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Intraoral humidity during operative procedures
J. Dent. 1994;
fa
22: 89-91
Intraoral humidity procedures
during operative
P. J. M. M. Plasmans, N. H. J. Creugers, R. J. Herm.sen* and M. M. A. Vrijhoef* TRIKON: Institute for Dental Clinical Research, University (Europe), Borken, Germany
of Nijmegen,
The Netherlands
and *3M
Laboratories
ABSTRACT Results of dentine adhesion studies are influenced by many factors such as intrinsic and extrinsic dentine wetness. Relative air humidity and temperature are extrinsic environmental factors whose influence on dentine bonding capability is not precisely known. It was the aim of this study to gain an understanding of these factors as present in the mouths of patients and as influenced by several variables. In six different experiments the influence of application of a rubber dam, high and low relative humidity in the dental surgery, nose and mouth breathing and tooth drying was investigated. The results show that without application of a rubber dam there was no statistically significant difference in temperature for the variables nose and mouth breathing and tooth drying (mean 27.7 f 1S”C). Only the difference in relative air humidity of the dental surgery was statistically significant. With the application of a rubber dam the relative air humidity and temperature were essentially the same as the dental surgery conditions. It is concluded that without rubber dam the intraoral environment in which bonding procedures are to be performed is comparable with a high humidity climate such as that of Central Africa or the South Pacific. KEY WORDS: J. Dent. 1993)
1994;
Relative humidity, Intraoral, Rubber dam 22:
89-91
(Received
Correspondence should be addressed Department of Oral Function and Netherlands.
5 May
1993;
reviewed
Many dentine adhesion studies, although performed according to comparable protocols, show strongly differing results. Recently several publications have shown that the dentine bond strength of improved dental adhesive systems is negatively affected by intrinsic and extrinsic dentine wetnessle3. Other authors suggested that with a modified resin-primer mixture, dentinal surfaces exhibit dentine bonding capability in the presence of surface moisture4,5. In a recent experiment, extrinsic dentine wetness as caused by high air humidity during preparation of test samples gave significantly lower bond strength for most dentine bonding system@. Worldwide there are substantial climatologically and geographically dictated differences in temperature and relative humidity. Of course results of in vitro bonding experiments in these zones are influenced by the temperature and the relative humidity in the laboratory if these are not standardized or controlled by air conditioning. Clinically it is very Ltd.
1993;
accepted
24
August
to: Dr P. J. J. M. Plasmans, University of Nijmegen, Dental School, Prosthetic Dentistry, PO Box 9101, 6500 HB Nijmegen, The
INTRODUCTION
@ 1994 Butterworth-Heinemann 0300-5712/94/020089-03
20 June
important to have information on the temperature and relative humidity during operative procedures in the direct vicinity of the actual bonding application site, i.e. in the oral cavity. Surface temperatures of oral tissues have been reported by Spierings et al.‘. They found a surface temperature of the dentition of 30-35°C and for the soft tissues of 32-37 “C. The higher temperatures were found in the posterior part of the mouth. No information is available on the relative humidity during operative procedures. It was the aim of this study to investigate the relative humidity in the mouths of patients during operative procedures. Factors that could have an influence on the relative humidity are the location in the mouth, nose or mouth breathing and operative procedures such as tooth drying and application of rubber dam. Because both relative humidity and temperature influence the absolute amount of water vapour in the air (= absolute humidity), the temperature of the oral cavity was also recorded.
90
J. Dent.
1994;
22:
No. 2
Table 1. Summary of oral temperature and relative humidity as a function of ambient conditions and clinical treatment
Surgery conditions 1 (Nose)
Temp.: RH :
21.6”C 27.5%
2 (Mouth)
Temp.: : RH
21.6”C 27.5%
3 (Nose)
Temp.: 21.6”C RH : 27.5% Tooth drying Temp. : 23.3”C : RH 26.6%
78 (5)
Temp.: RH :
23.8”C 51 .O%
91 (4)
Temp.: RH :
23.8”C 51 .O%
97 (3)
Temp.: : RH
23.7 “C 30.8%
33 (4)
Figures in parentheses
MATERIALS
RH fW RH (96)
pooled
Temp. (“C) pooled
84 (6)
78 (5)
27.7
(1.5)
25.1
(1.9)
94 (4)
are standard deviations.
