1084 Orthodontic Abstracts and Reviews

The appearance of the bone in conditions in which the central incisors arepermanently separated reveals a solid block of cancellous bone covering thealveolar crest either completely (VI), or showing a V-shaped gap in the crest(VII) . The crests do not come to a point but have square ends.

E. N.

Drinking Water and Teeth. By Eric C. Erskine Williams, British DentalJournal 60: NO.4.

Drinking water should be free from taste, color, odor, without obvioussuspensions, lacking contaminations, and have a certain quantity and qualityof mineral contents. An excessive amount of mineral contents is responsible fordiseases of the stomach, intestines, kidneys, and for the formation of salivarycalculus. Deficiency in mineral salts promotes goiter, rickets, etc.

Clinical observations demonstrate the relationship between hardness ofthe local water (containing magnesium and calcium carbonates and chlorides)and native teeth.

In areas with a substrata of chalk and in villages with hard water impreg­nated with salt, the permanent teeth of the population are unusually good.They are well formed, strong, brittle, lustrous, and of yellow-white hue. Thealveolar bone is dense and compact. The teeth possess a high immunity to decay,which is usually confined to one surface, narrow seamed and deeply penetrating.

In districts with soft water the structure of the teeth is adversely affected,as soft water is most times deficient in organic materials. The crowns are milkwhite in color, oyster shell in texture, smooth, and the jaw bones are morecancellous; movement of teeth in orthodontic treatment is accomplished withgreater rapidity; they have inferior resistence to dental caries.

Hard water is found in the waters of South England where enormousquantities of chalk exist, in the hills of South Downs, the Chilterns, and London(where the hardness ratio of the water is 25), and in the Home Counties whereeven extreme deposits are found in cooking utensils, etc. On the other hand,Douglas, the Isle of Man, Liverpool, etc., receive soft lake water; Chester takesits water from Lake Bala (with a hardness rate of only one half of Londonwater); and in many country hamlets the water supply is collected from rainwater.

E.N.

Impacted Wisdom Tooth Causing Reflex Irritation of the Lungs. By W. L.Balendra, British Dental Journal 60: No.7.

The patient, a woman aged thirty-two years, gave a history of asthma. Atthe age of twenty-two years, she suffered the first attack, which lasted eightmonths. This attack followed a chill; it subsided with medical treatment. Tenyears later the asthma recurred following chickenpox. It took the form ofspasms lasting about three minutes, more frequent at nights. The spasmstarted with a scratchy feeling in the throat, but there was no pain in theregion of the third molars. Medical treatment for over one year and cauteriza­tion of the tonsils did not improve the condition.