Document Sample

Tooth Eruption

Nonhuman primate infants.

Time of Test
Whenever convenient (good to do it while another task is being done on the animal).

Daily from birth until eruption of all five baby teeth on both sides in upper and lower jaw.

Examine each animal for the eruption of teeth through the gum. When the tooth has cut
through the gum, record the date on the daily tooth check sheet (form 7 in Appendix).

Definitions of teeth are as follows:

   A—central incisors
   B—lateral incisors
   D—first molar
   E—second molar

The teeth usually erupt in that order. However, in some
individuals, especially in long-tailed macaques, the first
molars erupt before the canines.

Additional Protocol to Determine Degree of Eruption

1. Check every day for new monkeys in the nursery. If a new infant has arrived, start a
   new data sheet for it (form 8 in Appendix). Fill in the information at the top right-
   hand corner and write the day's date in the space on the left, with "f.c." (first check).
   If the incisors have already erupted, follow instruction #3 below. Follow the date with
   a "-?" because you don't know how many days ago the tooth erupted.

2. When a tooth is first observed to reach a certain stage, place the day's date for that
   tooth on the data sheet.

Physical Development

3. If a tooth has passed a stage by the time you see it, write in today's date for the highest
   stage it has reached and add a note of the number of days missed since the last time
   this tooth was observed. For example: A canine was at Stage 1 the last time you saw
   it, but you missed a week and the next time you saw it, it was already at Stage 3. Put
   a dash for the date of the stage you missed (Stage 2). For Stage 3, put the date of
   actual observation and write next to it "-7" for the missing week.

Use the following descriptions to determine the three stages of eruption in infant

Stage 1

Incisors, canines, and molars (Fig. 1):

If you observe any of the following in the location where the tooth you are observing is
due to erupt, the tooth has reached Stage 1:

• Elevated ridge or swelling
• Redness, and sometimes bleeding if rubbed

                                      Fig. 1—Stage 1

Stage 2

If you observe any of the following in the location where the tooth you are observing has
erupted, the tooth has reached Stage 2:

Incisors (Fig. 2):
• The tooth is visible—i.e., it has broken
   through the gum but the entire top surface
   of the crown is not yet through.

                                                         Fig. 2—Stage 2 incisors

Physical Development

Canines (Fig. 3):

• The tooth is visible—i.e., has broken
  through the gum, but has not yet reached
  Stage 3.

• There is a little white dot in the location
  where the cusp is about to break

• The tooth is not yet visible, but you can
  feel a sharp edge in the location where
  you expect the tooth to erupt.

                                                    Fig. 3—Stage 2 canines

Molars (Fig. 4):

• The tooth is visible, but only one or two
  cusps are showing.

• A little white dot is visible in the location
  where the first cusp is about to break

• The tooth is not visible, but you can feel a
  sharp edge in the location where the tooth is
  expected to erupt.

                                                    Fig. 4—Stage 2 molars

Physical Development

Stage 3

If you observe the following, the tooth has reached Stage 3:

Incisors (Fig. 5):

• The entire top surface of the crown has just
  emerged. (If more than just the top of the
  crown has emerged, it is beyond Stage 3.)

                                                       Fig. 5—Stage 3 incisors

Canines (Fig. 6):

• The cusp of the canine is level with the adjacent
  lateral incisor.

                                                        Fig. 6—Stage 3 canines

Molars (Fig. 7):
• All four cusps have erupted and the entire top
  surface of the crown has just emerged. (If more
  than just the top surface of the crown has
  emerged, it is beyond Stage 3.)

                                                        Fig. 7—Stage 3 molars

Physical Development

Anthropometrics and Radiographs

Anthropometric measurements of Macaca nemestrina infants are made at regular intervals
up to a postconception age of 355 days. X-rays are taken to determine the degree of
ossification of the epiphyses and round bones of the left hand and foot as a measurement
of development.