AND METHODS
In six different experiments the influence of application of a rubber dam, high/low relative humidity in the dental surgery, nose/mouth breathing and tooth drying were investigated. Measurements were made on 10 patients with one operator for all experiments. All the patients were attending the Dental School in Nijmegen for treatment. All relative humidity and temperature values were recorded with a Hygroscope GT (Rotronic, Zurich, Switzerland). This employed a solid-state humidity sensor sensitive to extremely small changes in humidity and a thermocouple (Pt 100) to measure the temperature. The following measurements were done: Experiment 1: The sensor was placed in the centre of the opened mouth. The final measurement was taken after stabilization of the sensor for 30 s in the mouth. The patient was allowed to breathe through the nose. Experiment 2: The sensor was placed in the centre of the opened mouth. Mouth breathing was enforced by holding the patient’s nose. The measurement was taken after 30 s stabilization. Experiment 3: The sensor was placed in the centre of the opened mouth. The patient breathed through the nose. The values were recorded after 30 s of stabilization. Tooth 36 was occlusally dried for 5 s by means of an air syringe, and a reading was immediately taken. The time taken to recover to initial values was also recorded. Experiment 4: Similar to experiment 2 but the relative air humidity in the dental surgery was maintained at a higher level.
Experiment 5: Similar to experiment 1. The relative air humidity in the dental surgery was maintained at a higher level. Experiment 6: Tooth 36 was isolated by means of a rubber dam. The sensor was placed and measurements were taken at least 15 min after application of the rubber dam. The sensor was placed as deep in the mouth as the rubber dam allowed. In all experiments care was taken not to touch the oral and/or the rubber dam. Before starting tissues the experiments, the patient was informed about the procedure.
RESULTS The results/circumstances of the respective experiments have been summarized in Table I. The temperatures of experiments 1, 2, 4 and 5 were analysed by means of ANOVA. No statistical differences were found. In experiment 3 (tooth 36 dried) both relative humidity and temperature fell, however, temperature recovered within 10 s. Extension of ANOVA analysis to experiments l-5 still did not show statistically significant temperature differences so these data were pooled. ANOVA of the relative humidity data revealed no statistically significant differences between nose and mouth breathing and so relative humidity values of experiments 1 and 2 as well as 4 and 5 were pooled. An ANOVA on the pooled data showed that the difference between high (experiment 4/5) and low (experiment l/2) relative air humidity in the dental surgery was statistically significant. The decrease
Plasmans:
in relative humidity in experiment 3 was not statistically significantly different from that in experiments 1 and 2. As with the temperature, relative humidity recovered within 10 s after tooth drying. In those cases where the patient was treated under rubber dam, relative humidity and temperature were essentially the same as those of the dental surgery.
Intraoral
humidity
during
operative
procedures
91
conditioned. Another implication may be that if it is not possible to achieve adequate intraoral moisture and humidity control, the bonding materials and procedures applied should be less sensitive to moisture and humidity. This is a definite challenge for manufacturers of dental bonding agents. The relatively high temperature and humidity levels may be detrimental to the bond quality of the majority of current dental adhesive systems.
DISCUSSION Dentine wetness as caused by high relative humidity and temperature may be a reason for differing results in testing dentine adhesives. The results of our research show that in some cases high humidity levels are present in the oral cavity. The influence of nose or mouth breathing was not significant. No allowance was made for location of measurement in the mouth. Measurements for lower first molars were made, as in our view these represent the worst case scenario for bonding procedures. The influence of compressed air used for drying the tooth was only measurable for about 10 s. The other operative procedure which could have influenced relative humidity and temperature was the application of a rubber dam. Results show that relative humidity as well as temperature are essentially the same as the dental surgery conditions. However the impression was sustained that a possible inverse relationship may exist between the length of the time elapsed after application of the rubber dam and the relative humidity. The same may be true for the influence of the operating light if directed at the operating site. For the latter case however the temperature may increase due to absorption of infrared light by the rubber dam. The practical consequence of this research is that a ‘dry’ working field in the oral cavity without the application of a rubber dam cannot be achieved. Even with the application of a rubber dam, the ambient dental surgery conditions have an influence on the relative humidity and temperature in the oral cavity. These ambient surgery conditions will vary on different days, at different times of the year and in different parts of the world. These variations will be greater if the dental surgery is not air-
CONCLUSIONS Without rubber dam the intraoral relative humidity is in the range 78-94% and temperature is in the range 26-29°C. Intraoral relative humidity does not depend on nose/ mouth breathing and tooth drying before measurement. Intraoral relative humidity in the mouth is dependent on the ambient relative humidity and temperature conditions. Relative humidity in the mouth cannot be controlled effectively without the use of a rubber dam. Rubber dam application results in virtually the same relative humidity and temperature intraorally as in the dental surgery.
