A manual of dental mechanics

Front matter

uj'n*

ill

A MANUAL

Preface

The present work makes no pretence to originality, and is intended for the Student rather than the Practitioner.

Within the bounds of a handbook I have endeavoured to give information of a purely practical nature upon all matters relating to Dental Mechanics, excluding, as far as possible, everything of doubtful value or merely theoretical interest. I may have carried my attempt at brevity to an extreme extent, but noting the present rage for “ big books,” this is a fault that I trust will be forgiven in a work that is entitled ‘ A Manual,’ and should not, therefore, extend beyond moderate limits.

To the questions of the greatest interest vm

PREFACE

I liave devoted . the most space, while many details I have passed over with hut brief notice, since they can only be properly acquired in the Dental Laboratory.

I have collected information from many different sources, and have given the knowledge thus obtained, as far as possible, in the words of the original author, so that proper credit may be awarded where it is due. To my American brethren I am under deep obligations for valuable investigations and new facts in the Science of Dentistry.

To Mr S. S. White, of Philadelphia, my thanks are due for the great good nature with which many woodcuts for illustrating the present work have been supplied.

To Messrs Ash and Sons, and Mr G-. W. Rutterford, of this city, and Mr Fletcher, of Warrington, I am also indebted for similar courtesies.

I am especially obliged to Mr G. H. Makins for the readiness with which he not onfy supplied me with illustrations for the section on “ Assaying,” but also sent notes of the additions

PREFACE

IX to the letter-press that he proposed making to the second edition of his work on ‘ Metallurgy.’ In conclusion, I may state that this volume has been prepared during spare moments in the course of heavy professional work, and on this account I would ask that it may, in some respects, be leniently judged by my critics and readers ; at the same time I trust it will be found useful by those for whom it was especially intended.

81, Wimpole Street, Cavendish Square ; March 2bth, 1873.

PAGE

Dedication ...... v

Preface ....... vii

List of Illustrations .... xxiii

Section I Preparation Of The Mouth For Artificial Teeth

Removal of Diseased Stumps and Teeth . . .1

Removal of Tartar, and Treatment of Caries . . 2

Length of Time after Extractions that should elapse before Inserting Artificial Denture . . .3

Section II On Taking Impressions

Best means of Softening and Filling Impression Tray . 6

Introduction of Tray and W ax into the Mouth . . 7

Removal from the Mouth . . . . .7

Plaster of Paris . . . . . .7

Mode of Mixing and Introduction into the Mouth . 8, 9 Hind’s Composition . . - . .9

Cases in which it is most useful . . .10

The best way of Softening and applying in the Mouth . . . . . . .10

Xll

PAGE

Stent’s Composition, Gutta Peecha, Wax and Paraffin, their special characteristics . 10, 11

Impression Cups and Trays . . . .11

For Plaster of Paris Impression . . . .11

For Plastic Material . . . . . .12

For Lower Impressions in Plaster . . . .13

For Lower Impressions in other Materials . . .14

SECTION III THE various modes of applying heat employed in

THE DENTAL LABORATORY

The Common Blowpipe, description of . . .16

Blowpipe, with Bulb attached, for Checking Flow of Moisture . . . . . . .17

Bellows’ Blowpipe . . . . . .17

Burgess’ Blowpipe . . . . . .18

Owen’s Blowpipe, with Gas Supply attached . . 19

Snow’s Blowpipe, with Gas Supply attached . . 19

Fletcher’s Blowpipe . . . . . .20

Fletcher’s Hot-blast Blowpipe . . . .20

Self-acting Blowpipe (English) . . . .21

Self-acting Blowpipe (American) . . . .22

Self-acting Blowpipe (French) . . . .22

Gas Burner for Blowpipe Work . . . .23

Oil Lamp for Blowpipe Work . . . .23

Spirit Lamp for Blowpipe Work . . . .24

Structure of Hand Furnace . . . . .25

Fire-Clay Furnace for Melting Precious Metals . . 26

Fletcher’s Gas Furnace for Melting Precious and other

Furnace for Continuous Gum Work, heated with Anthracite Coal . . . • • • ,28

Xlll

Section IV Casting In Plaster Of Paris And Metal

PAGE

Casting Model in Plaster from an Impression taken with.