Animals are assessed at birth and at 173, 187, 215, 245, 271, 299, and 355 days
postconception; a ±2-day margin is acceptable.               Consult the calendar in the
"Anthropometrics" folder to see which animals are schedule to be measured and
radiographed. On the anthropometric and ossification data sheets (Appendix, forms 9-
11), fill in the date and the animal's age. If assessment is being done early or late, note the
scheduled date and the animal's age.

Calipers, sliding scale (Fig. 1), scissors, tailor's tape (1/2 inch width), head circumference
measuring tape (Fig. 2), x-ray film, lead gloves, x-ray viewing machine, magnifying glass,
and anthropometric and ossification data sheets.

Each measurement is made by two persons. Do not disclose individual measurements
until both have been taken. Interobserver measurements that vary by more than 3% must
be repeated. Measure head circumference, length, and width to the nearest millimeter;
measure foot length and crown-rump length to the nearest tenth of a millimeter. Record
the two scores and their average on the data sheet. If the average is not an integral
number, round up at > 0.5 (e.g., 233.5 becomes 234).

HEAD CIRCUMFERENCE: Measuring tape should encircle the head below the brow ridge
(covering the animal's eyes), along the nuchal crest above the ears, and should cover the
occiput. Pull the tape tightly through the clamp and then fasten clamp at the side of the
head. Read the measurement while the tape is on the animal's head.

HEAD LENGTH (Fig. 3). With the spreading calipers, measure the length from the area
between the eyes to the occiput. If the animal is disturbed by the procedure, blindfold it
with tailor's tape. Read the measurement while the calipers are in place.

HEAD WIDTH (Fig. 4). With the spreading calipers, measure between the two widest
points of the skull; the landmarks are just above and in front of the ears. Feel for these
points first and then replace your fingers with the calipers.

Physical Development

LEFT FOOT LENGTH (Fig. 5). Place the monkey's heel flush with the base of the sliding
scale. Center the foot directly over the scale, with toes aligned and completely extended.
Read the length from the end of the longest toe, excluding the nail. For accuracy in
reading, you must be positioned directly over the scale.

CROWN-RUMP LENGTH. If the animal is wrapped in a diaper, move the diaper away from
the dorsal surface so that it does not come between the animal and the sliding scale.
Allow the animal to clutch the diaper ventrally as this procedure is usually stressful. Place
the animal on the scale in a supine position with its rump against the base of the scale and
its tail to the side. Hold the animal's feet and lift its legs to facilitate positioning of the
rump. Apply pressure to the ventral trunk so that the animal does not arch its spine. Hold
the head steady in the Frankfurt plane (see Fig. 4). Bring the sliding mechanism down to
the crown. Holding the sliding mechanism firmly in place, lift the animal away from the
scale and read the value while positioned directly above the scale.

WEIGHT. Put the infant in the weighing bowl on the scale. Allow it to clutch a diaper for
security. To adjust for the weight of the diaper, place a separate diaper in the weighing
bowl and push "Tare" button. Remove the diaper and place the animal with the security
diaper in the bowl. As animals rarely remain stationary during this procedure, estimate the
weight as that figure which appears most consistently on the digital display. Check this
weight against that taken daily by the technicians in the Infant Lab.

Fig. 1—Sliding scale                                   Fig. 2—Head circumference
                                                       measuring tape

                    Fig. 3—Head length

Physical Development

Fig. 4—Head width (Frankfurt plane)
                                                                    Fig. 5—Measuring foot

Radiographs of the animal's left hand and arm and left foot and lower leg are to be
performed at the time of each anthropometric assessment. Take the animal to the x-ray
suite in a clean transport cooler. Be certain that the locking mechanism is working.
Coolers without the "Live Animal" label are preferable because they attract less attention
in the hallways. Notify lab office personnel which animals are being taken to x-ray. Bring
the animal's anthropometric data sheets, extra diapers, several pairs of surgical gloves, and
x-ray film. Use Kodak Diagnostic Film, X-OMAT AR, 50/35 x 43 cm (cat. #165 1678).
One sheet of film is sufficient for two animals, but bring extra sheets in case x-rays need to
be redone.

