. The Dental cosmos. h. (Fig. 3, d-f-d.) This calculation was proportionate tothe teeth in each case. His calculationfor the position of the remaining teethwas based upon an average measurementgathered from many cases. This consti-tuted an error, which Dr. Hawley endeav-ored to correct by using average toothmeasurements and calculating the dentalarch from these averages—when the lat- eral and canine were not present. Haw-leys determination also depended uponthe accuracy in drawing a tangent, whichis difficult and open to considerable error. A new approximate arch. AdoptingBonwills calculation
. The Dental cosmos. h. (Fig. 3, d-f-d.) This calculation was proportionate tothe teeth in each case. His calculationfor the position of the remaining teethwas based upon an average measurementgathered from many cases. This consti-tuted an error, which Dr. Hawley endeav-ored to correct by using average toothmeasurements and calculating the dentalarch from these averages—when the lat- eral and canine were not present. Haw-leys determination also depended uponthe accuracy in drawing a tangent, whichis difficult and open to considerable error. A new approximate arch. AdoptingBonwills calculation of the anterior arcand drawing it (Fig. 3, d-f-d), I takesix times the mesio-distal diameter of theupper central incisor, f-j, using it as theradius of another circle, F-c-c, uponwhich the radius is then taken to marksix arcs, as in Bonwills circle arcs mark the points c c, which arethen connected to D D by lines D-c, D-c,iiIinii which the mesio-distal diameters ofbicuspids and molars are marked, giving. BARNES. DENTAL IMPACTION AND PREVENTIVE TREATMENT. 9 the lateral width limits of the dentalarch, d d and x x. This furnishes a ma-thematical calculation of a coronal align-ment arch proportionate to the teeth, andis the smallest arch into which the teethcan erupt easily and without lateral con-tact until occlusion. Broad or narrowteeth will furnish proportionately broador narrow arches. Actual tests of arches Fig.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectdentist, bookyear1912