any Plastic Material . . . . .29

Preparation of the Impression, Strengthening of Teeth,

Use of Galvanised Iron Wire and Wooden Pegs . 29 Shape of Model for Metal Work . . . .30

» ,, Vulcanite Work . . .30

Removal of Impression from Model . . .31

By means of Hot Water or Dry Heat . . .31

Casting a Model from a Plaster Impression . . 31

Preparation of the Surface of the Plaster . . .32

Separation of the Impression from the Model . 32, 33

Trimming-up of Plaster Models . . . .33

Preparation of Plaster Models for Gold Work . . 33

Casting in Metal ......

Description of Casting Sand to be used . . .34

Mode of Moistening with Oil or Water . . . 34

Coating Model with French Chalk . . . .35

Use of Iron Casting Ring . . . . .35

Pouring of Molten Metal into Mould . . .35

Hawes’ Casting Ring for Undercut Models . . 36

Franklin’s mode of Casting Dies and Counter-dies . 37

Counter-die obtained from a Ladleful of Lead . . 40

„ Casting Ring and Sandbank 41

„ Impression of Plaster Model dipped in Lead . . . . . .41

Casting Model from Lead Counter-die . . . 42

Materials for Metallic Castings . . . .42

Composition of various Fusible Metals . . . 42

Professor Austen’s Table of Fusible Metals . . 43

Annealing Dies and Counter-dies . . . .43

X1Y

Section V Precious Metals Used In Dentistry

PAGE

Gold, its Equivalent, Specific Gravity, Melting Point, and

General Properties . . . . .44

Alloys of Gold with Copper . . . . .45

„ „ with Silver and Copper . . .45

„ ,, with Silver, Copper, and Platinum . 45

On Assaying Gold Alloys .... 46 — 62

Melting Gold . . . . . .62

Admixture of Flux . . . . . .62

Pouring the Metal . . . . . .63

Treatment after Pouring into Ingot . . .63

Forging of Ingot . . . . . .64

Flatting of Ingot into Sheet . . . .65

Use of Gauge to test the thickness of Meta,. . . 65

Necessity of frequent Annealings . . . .65

Means to be Used for obtaining the best results in preparing Gold Plate . . . . .66

To Melt a small quantity of Metal by means of Charcoal

Wire Making, preparation of Gold for . . .67

Use of Forging . . . . . .67

„ Draw Plate . . . . . .68

Spiral Springs, method of Making . . . .69

Silver, its Equivalent, Specific Gravity, Fusing Point,

and General Properties . . . . .69

Solubility in Acids . . . . . .69

Alloys, with Platinum — Dental Alloy . . .69

„ with Copper . . . . . .70

Platinum, Equivalent, Specific Gravity, Fusing Point, and

General Properties . . . . .70

„ principal Alloy with Gold . . .70

Solder for Platinum . . . . . .71

XV

Section VI Making Gold Plates For Partial And Entire

DENTURES

Taking a Pattern for Plate

PAGE

. 72

The Teeth to which Bands may be Fitted Shape of Plate for single Tooth-case Advantage of leaving the Palate exposed Striking-up Gold Plate to Zinc Model Tools used for this purpose .

Necessity of Annealing Plate during this Process The use of Hydrochloric or Sulphuric Acid before An nealing ....

The necessity of having several Models Fitting round the Teeth with Chasing Punches Mode of Filing-up Plate ....

Repair of Cracks and Fractures in Plates .

Strengthened for weak parts of Plate

Bands and Clasps ....

Manner of Fitting ....

Dr. Spalding’s “ Standard ” Clasp .

