|Year : 2014 | Volume
| Issue : 4 | Page : 235-240
A comparative study of pulse oximetry with the conventional pulp testing methods to assess vitality in immature and mature permanent maxillary incisors
Shini Susan Samuel, Abi M Thomas, Namita Singh
Department of Pedodontics and Preventive Dentistry, Christian Dental College, Ludhiana, Punjab, India
|Date of Web Publication||16-Oct-2014|
Shini Susan Samuel
Dental and Oral Surgery Department-II, Christian Medical College Hospital, Vellore - 632 004, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Context: Subjective pulp tests are not reliable, particularly in children. It is important for dentists to understand the various pulp testing methods that are available in order to make an accurate diagnosis of the state of dental pulp in children. Aims: To assess pulp vitality and compare the reliability of pulse oximetry with the conventional pulp tests (electric pulp test and cold test) in immature and mature permanent maxillary incisors. Subjects and Methods: Sixty selected children aged 7-18 years with normal permanent maxillary central and lateral incisors were categorized into Group I (mature teeth) and Group II (immature teeth). Thirty endodontically treated permanent maxillary incisors were used as the negative control. Statistical Analysis Used: The sensitivity, specificity, positive predictive value, and negative predictive value were calculated and the results were analyzed. Results: The specificity for the pulse oximetry test, cold test, and electric pulp test in Group I (mature teeth) was 100%. The specificity for the pulse oximetry and cold test in Group II was 100% and 80% for electric pulp test. Conclusions: For an accurate pulpal diagnosis in children, one should not rely on one pulp test alone. In young children, pulse oximetry method was found to be as accurate as cold test but large variations were seen in electric pulp test.
Keywords: Cold test, electric pulp test, mature and immature teeth, pulse oximetry, pulp vitality
|How to cite this article:|
Samuel SS, Thomas AM, Singh N. A comparative study of pulse oximetry with the conventional pulp testing methods to assess vitality in immature and mature permanent maxillary incisors. CHRISMED J Health Res 2014;1:235-40
|How to cite this URL:|
Samuel SS, Thomas AM, Singh N. A comparative study of pulse oximetry with the conventional pulp testing methods to assess vitality in immature and mature permanent maxillary incisors. CHRISMED J Health Res [serial online] 2014 [cited 2017 Apr 27];1:235-40. Available from: http://www.cjhr.org/text.asp?2014/1/4/235/142985
| Introduction|| |
The complex anatomical structure and inaccessibility of the dental pulp to clinical tests makes an accurate diagnosis of the health of the dental pulp often difficult and challenging to the dentist. The physical confinement of the dental pulp, with its rich sensory nerve innervations and microcirculatory components make the dental pulp a unique tissue.  Conventional pulp tests such as electric pulp tests and thermal tests measure the neural component of the pulp and are now considered as pulp sensibility tests.  Studies have shown that blood circulation, and not the nerve innervation, is the accurate determinant of the pulp vitality as it provides an objective differentiation between vital and non-vital pulp. , Hence, pulpal circulation is the true determinant of pulp vitality. The nerve fibers of the pulp may be resistant to necrosis than the vascular tissue and may be reactive long after the surrounding tissues have degenerated. , The conventional tests are subjective and depend upon the patient's perceived response to the stimulus as well as the dentist's interpretation of that response.
Dentists further face a more complicated situation because of the physiologic variations in the developing teeth and the emotional and cognitive development of a child as well. Sometimes, pain is used as a parameter for evaluation of tooth vitality and a pre-existing anxiety about the teeth can often lead to possible misdiagnosis. 
Numerous studies have been conducted to detect pulp blood components or pulp blood flow using different optical diagnostic methods such as laser Doppler flowmetry,  dual wavelength spectrophotometry,  pulse oximetry,  and transmitted light photoplethysmography.  Pulse oximetry methods has been reviewed as a diagnostic tool of pulpal vitality in the past. ,, It has been found to be more promising as it is non-invasive, objective, and painless test that directly measures the blood oxygen saturation levels. It is affordable and easily available for an average dental clinic.
Currently, there is no reliable and acceptable pulp testing method for the pediatric age-group. This could be due to the variations of the nerve fibers in the deciduous and immature teeth as well as the apprehension of a child to such procedure. Therefore, the object of this study was to assess and compare the various pulp testing methods (pulse oximetry, cold test, and electric pulp test) in permanent mature and the immature maxillary incisor teeth.
| Subjects and Methods|| |
The sample group consisted of permanent maxillary central and lateral incisors of subjects aged 7-18 years. The permission of the Ethical and Research Committee of the institution and written consent from the parents and subjects were obtained prior to the study. The sample selection and the pulp tests were carried out by the same clinician.
The selection criteria included the permanent maxillary central and lateral incisors to be free of any dental pathology (caries, restoration, developmental defects, or mobility)] with no previous history of any dental injuries. Any apprehensive patient or anyone with crowded permanent maxillary anterior teeth was excluded.
