i8o DENTISTRY 



encouraging progress is being made toward their ultimate solution. Incidentally the 

 resources of dental art are being enlarged in all departments, with a corresponding 

 improvement in operative and restorative procedures. 



Notable advances have been made in the control of pain in the performance of 

 dental operations by the intelligent use of both local and general anaesthesia, so com- 

 plete a success having been achieved that there is no longer any proper justification 

 for the obligatory infliction of pain in the performance of any dental operation. The 

 scientific study of the physiological action and therapeutic application of the large 

 number of local anaesthetic drugs now available, and the improved methods of tech- 

 nique devised for their rational use by numerous investigators, notably by Prof. Guido 

 Fisher, Prof. Hermann Prinz and others, has made it possible to use them safely for anaes- 

 thetising any predetermined area about the mouth and jaws, while the element of 

 danger from toxic effects has been practically eliminated. Moreover it is now possible 

 to maintain for an indefinite length of time a preliminary or peripheral stage of general 

 anaesthesia, in which the sensory nerve terminals are anaesthetized while consciousness 

 is in no appreciable degree interfered with, or to produce a state of " analgesia " (the 

 elimination of pain) by carefully graded administration by inhalation of a determinate 

 mixture of nitrous oxide and. oxygen. The patient breathes the requisite amount 

 of mixed gases through a speciallyscontrived inhaler through the nostrils until the analgesic 

 state is produced, leaving the mouth unobstructed for the required operation, which 

 is performed without sensation of the slightest pain by the patient, yet without dis- 

 turbance of general consciousness. The administration of the mixed gases for the 

 production of the analgesic stage of anaesthesia may be continued without danger 

 throughout the operation. 



Notable advances have been made in the study of the nervous relations of the 

 teeth and their relations to disturbance of reflex character in other parts of the body. 

 Many stubborn and severe neuralgias about the head and neck, some of the choreas 

 of childhood, epilepsy, dementia praecox, lesions of the ocular muscles, tic douloureux, 

 arrested development of the jaws, of the nasal chamber and facial region, have in a 

 variety of instances been found to have their origin in malpositions, impeded eruption 

 or impaction of certain of the teeth, prompt relief of the disorders having followed 

 the removal of the source of their dental origin. 



The group of inflammatory disorders that disastrously affect the supporting and 

 retentive tissues of the teeth, referred to as gingivitis, phagedenic pericementitis, 

 pyorrhea alveolaris, etc. or commonly referred to as "Rigg's disease," have been the 

 subject of close and careful study for many years, but the application of modern 

 methods and the advances made in bacteriological science have done much to clear 

 up their pathological nature. Among the important results thus attained is the knowl- 

 edge that the destructive process is not a single disorder with a specific bacterial organ- 

 ism as its exciter, but a mixed infection giving rise to a group of inflammatory pro- 

 cesses having a variety of expressions, due to differences in the nature of the infecting 

 organisms concerned in their production, and to differences as well in the character 

 of the tissues which are the seat of the disorder. Two broadly distinguished classes 

 of disorders are now recognised as leading to the loss of the teeth by destructive in- 

 flammation of their supporting tissues. First, those which are primarily due to the 

 accumulation of tartar of salivary origin upon the exposed tooth surfaces, which 

 deposits impinge upon the gum margins about the necks of the teeth, act as a mechanical 

 irritant to the soft tissues, thus rendering it susceptible to infection by pus-producing 

 bacteria, and, second, the class of infections of the alveolar tissues which occur in con- 

 nection with a weakened condition of the body due to malnutrition in some of its 

 many forms, in which there is a general lowering of resistance to bacterial invasion, 

 the gum tissues because of their relatively low resistance being in these cases the select- 

 ed point of entry for the disease-producing germs commonly found in the mouth cavity. 

 The better understanding of the causation of these gingival and alveolar inflammations 

 has made possible their more rational, and, therefore, their more successful treatment. 