Soft Platinum Clasps stiffened with Gold .

Fitting Clasps to Plate and Mouth ,

Use of Resin and Wax for attaching Clasps to Plate foi trying in .

Use of Sealing Wax for the same purpose .

Use for Plaster and Sand for same purpose Removal from the Mouth when in position Soldering on Bands and Clasps Lower Plates .....

Teeth most suitable for Fitting Bands to .

Strengthener for lower Gold Plate .

Various forms of lower Plates

Edges of lower Plates ....

Suction Plates .

80 81

85 85

XVI

PAGE

The use of Atmospheric Pressure . . . .85

Air Chambers . . . ... . .85

Their various Forms and Manner of Making . . 88

Making Plates for Comflete Upper Dentures . 87 Form of Plate for Suction . . . . .87

Form of Plate if used with Spiral Springs . . .87

Dr. Kurras’ Clamp for holding Plate while beating into

Manner of applying a direct blow to Die by Weight

Apparatus . . . . . .89

Cleveland’s Suction Chambers for full Upper Dentures . 90

Mode of constructing . . . . .91

Making a Plate for complete Lower Denture . . 92

Manner of Strengthening and Finishing . . .93

Obtaining the Bite for a Partial Denture . 93

(1) With Upper and Lower Models ready for use . . 93

(3) “ Extension ” Bite . . . . .96

Central and Horizontal line of Mouth, manner of obtaining . . . . . . .97

Obtaining the Bite for an entire Upper and Lower

By means of Blocks of Wax . . . .98

By watching the Movements of the Jaws . . .98

With the Teeth Mounted on the Plates with Cement . 98 Rule for the Depth of the Bite . . . .99

Use of the Adjustable Articulator . . . .99

Section VII On The Various Forms Of Porcelain Used In Mechanical Dentistry

Composition ....... 102

Mode of Manufacturing Single Teeth . . .103

Moulding, Enamelling, Baking .... 101

XVII

PAGE

Receipts for Making Body and Enamel . . . 105

Colours produced by Metallic Oxides . . . 105

Method of Preparing Sectional Blocks . . . 106

Composition for Body of Block Teeth . . . 107

„ „ Enamel ditto .... 108

„ of Flux used ..... 109 Manner of Preparing the Ingredients for use . . 109

Continuous Gum Work ..... 110 Dr. Allen’s Mode of Practice in Continuous Gum . .111

Section VIII Pivot Teeth

Cases most suitable for Pivoting .... 124 Condition of the Stump . . . ‘ .125

Preparation for Reception of Pivot .... 125 Treatment and Removal of Nerve .... 127 Preparation of Pulp Cavity ..... 127 Taking the Impression for a Pivot Tooth . . . 128

Fitting the Artificial Crown to the Stump . . . 128

The choice of a Tooth for a Pivot Case . . . 129

Varieties of Teeth used in Pivoting — 1. Pivot Tooth;

2. Tube Tooth ; 3. Flat or Plate Tooth . . 129

Their several advantages discussed .... 130 Preparation of the Model, and Fitting the Tooth . .130

Affixing the Pivot ..... 132, 133

Section IX Choosing And Adjusting Mineral Teeth

For partial Cases ...... 135

For entire Denture ...... 135

Fixing Teeth to partial Cases . . . 136

Teeth fitted on Stumps or the Gums . . 136

b

CONTEXTS

PAGE

Arrangement of Bite in Eccentric Cases . . . 137

Raising the Bite ...... 137

Investing the Case in Plaster and Sand, or Asbestos . 138 Fitting on Backings to Flat Teeth .... 139

c Preparing for Soldering ..... 140

Heating up in Hand Furnace .... 141

Soldering by means of Blowpipe .... 141

„ Full Sets of Teeth ..... 141

Various means for Preventing the Plaster Cracking . 141 Finishing up and Polishing the Case after Soldering . 142 Fitting Tube Teeth to a Full Set .... 143

