Nance mills hamilton model analysis
Nance , Mills
Published on: Mar 3, 2016
Transcripts - Nance mills hamilton model analysis
Department of Orthodontics
(1893 - 1964)
• Born on August 14, 1893 in Jackson , Tennesse.
• He was the Youngest of the five children.
• Upon the death of his mother in 1908 he
attented the famed Webb School in Bell Buckle ,
• While working in a copper mine in Miami , he
suffered a fall resulting in several fractures and
spinal injury . After a long convalescence during
which he was obliged to wear a steel brace, he
made a complete recovery.
• Following his marriage , he decided to enter the
profession of dentistry and graduated from the
North Western University in 1919.
• After practicing briefly in Arizona, he moved to
Denver where he opened his own office
• In 1928 he moved to LA, practising for a number
of years before moving to Pasadena where he
remained until a Heart attack forced his
retirement in 1948
• He is best known for his paper entitled
“Limitation of Orthodontic Treatment” , which
appeared in April, 1947.
• The Orthodontic Specialty, in recognition of
Hay‟s services over the years, conferred upon
him Albert H. Ketcham Memorial Award in 1963.
• It was a fitting climax to Dr. Nance career, before
he passed away due to heart attack at his home
in Pasadena , California, 1964.
• For patients with malalignment of teeth resulting
from lack of space, it is important to determine from
the study casts the amount of crowding in the
maxillary and the mandibular arch.
• For this two measurements are required in each
a) calculation of space required
b) calculation of space available
MATERIALS REQUIRED :
• Sharp Divider
• Brass wire 0.010 inch in diameter
• Study Models
• A ruled 3 x 5 inch card for recording
STEPS ARE AS FOLLOWS
• Recording the mesio-distal width of each tooth
mesial to the first permanent molar using the
divider. Sum total corresponds to the necessary
space required.(Ideal Arch Length)
• Recording the actual arch length using a soft
wire. This is contoured to the individual arch
shape and placed on the occlusal surfaces over
the contact points of the posterior teeth and the
incisal edges of the anteriors
• The assessment of space relationship is the
result of the difference between the ideal and
actual arch length.
Negative Value shows “space deficiency”.
Positive Value shows “space excess”.
• It was put forward by Loren F. Mills and Peggy M.
Hamilton in 1965.
• They devized a mathematical method for computing
the arch perimeter by means of arch width and
length measurement, after a study done on over
500 maxillary stone casts, obtained from the US
Naval Academy, Annapolis, Maryland. Of this 362
casts were selected with a full complement of
permanent teeth mesial to the first permanent
• This technique is best suited for the following :
a) Population studies contrasting the size and
shape of the jaws with effects of such variables, as
ancestery, race, nutrtion, climate, or other
b) Malocclusion studies which estimate the
space available for teeth and the effects of faulty
mouth habits on jaw size.
They related the maxillary outline form with that of
a parabola. Other recognised forms, such as
square and „V‟ shape , are present but do not
occur too frequently in the general population
• The advantages of a mathematical parabola are
as follows :
a) All are essentially alike
b) By a proper choice of scales and axes any
parabola can be made to coincide with any other.
• They gave the formula to calculate the
ARCH PERIMETER as :
Where, x = arch length
y = intermolar arch width
MEASUREMENT OF ARCH WIDTH
A Korkhaus # 14 three
calliper is used to
measure the arch width ,
from a pencil inscribed
point at the gingivo-incisal
margin of first molar at a
point bisected by a line
formed by the buccal
MEASUREMENT OF ARCH LENGTH
• It is obtained by measuring the distance from a
line joining the midpoint of a line drawn from the
distal surfaces of first molars to the interdental
pappila of the central incisors
• Mill‟s and Hamilton‟s study compared this type of
arch perimeter calculation with measured
orthodontic archwire, the results showed
measured wire technique had “six times”
greater error than the mathematical method.
• The main advantage of this method of arch
perimeter measurement is that it is far less time
consuming than direct measurement.