LOADING FILM. In the darkroom, turn on the developer and close the lid. Lock the door,
turn off the main light, and turn on the infra-red light. Remove film from the envelope,
taking care to separate film from paper sheets. Do not discard envelope. Insert film in the
cassette and place the cassette in the door marked "unexposed," which is connected to the
x-ray room.

TAKING X-RAYS. The x-ray machine should be set at 200 milliamperes, 1/30 seconds,
42 peak kilovolts. The light source should be placed one meter above the cassette; check
this distance at each radiography session. Place the cassette on the x-ray table and cover
half of the cassette with lead shields.

Physical Development

Place the animal on a folded diaper at the edge
of the cassette and cover its body with lead gloves.
Extend the animal's left leg out onto the cassette. Use
gauze tape around the knee and elbow joints before taping
the limbs to decrease discomfort to the animal. Tape the
left leg down at the knee joint and the foot. Extend the
left foot as far as possible and hold the hallux at a 90°
angle away from the toes. Such placement decreases the
amount of superpositioning of the tibia and fibula, thereby
maximizing the clarity of the areas of interest. Tape the
left arm down at the elbow joint. See that the fingers of
the left hand are aligned, flattened, and taped with the
pollex set off from the other digits. See Fig. 6 for proper
                                                               Fig. 6—Placement for x-ray

When finished, replace the animal in the cooler and clean the cassette, table and lead
gloves with disinfectant. Cover the exposed side with lead shields and use the unexposed
side to x-ray the next animal. Place the exposed cassette in the door marked "exposed."

DEVELOPING FILM. With the door locked and infra-red light on, remove the film from the
cassette and feed it into the x-ray machine. Wait for the second safety light to appear
before turning on the overhead light. X-rays take approximately 3-4 minutes to develop.
Check the developed x-rays for clarity and detail (i.e., lack of superpositioning, clarity of
carpals and tarsals). Return the x-ray to the original envelope for transport. When you
are finished, be certain that both the x-ray machine and developer are turned OFF.

CONCLUDING STEPS. (1) Return the animals to their cages in the nursery or quad room.
(2) Disinfect the coolers. (3) Return the data sheets to the folder and cross off the animal
numbers on the calendar.

READING RADIOGRAPHS. The radiographs reveal the state of ossification for the
epiphyses of the metacarpals, metatarsals, and phalanges, the carpals and tarsals, and the
distal epiphyses of the ulna, radius, fibula, and tibia. To read the radiographs, you will
need a magnifying glass, an x-ray viewing machine, hand and foot ossification data sheets,
and diagrams of the bones in the hand and foot (Fig.7).

There are three possible ossification scores
for the epiphyses and round bones:

• Absent (score 0.0)—There is no visible bone present.
• Initial (score 1.0)—Beginning ossification of the bone is barely visible. This is the most
  difficult stage to identify because it appears as a smudge on the x-ray. It looks like a
  small, cloudy white spot with no definition around the edges.

Physical Development

• Present (score 2.0)—Ossification of the bone is clearly visible. The bone may be small,
  but it has a definite shape and sharper white appearance than the initial stage of

Two scores for each hand and foot are tallied and entered into the Bone Data File. The
foot score (fs) and hand score (hs) are computed by adding the total score from the
ossification data sheet. The foot number (fn) and hand number (hn) are the actual number
of centers present (i.e., any center with the score 1 or 2).

              Fig.7—Ossification centers of hand (above) and foot (below)

Physical Development


Newell-Morris, L., Tarrant, L.H., Fahrenbruch, C., Burbacher, T.M., and Sackett, G.P.
Ossification in the hand and foot of the pigtail macaque. II. Order of appearance of
centers and variability in sequence. Am. J. Phys. Anthrop. 53:423-439, 1980.

Newell-Morris, L., Carrol, B., Covey, A., Medley, S., and Sackett, G.P. Postnatal growth
and skeletal maturation of experimental preterm macaques (Macaca nemestrina). J. Med.
Primatol. 20:17-22, 1991.