Use of Moulds for retaining the Teeth in position during

this Process ...... 144

Fixing Tube Teeth to the Pins on the Plate . . 145

Section X The Vulcanite Base

The purest Dental Rubber ..... 146

Professor Wildman’s Experiments .... 147

Admixture of Caoutchouc with Sulphur and Colouring

Solvents of Caoutchouc ..... 147

Manner of Preparing the Rubber for Experimental Purposes ....... 149

Caoutchouc and Sulphur alone — Result . . . 149

Colouring Properties of Red Oxide of Hon . . 150

Vermilion for producing Red .... 150

To produce a Yellow Rubber .... 151

„ „ Light Yellow . . . . .152

Variations of the above ..... 153

To produce a Black Rubber ..... 155

Table showing the Proportion of Caoutchouc in the

various Rubbers sent out by different Manufacturers 157

XIX

PAGE

The Composition of Ash & Son’s S. P. Rubber . . 158

Table showing the Percentage of Fixed Matter in different Rubbers ...... 159

The Properties of Vulcanite . . . 161

The use of Vulcanite in Dental Surgery and Mechanics . 162 Injurious effects upon the Mouth attributed to the use of Rubber ....... 163

General Instructions as to Vulcanising . . . 164

Cause of Porosity in Rubber Dentures . . . 164

Construction of a Full Upper Set of Teeth in

the Vulcanite Base .... 165

Base Plate of Thin Wax ..... 166

„ Sheet Gutta Percha .... 166

,, Waxed Blotting-paper . . . 166

„ Stent’s Process and Metal . . . 167

Arrangement of the Teeth on Plate . . . 168

Modelling up in Wax, Spatula; .... 169

Bell and Turner’s Flask ..... 170

Bennett’s Intervening Plate .... 170

American Flasks ...... 170

Sinking Case in Flask . . . . .171

Closing up Flask ...... 172

Opening the Flask, precaution to be taken . . 172

Clearing away Wax from Moulds .... 173

Packing the Rubber into Flask . . . 173

Arranging for Overplus . . . . .174

Closing the Flask . . . . . .175

Objections to Coating Surface of Plaster . . . 176

Vulcanizers ...... 176

Ash and Son’s Vulcanizer ..... 177

Whitney’s ditto ..... 178

Hayes’ “ Ironclad ” ditto ..... 179

Hoffstadt’s Self -regulating ditto .... 180

Rutterford’s *• Single Screw ” ditto . . . 182

XX

PAGE

Position of tlie Flask in the Vulcanizer . . . 183

Temperature for Ordinary Y ulcanization . . . 184

Cooling and Opening the Flask .... 184

Filing-up Yulcanite Piece ..... 187

Use of File-cut wheel for “ roughing up ” . . . 187

Use of Scorpers for Shaping-up round the Teeth . . 188

Finishing up with Scrapers, Glasspaper, and Ayrstone . 189 Polishing at the Lathe with Brushes . . . 189

Preparation op a Full Lower Set . . . 192

Partial Cases for the Upper Jaw . . . 192

Strengthening Teeth for partial Cases . . . 192

Use of Gold Bands to support partial Dentures . . 193

Use of Yulcanite Bands compared with Gold . . 193

Yarious ways of Fitting up Gold Bands for use in Yulcanite Cases ...... 194

Preparation of the Case and Model for Flasking . . 195

Strengthening a Vulcanite Plate by means of Gold Ridge 196 Form of Plate that is to be supported by Spiral Springs . 198 Repairing Yulcanite Plates ..... 198

