oriented occlusal plane interferes with denture stability and retention, in addition to more vital functions of the

teeth and oral cavity. This study used a photographic approach to determine the occlusal plane inclination in

relation to some anatomical references. 95 young volunteers of Mahsa University College, aged between 20

and 25 years, were selected for this study. The participants were selected according to specific inclusion

criteria. A standardized digital profile and front images were taken for each participant using a digital camera

that is fixed on a tripod with the fox bite plane placed on the occlusal surfaces of the maxillary teeth. The angle

amplitude of the reference planes in relation to the occlusal plane was measured using a digital protractor on the

screen display. The results revealed that the least mean angle difference was with the AT1, while higher

variability was found using the Frankfort plane. In addition, there were no significant differences between the

two genders or among the three ethnic groups. It is concluded that the photographic method can be used

1 Introduction

The occlusal plane is “an imaginary surface that is

related anatomically to the cranium and that

theoretically touches the incisal edges of the incisors

and the tips of the occluding surfaces of the

posterior teeth. It is not a plane in the true sense of

the word but represents the mean curvature of the

surface” [1]. The height of the lower canine, which

nearly lines up with the mouth commissure,

determines it anteriorly, as does the height of the

the margin of the bony canal on the skull. This plane

is used as a reference for most of the anatomical

parts of the skull. It orients the skull parallel to the

horizontal plane. It forms a variable angle with the

1; lower limit of tragus, 2; middle point of tragus, 3;

upper limit of tragus,T-A; ala-tragus or Camper line,

P-O; Frankfort plane or line.

1.1.2 Camper’s line

A line from the lower border of the ala of the nose

to the upper border of the tragus of the ear. The

camper line becomes a plane when the imaginary

lines connect the two alae of the nose anteriorly and

the tragus posteriorly. Approximately, it is parallel

occlusal plane should be parallel to the

interpupillary line. It should be 2mm below the

upper lip line or smile line [2]. This line is

indispensable to validating the parallelism between

the anterior tooth edges and the eyes (Fig. 2).

1.1.4 The curve of Spee

It is the antero-posterior curve line that extends

from the tip of the lower canine and follows the

buccal cusps of the mandibular posterior teeth

should be perpendicular to the long axis of occlusal

forces produced by an optimal cervical posture and

an optimized mandibular closing path [3].

The inclination of the occlusal plane (IOP) is one of

plane inclination during craniofacial growth relative

to various facio-cranial reference lines varied in

anterior rotation during growth. The most

significant changes in the occlusal plane inclination

were from the maxillary base, Frankfort horizontal,

and cranial base reference lines. Small but

It also influences the masticatory closing pattern in

the sagittal plane. Anterior convex closure patterns

dominate when the occlusal plane is inclined in the

anterior direction. In contrast, the majority of

posterior convex closure patterns were induced by

the posteriorly inclined occlusal plane. The

appearance of these types seemed to reflect a

harmonious relationship between the inclination of

the occlusal plane, tooth guidance, and other central

and peripheral controls. The correlation between the

depends on an adequate orientation of the occlusal

plane.

Aesthetics; anterior upper and lower mal-positioned

and phonetic elements. However, the occlusal

correction of maxillary natural teeth should be

always carried out carefully without altering the

patient’s aesthetics. On the other hand, it is often

easier to correct the incisal edge of mandibular teeth

[ 7 ].

and ‘v’ sounds. As well as facilitating interpersonal

communication, there is a social expectation that

phonetic patterns will be affected in a specific way.

Thus, the absence of anterior teeth (anterior part of

the occlusal plane) can affect self-image as well as

speech [3],[ 4].

Excessive lateral deviation around posterior teeth to

develop socially acceptable speech patterns will

require adaptation of the jaw neuromuscular system.

Exceeding the physiological ‘adaptability’ of one or

randomly, and the reference points were marked off

on the face and then photographed using a digital

camera fixed to a tripod. Profile and frontal photos

were taken while the subject was sitting in an

distance, magnification, level, and height of the

camera were fixed (Fig. 5, Fig. 6).

Lower border of the ala of the nose (A)

The reference planes and lines that were used in this

study are:

Frankfort plane (FP): from the upper border of the

tragus to the left orbitale

Table 1. The inter-examiner reliability of the 3

examiners for LAT1 records. P; Pearson correlation

The angles between some assigned reference planes

or lines were recorded on the computer monitor

using software (MB-Ruler), and on printed

photographs manually, and they were compared to

estimate the dependability by three examiners. The

results were linear, highly significant, and positive

(P = 0.995, DF = 28, at p<.001), Fig. 7.

Table 3. The records of the differences in angle

degrees between the occlusal plane and different

reference lines on the two sides of the face in males

G;gender, N;number, M.A; mean angle, P-val.; p-

value, RAT1-ROP; right lower ala tragus line-right

occlusal plane, RAT2-ROP; right middle ala-tragus

line-right occlusal plane, RAT3-ROP; right upper

ala-tragus line-right occlusal plane, ROP-FP; right

occlusal plane-Frankfort plane, LAT1-LOP; left

The differences between the records on the right and

left sides of the face were not significant at p<0.00

for the different ethnic groups (Table 4).

M; Malays, I; Indians, C; Chinese

records of the OP in relation to the reference lines

and plane is shown in Table 1. The least variable

record was OP to FP; hence, the Frankfort plane

may be considered the most reliable and least

variable reference when used to orient the occlusal

plane compared to the Camper line (Table 6).

mean record, SD; standard deviation, CV;

coefficient of variability

AT1; ala-tragus lower point, AT2; ala-tragus middle

point, AT3; ala-tragus upper point,OP-FP; occlusal

plane-Frankfort plane.

recording.The ala tragus line, or Camper line,

running between the lower border of the ala of the

high variability of CP disproves its use for occlusal

plane orientation in clinical situations that imply

more precise and less inconsistent errors.On the

plane and the occlusal plane was +10.2 degrees,

of OP. As a reference, the Frankfort plane offers the

least variability and more repeatability among the

studied references (Camper plane) at different

starting points; therefore, we support the use of the

Frankfort plane to study and record the occlusal

plane in any future research. The outcome of this

in daily practice, using the Frankfort plane as a

record.In the future, research work is proposed to

reveal the effect of changing the inclination of the

occlusal plane anterioposteriorly as well as laterally

on the teeth and bone supporting the artificial

replacement using the mathematical method.

References: