to certain system ic destructive processes w h ich it seems im possible to control. D R . E L L I O T T : W hat are some of the factors in determ ining the length of service a partial denture w ill render? D R . F L A G S T A D : L en g th o f service m ay be determ ined by : (a) T h e m outh history. H a ve there been caries, disintegration and disease, or has the m outh been h ealth y? (b) T h é system ic health. (c) T h e type of construction re quired. (d ) T h e m outh hygiene. T h e habits of oral care are w ell form ed at the time w hen p artial dentures becom e necessary, and the chances are th at they w ill not chan ge g rea tly in the future. (e ) T h e present condition o f the m outh and teeth. D R . E L L I O T T : W hat . impression technics apply to partial dentures? D R . F L A G S T A D : C o m p o u n d ; plas ter and pastes ; elastic m aterials, and a com bination o f m aterials are used. A n impression technic is efficient in prop or tion to the operator’s judgm en t, skill and vision. D R . E L L I O T T : W hat o f the reten tion o f partial dentures and the requisites for an attachm ent? D R . F L A G S T A D : T h ere are two general means o f retention fo r partial dentures : clasps o f various types and slotted attachm ents o f different kinds. T h e requisites o f attachm ents are : ad equ ate retention, y et not locking the d en tu re; m inim izing o f danger o f dis integration and disease o f abutm ent teeth ; sufficient spring to perm it resil ien cy o f tissue, and ad equ ate strength. D R . E L L I O T T : W hy does the partial denture require more servicing than any other type o f dental restoration? DR. FLA G STA D : (a) T h ere is
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greater d anger of dam age to the denture and the rem ain ing natural teeth. (b) T h e construction is m ore delicate and c o m p lic a te d ; w h ich increases the liab ility to distortion and breakage. (c) T issue changes frequ en tly alter the relation o f dentures and the a tta ch m ents to the n atural teeth so th at ad ju st ments are necessary. (d ) Disease m ay develop in the re m aining teeth and m ay require rem oval o f the tooth or teeth, w ith the necessity o f m akin g additions to the denture. D R . E L L I O T T : W hat m ajor diffi culties that develop in partial dentures over a period o f tim e require service? D R . F L A G S T A D : T h e follow in g are com m on d ifficu lties: (a) A d d in g teeth to the p a rtial denture, (b) Settlin g of the p artial denture, (c) Im pingem ent o f bars an d saddles on tissue, (d) B reak age o f attachm ents and their rep lace ment. D R . E L L I O T T : In partial denture cases, how can the bite be opened and m aintained? W hat are the lim itations? D R . F L A G S T A D : I t is im possible to open a b ite w ith a p artial denture and m aintain it very lon g unless the opposing n atural teeth are b u ilt u p to the desired level w ith crowns and in lay or overlay lugs. U su ally, it m ust include a num ber o f such teeth since there m ust be suffi cient b earin g on the n atu ral teeth to con trol the tend en cy to intrude. T h e lim itations on opening a bite on a p a rtial denture w ill depend on the safety lim it to w hich w e can build up the n atu ral teeth or to w hich w e can reposition the low er ja w in relation to the upper. D R . E L L I O T T : W hat is the con sensus o f opinion regarding the choice of base m etals for partial dentures and also the substitutes for vulcanite? D R . F L A G S T A D : T h e general op in
ion is th a t the base m etals, such as vitallium , ticonium and w ipla, are superior in m any respects to the gold alloys because o f the follow in g q u a litie s: (a ) Perm a nency o f color, due to freedom from oxi dation. (b) Strength, (c) W eigh t, (d) Cheapness. T h e disadvantage o f the base m etals is the in ab ility to process it in the aver age d ental office. T h is has given m uch concern to the profession because it has m ade possible the control o f m aterials and technics b y com m ercial firms. T h e acrylics are a satisfactory substi tute fo r vulcanite. D R . E L L I O T T : W hat are the chief causes for rapid resorption o f tissue under partial dentures and how is it possible to control it? D R . F L A G S T A D : T h e causes a r e : (a) O verretention, locked retention (b) Stress o f occlusion, chiefly on partial dentures. (c) T y p e o f tissue and the tissue area covered. It can be partially controlled b y : (a) E qu alized occlusal stress between n atu ral and artificial teeth on insertion o f the denture. (b) Proper placin g o f lugs and stops. (c) Frequent observation o f the case so th a t necessary adjustm ents to ch an g in g conditions can be m ade. D R . E L L I O T T : H ow should a pros pective partial denture patient be advised concerning this service? D R . F L A G S T A D : A patien t should be honestly apprised o f the liabilities associated w ith the p artial denture and this inform ation should be based on a carefu l diagnosis o f all the factors. T h e decision as to the type o f p a rtial denture to be inserted should not rest upon the p atien t’ s ability to p ay, but rath er on the m erits o f the service th at the denture will render.