Use of Modelling Clay to avoid Discoloration . . 199

Mode of Flasking a Repair ..... 199

Removal of Discoloration in Repaired Cases . . 199

To Re-set a Yulcanite Piece .... 200

To Set in Yulcanite an ill-fitting Gold Case . . 201

Manner of taking an Impression for same from the Mouth 202

Finishing off a Gold Case set in Rubber . . . 203

To Re-set Lower and Partial Cases . . . 204

To Improve the Colour of Vulcanised Rubber . 205

Section XI The Celluloid Base

Its Introduction and Preparation . . . 205

Varieties of Colour and Solubility .... 206

XXI

PAGE

Mode of Working for Dental Purposes . . . 208

Best form of Flask, Clamp, and Tank . . . 209

Action of Chemical Agents upon it . . , .211

Section XII The Treatment Of Deformities Of The Mouth

Congenital Cleft Palate ..... 214

Taking the Impression ..... 214

Making the Model ...... 220

Modelling the Artificial Velum .... 221

Making the Plaster and Metallic Moulds . . . 222

Rubber, and Time of Vulcanizing .... 225

Fitting a Hard Rubber Frontpiece .... 225

Account of Cases of Congenital Cleft Palate treated by the Author ..... 227-236

Treatment of Deep Palate ..... 238

Treatment of Projecting Intermaxillary Region . . 239

Syphilitic Perforations of Palate . . . 240

Taking the Impression ..... 243

Dividing Tray, use of ..... 244

Making the Palate Plates ..... 251

Cases treated by the Author . . . 253-8

Deformities arising from Phagsedenic Ulceration . . 258

Deformities of the Mouth arising from Mechanical Injury 258

Receipts for making Gold Plate of the various qualities most in use for the Mounting of Artificial Dentures . 261 Solders for Gold Work ..... 262

Brass Solder ....... 263

German Silver ...... 264

XXII

PAGE

Rose’s Fusible Metal ...... 264

Method of reducing Gold to a higher or lower Standard of Fineness, and of determining the Carat of any given Alloy . . . . . . .265

Dr. Hunter’s method of supporting Partial Dentures in the Mouth by means of Cylinders of Wood attached to Tubed Plates ...... 270

Table showing the Names, Colours, and Degrees of Heat required for Vulcanizing the Rubbers that are most used at the present time . . . .271

The Means to be adopted for obtaining Suction . . 272

Repairing Vulcanite ...... 272

To restore Vulcanite Cases to their first form . . 273

Spiral Springs and Swivels ..... 273

To- prevent Abrasion of the Cheek from Spiral Springs . 276

LIST OF ILLUSTRATIONS

The name in Italics placed against each Illustration indicates the source from whence it has been obtained, and in most cases that the article is manufactured or sold by the firm or person whose name appears, Mr. M akin s’ aloue excepted. The woodcuts without any name attached are either original or taken from works already published by the author.