Sixty subjects who fulfilled the criteria were divided into Group I (mature teeth) and Group II (immature teeth)-30 subjects and both permanent maxillary central and lateral incisor teeth included (120 teeth) in the test. The root development of the maxillary incisors of Group II (immature teeth) were assessed using a single E-speed intraoral X-ray film and the root development was staged as described by Moorrees, Fanning, and Hunt. 
For negative control group, 30 endodontically treated permanent maxillary incisor teeth were used. The order of pulp testing was pulse oximetry test followed by cold test and electric pulp test. Pantera EA et al. found that the response to electric pulp testing is not adversely affected by the use of dichlorodifluoromethane. 
The pulse oximetry equipment (General Electric, Dash-2000) consists of a monitor, which gives the digital display of oxygen saturation values and is connected to a probe. The oxygen saturation level in the blood is measured by finger, foot, or ear probes. The systemic oxygen saturation (SaO 2 ) of the left index finger was measured first using a finger probe, and this served as the control for the SaO 2 values measured on the teeth.
The requirements of pulse oximeter used in pulp vitality test included:
- The sensors should confirm to the size, shape, and anatomical contours of teeth to prevent false readings from the distortion of the beam as it passes through a convex surface
- The light emitting diode sensor (labial surface) is received by photoreceptor sensor (palatal) which should be parallel to each other
- The probe should be held firmly onto the tooth surface to ensure accurate readings. 
For this study, an ear probe (supplied by Hygeia Medical Devices) was modified according to the anatomical morphology of permanent incisors to access the oxygen saturation of the tooth [Figure 1]. The size of the sensor was 5 × 5 mm and cylindrical rubber light-isolated shields were placed to accommodate the scatter to the convex interface. This also ensured the accurate adaptation of the sensor onto the tooth being assessed.  The values were recorded after 30 seconds of monitoring each tooth [Figure 2]. 
|Figure 1: Modified pulse oximeter ear probe placed on left maxillary central incisor|
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|Figure 2: Oxygen saturation reading with plethysmograph obtained from maxillary central incisor|
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Pulpofluorane refrigerant spray (Septodont Company) was used for the cold test. Each subject was instructed to raise his/her hand when they felt any sensation in the tooth. The teeth were isolated using cotton roll and air dried. Cotton pellet was saturated with pulpofluorane which was directly sprayed for few seconds from a distance of 5 mm. This was placed on the middle third of the labial surface of the teeth to be tested [Figure 3]. The responsiveness to the cold test was scored as "positive" (response within 15 seconds) or "negative" (no response within 15 seconds)  and was repeated on all four incisors.
|Figure 3: Cotton pellet saturated with pulpofl uorane refrigerant spray placed on left maxillary central incisor|
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For the electric pulp test, a monopolar pulp tester (Gentle Pulse TM , Parkell Electronics Division) was used. Gloves were not worn during the test and the teeth to be tested were dried and isolated to avoid any factors that could give false negative reading.  The patient was instructed to raise hand when he/she first perceived a tingling sensation in the teeth. A water-based toothpaste was used as the conduction media  and the electrode was placed on the incisal third of the teeth [Figure 4].  The intensity of the electric current was slowly increased to one numerical increase per five seconds till a response was obtained. The responsiveness to the electrometric test at any level of the tester was scored as "positive" and "negative". A second reading was recorded, with a recovery period of 2 minutes to eliminate the phenomenon of nerve accommodation.
|Figure 4: Electric pulp tester probe placed on left maxillary central incisor|
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Based on the number of true positive (TP), false positive (FP), true negative (TN), and false negative (FN), results were analyzed for each test in both groups. The sensitivity, specificity, positive predictive value, and negative predictive value were then calculated.
| Results|| |
The mean oxygen saturation of finger for Group I was 97.17% (standard deviation, SD = 0.58) and Group II was 97.2% (SD = 0.61).
In Group I (mature teeth), the mean SaO 2 values for maxillary right and left lateral incisors were 80.06% (SD = 0.86) and 80.06% (SD = 1.08), respectively; the mean SaO 2 values for maxillary right and left central incisors were 81.1% (SD = 0.80) and 81.36% (SD = 0.99), respectively.
In Group II (immature teeth), the mean SaO 2 values for maxillary right and left lateral incisors were 81.66% (SD = 1.58) and 81.36% (SD = 1.2), respectively; the mean SaO 2 values for maxillary right and left central incisors were 83.93% (SD = 0.73) and 84.2% (SD = 0.6), respectively. The pulse oximetry test recorded SaO 2 readings from all the maxillary incisors in both Group I (mature) and Group II (immature), but were also recorded from three endodontically treated teeth (negative control).
The cold test elicited positive response from all the maxillary incisors in both Group I (mature) and Group II (immature), but two of the endodontically treated teeth gave false positive response.