FIG. PAGE

I, 2. Trays for full upper impression (Ash) . .11

3 — 6. Trays for partial upper impression (Ash) . 13

7, 8. Trays for lower impressions in plaster (Ash) . 13

9, 10. Trays for lower impressions (Ash) . . 14

11. Drainage blowpipe (Ash) . . .17

12. Foot-bellows blowpipe (.4s7i) . . .18

13. Burgess’ blowpipe (White) . . .18

14. Owen’s blowpipe (Ash) . . . .19

15. Snow’s blowpipe (Ash) . . . .19

16. Fletcher’s blowpipe (Fletcher) . . .20

17. Fletcher’s hot-blast blowpipe (Fletcher) . . 20

18. American self-acting blowpipe (White) . . 21

19. French self-acting blowpipe (Butterford) . . 22

20. English self-acting blowpipe (Ash) . . 22

21. Gas burner for blowpipe (Ash) . . ' .23

22. Oil lamp for blowpipe (Butterford) . . 23

XXIV

LIST OP ILLUSTRATIONS

FIG. PAGE

23. Spirit lamp for blowpipe (White). . . 24

24. Hand furnace (Ash) . . . .25

25. Asli & Son’s furnace for goid melting (Ash) . 26

26. Fletcher’s double jacket ted furnace, with plan of

burner of same ( Fletcher ) . . .27

27. Furnace for continuous gum work (White) . 28

28. Plaster model for metal work . . .30

29. Plaster model for vulcanite work . . 30

30 — 32. Hawes’ casting rings (White) . 36, 37

33. Mould for casting counter-die . . .41

34. Assay glasses (Mahins) . . .53

35. Dr. Black’s balance (Mahins) . . .59

36. Crucible for gold melting . . .62

37. Ingot mould stand . . . .63

38. Flatting mills (Ash) . . . .64

39. Metal gauge (Ash) . . . .65

40. Charcoal ingot mould . . . .66

42. Draw plate for wire making . . .67

43. Machine for making spiral springs (Robinson) . 68

44. Plate for single tooth in upper jaw . . 73

46. Hand shears ( White) . . . .75

47. Plate nippers (Ash) . . . .75

48. Plate benders ( White) . . . .75

49. Metal Punches ( White)’. . . .77

50. Pliers for band fitting (White) . . .79

51. Dr. Spalding’s standard clasp . . .80

52. Gold plate for partial lower . . .S3

55. Lateral suction chambers . . .86

LIST OP ILLUSTRATIONS XXV

FIG. PAGE

57. Central suction chambers . . .87

58. Dr. Kuna’s plate clamp ( Richardson ) . . 88

59. Cleveland’s suction chamber ( Richardson ) . 91

60. Gold plate for full lower . . .93

61. Articulation of plaster models (back) . . 95

62. Hawk’s-bill bite . . . .96

63 — 65. Extension bite . . . .97

66. American adjustable articulator (White) . . 99

67. English articulating frame (Ash) . . 100

68. Excising foi'ceps (White) . . . 126

69. Dividing saw (As7i) .... 126

70. Nerve extractor (Ash) .... 127

71. Drills for nerve cavities (Ash) . . . 128

75. Grinding lathe (Ash) .... 131

76. Punching pliers (Ash) .... 139

77. Gutta percha plate for vulcanite case . . 167

78. Spatulas for wax modelling (Ash) . . 169

79. Bell & Turner’s vulcanite flasks (Ash) . . 169

80. Vulcanite flasks (As7i) .... 170

81. Case sunk in lower part of flask . . . 171

82. Clamp for closing flasks (Ash) . . . 172

83. Hot- water plate for warming vulcanite (Ash) . 173

84. Case sunk in upper portion of flask . . 174

85. Hot-water tank and clamp combined . . 175

86. Ash’s vulcanizer (Ash) . . . .177

87. Whitney’s (American) vulcanizer (White) . . 178

88. 89. Hayes’ ironclad vulcanizer and automatic

lamp (White) .... 179 90. 91. Hoffstadt’s self-regulating vulcanizer (White) 180, 181

92. Rutterford’s “Single Screw vulcanizer ” (JEtutterford) 183

93. Files and riflers for vulcanite work ( White) . 185

94. Steel burrs for lathe head for vulcanite work (Ash) . 187

XXVI

LIST OF ILLUSTRATIONS

PIG. PAGE

95. Scorpers for finishing-up vulcanite work (Ash) . 188

96. Scrapers for ditto (Ash) . . . 190

97. Polishing lathe (Ash) .... 191 98 — 101. Strengthened attached to mineral teeth for

partial cases .... 192 102—6. Gold hands for partial dentures mounted in

vulcanite . . . . .194

107. Case sunk in flask for packing . . . 195

108, 109. Metal strengthener for vulcanite work . 197

110. Moulds for re-setting a vulcanite set . 200

111. White’s clamp and tank for the celluloid base . 209

112. Brushes for cleft palate cases . . . 216

113. Tweezers for ditto .... 219

114. Model of congenital cleft in palate . . 220

115. Metal mould for vulcanizing elastic velum . 222

116. Framework for closing metal mould . . 225

117. Congenital cleft, with artificial velum in situ . 227

118 — 20. Muscular closure of cleft . . . 230

121. Congenital cleft with velum in situ . 231

122, 123. Congenital cleft and artificial velum . . 233

124. Congenital cleft and velum in situ . . 234

125, 126. Hard and elastic portions of velum . . 235

127. Congenital cleft with edentulous jaw . . 237

128. Sectional view of deeply arched palate . . 238

129. Impression plate for taking divided moulds . 244

130. Hard rubber obturator for treating pei'foration of

131. Instrument for crushing masses of plaster in the

132. Model of mouth with fissure, and showing cicatrices

and old syphilitic scars . . . 254

133. Model of mouth showing loss of left half of superior

LTST OF ILLUSTRATIONS xxvn

Flw- PAGE

134. Instrument constructed to remedy defect . . 257

135. Instrument in situ .... 257

136. Spiral springs attached to set . . . 275

137. Spiral springs attached to set, showing their action

when opened . . . .275

138. Eye and pin of swivel united . . . 275

139. Eye and pin of swivel separated . . . 275

140. Mounted swivel for plate work . . . 275

Section I. The Preparation Of The Mouth For Artificial

TEETH.

Preparation of the mouth. — This is a practical point which involves very often the success or failure of any mechanical appliance introduced into the mouth for the sake of appearance or utility.

The most important thing connected with the matter is that the mouth should be in a thoroughly healthy and sound state. If the gums are edentulous they should be firm and insensible to slight irritation, and it is, above all things, important that there should be a normal condition of the salivary and mucous glands.

When there are still teeth standing, they should be carefully examined, any tartar attached to them carefully removed, and any cavities arising from decay properly filled.

Any tootli that cannot be restored to a perfectly sound and healthy condition should be extracted, including with these those teeth that from absorption of the root, or death of the periosteum, have become loose, although they may not at the same time be carious.

Stumps that are quite firm, give no pain on sharp percussion, and have no indication of inflammation connected with them around the adjacent gum, may be cut down level with the gum, and allowed to remain. The pulp cavities however, had better be opened up and plugged with gold, or such other material as may be indicated.

If a stump, on .the other hand, is loose ; or firm, but necrosed or carious, it must be extracted ; or, again, if the remains of a broken down tooth are quite firm, give no pain on touching, but slight pain on sharp percussion, and there is a line of red or purplish tint around the gum, then extract. Still, further, if a tooth locally gives no reason for supposing it to be unhealthy, but a gum-boil or scar is discovered near, it will be necessary to remove it.

On all these points no persuasion or direction on the part of the patient must be allowed to influence your own conviction and opinion. Firmness of will is on all account desirable under such circumstances, for submission to the wish of your patient not only involves much future vexation as a direct result, but also defers that which they regard as a great trial until a future time, when its results involve the entire readjustment of any artificial appliance that may have been fitted in, with the stumps and teeth intact.

The question how soon after extraction artificial teeth may be inserted, is one of great perplexity, unguided by practical experience. Theoretically, one would conclude that a considerable time should be allowed to elapse ; practically, from my own experience, I consider twenty-four hours enough, that is, I have many times taken out above ten teeth one day, and put in a full set of artificial teeth the next ; and in those cases where the shortest time has elapsed between the extraction and the replacement of teeth, I have found the least absorption, especially in comparatively young subjects.

Beyond the advantage of ready treatment which this offers, there is the still greater benefit of preserving more completely the contour of the face. Many practitioners consider that a temporary set may be fitted in at the end of a fortnight or three weeks, and a permanent set at the expiration of twelve or eighteen months.

I have found, however, that those cases that I have fitted in immediately after operating have fulfilled every requirement of a permanent set, so that no further change has been necessary.

After removing tartar or extracting teeth, the following preparation will be found very useful.

Eau de Cologne, §j ;

Aq. Rosas, gviij ;

As a wash for the mouth ; or Potass. Chloratis substituted for the Krameria, according to the condition of the patient.

This may be used every two hours as a mouth-wash the first day, and thrice daily afterwards, for a week.