The electric pulp test elicited positive response from all 120 mature maxillary incisors in Group I, whereas only 96 immature maxillary incisors in Group II gave positive readings. One of the endontically treated teeth (negative control) gave a false positive response.
The sensitivity, specificity, positive predictive value, and negative predictive value were calculated for each test method [Table 1] and [Table 2].
|Table 1: Comparison of sensitivity, specificity, positive predictive value, and negative predictive value in Group I (positive predictive value, negative predictive value)|
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|Table 2: Comparison of sensitivity, specificity, positive predictive value, and negative predictive value in Group II (positive predictive value, negative predictive value)|
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Sensitivity = the ability of a test to identify teeth that are really diseased (endodontically treated teeth) and was calculated according to the formula TP/(TP + FN).
Specificity = the ability of a test to identify teeth without disease and was calculated according to the formula TN/(TN + FP).
Positive predictive value = the probability that a positive test result really represents a diseased tooth and was calculated using the formula TP/(TP + FP).
Negative predictive value = the probability that a tooth with a negative test result is free from disease and was calculated using the formula TN/(TN + FN).
| Discussion|| |
Chambers has suggested that the ideal technique for evaluation of dental pulp status must be non-invasive, objective, painless, inexpensive, reliable, reproducible, standardized, and easily completed.  The only indicator of dental pulp status that fits most of the above criteria is the periapical radiograph, a late indicator of vascular integrity.  Neural stimulation methods measure the neural component of the pulp, thereby indirectly monitoring pulp vitality is also a late indicator of pulpal necrosis. 
Pulse oximeter is a non-invasive oxygen saturation monitoring device widely used for recording blood oxygen saturation levels. Goho C assessed pulpal vascular oxygen saturation using a modified pulse oximeter ear probe in primary and immature permanent teeth.  Radhakrishnan S et al. investigated both electrical and pulse oximetry vitality tests in normal maxillary incisors and found negative correlation between the SaO 2 readings and electrical testing readings. 
In the present study, the SaO 2 for both mature and immature permanent maxillary incisors (80-82%) were found lower than the SaO 2 values recorded on the patient's finger (97.2%). According to Gopikrishna et al., the normal oxygen saturation values for human permanent teeth were in the range of 75-85%.  This may be due to the limitations of using a probe designed for other body parts as well as the diffraction of infrared light by enamel prisms and dentin.  Fein et al. suggested that lower SaO2 values for pulpal circulation may also be attributed to light ray scatter through the gingiva. 
Consistent positive responses were elicited in all maxillary incisors by pulse oximetry method, cold test in both mature and immature group. Although consistent positive responses were elicited with electric pulp test in Group I (mature teeth), a large variation in the readings were noted in Group II (immature teeth).
Electric pulp test on immature permanent teeth (open apex) is often unreliable because the myelinated nerve fibers entering the tooth may not reach their maximum number until the apex of the tooth is near completion, or later in many cases. It may also be due to lack of development of the plexus of Raschkow at the pulp dentin border. Complete development of this nerve plexus often does not occur until the final stages of root formation. 
The sensitivity for the pulse oximetry in both mature and immature teeth was 90%. One of the limitations of pulse oximetry is motion artefact, and could be the reason for the false positive response in endodontically treated teeth in this study. It could also be due to the limitation of using a probe designed for other body parts, and not specifically for the anatomy of the tooth.
The sensitivity for the cold test and electric pulp test was 93% and 96% respectively. The false positive responses in endodontically treated teeth to cold and electric pulp test were obtained from the same patient. Jones VR et al. reported false positive response to cold in two endodontically treated teeth and suggested that the cold was transferred to gingival or to adjacent teeth through cast crown restoration.  There were no cast crowns on these teeth in this study, and hence the false positive readings for both these tests could be due to patient anxiety.
In Group I (mature teeth), the specificity of the pulse oximetry method, cold test, and the electric pulp test was 100%. In Group II (immature), the specificity of pulse oximetry method and cold test was found to be 100%, but 80% for the electric pulp test. Brandt K in a longitudinal study of electrometric sensitivity found an increase in sensitivity with large variations from child to child and even in the same child.  Moorrees et al. suggested that the largest variations between individuals were found when the root was in the early stages of development. 
In this study, pulse oximetry was found to be as accurate as cold test and electric pulp test in permanent mature maxillary incisors although electric pulp test showed varying results in immature teeth.
| Conclusion|| |
For an accurate pulpal diagnosis, one should not rely on a single test; rather it is recommended to assess with at least two reliable tests. With pulse oximeter, it is important that one should not just interpret the oxygen saturation reading but need to obtain a consistent plethysmograph. Use of pulse oximetry in its current form is questionable in partially erupted and malposed tooth.
Among the three tests, cold test was found to be a simple procedure which can yield valuable information about the state of the pulp without any expensive equipment.
The wide variations of sensitivity to electric pulp test in the immature teeth could be due to psychological, technical, and biologic factors and these factors should be taken into consideration while using electric pulp test among the pediatric population.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2]