References 1. Prati C, Pashley DH. Dentin wetness, permeability, thickness and bond strength of adhesive systems. Am J Dent 1992; 5: 33-38. 2. McGuckin RS, Tao L, Thompson WO. Shear bond strength of Scotchbond in vivo. Dent Mater 1991; 7: 50-53. 3. Fundingsland JW, Aasen SM, Bodger PD, Cemhous JJ. The effect of high humidity on adhesion to dentin. J Denf Res 1992; 72: (spec issue), (abstr 1199). 4. Kanca J. Effects of resin primer solvents and surface wetness on resin composite bond strength to dentin. Am JDent 1992; 5: 213-215. 5. Glasspoole EA Erickson RL, Pashley DH. In vitro bonding to wet dentin. J Dent Res 1992; 72: (spec issue), (abstr 795). 6. Plasmans PJJM, Reukers EAJ, Vollenbrock-Kuipers L, Vollenbrock HR. Air humidity: a detrimental factor in dentine adhesion. 1993. 7. Spierings ThAM, Peters MCRB, Plasschaert AJM. Surface temperature of oral tissue. J Biol Buccale 1984; 12: 91-99.
fa
22: 89-91
Intraoral humidity procedures
during operative
P. J. M. M. Plasmans, N. H. J. Creugers, R. J. Herm.sen* and M. M. A. Vrijhoef* TRIKON: Institute for Dental Clinical Research, University (Europe), Borken, Germany
of Nijmegen,
The Netherlands
and *3M
Laboratories
ABSTRACT Results of dentine adhesion studies are influenced by many factors such as intrinsic and extrinsic dentine wetness. Relative air humidity and temperature are extrinsic environmental factors whose influence on dentine bonding capability is not precisely known. It was the aim of this study to gain an understanding of these factors as present in the mouths of patients and as influenced by several variables. In six different experiments the influence of application of a rubber dam, high and low relative humidity in the dental surgery, nose and mouth breathing and tooth drying was investigated. The results show that without application of a rubber dam there was no statistically significant difference in temperature for the variables nose and mouth breathing and tooth drying (mean 27.7 f 1S”C). Only the difference in relative air humidity of the dental surgery was statistically significant. With the application of a rubber dam the relative air humidity and temperature were essentially the same as the dental surgery conditions. It is concluded that without rubber dam the intraoral environment in which bonding procedures are to be performed is comparable with a high humidity climate such as that of Central Africa or the South Pacific. KEY WORDS: J. Dent. 1993)
1994;
Relative humidity, Intraoral, Rubber dam 22:
89-91
(Received
Correspondence should be addressed Department of Oral Function and Netherlands.
5 May
1993;
reviewed
Many dentine adhesion studies, although performed according to comparable protocols, show strongly differing results. Recently several publications have shown that the dentine bond strength of improved dental adhesive systems is negatively affected by intrinsic and extrinsic dentine wetnessle3. Other authors suggested that with a modified resin-primer mixture, dentinal surfaces exhibit dentine bonding capability in the presence of surface moisture4,5. In a recent experiment, extrinsic dentine wetness as caused by high air humidity during preparation of test samples gave significantly lower bond strength for most dentine bonding system@. Worldwide there are substantial climatologically and geographically dictated differences in temperature and relative humidity. Of course results of in vitro bonding experiments in these zones are influenced by the temperature and the relative humidity in the laboratory if these are not standardized or controlled by air conditioning. Clinically it is very Ltd.
1993;
accepted
24
August
to: Dr P. J. J. M. Plasmans, University of Nijmegen, Dental School, Prosthetic Dentistry, PO Box 9101, 6500 HB Nijmegen, The
INTRODUCTION
@ 1994 Butterworth-Heinemann 0300-5712/94/020089-03
20 June
important to have information on the temperature and relative humidity during operative procedures in the direct vicinity of the actual bonding application site, i.e. in the oral cavity. Surface temperatures of oral tissues have been reported by Spierings et al.‘. They found a surface temperature of the dentition of 30-35°C and for the soft tissues of 32-37 “C. The higher temperatures were found in the posterior part of the mouth. No information is available on the relative humidity during operative procedures. It was the aim of this study to investigate the relative humidity in the mouths of patients during operative procedures. Factors that could have an influence on the relative humidity are the location in the mouth, nose or mouth breathing and operative procedures such as tooth drying and application of rubber dam. Because both relative humidity and temperature influence the absolute amount of water vapour in the air (= absolute humidity), the temperature of the oral cavity was also recorded.
90
J. Dent.
1994;
22:
No. 2
Table 1. Summary of oral temperature and relative humidity as a function of ambient conditions and clinical treatment
Surgery conditions 1 (Nose)
Temp.: RH :
21.6”C 27.5%
2 (Mouth)
Temp.: : RH
21.6”C 27.5%
3 (Nose)
Temp.: 21.6”C RH : 27.5% Tooth drying Temp. : 23.3”C : RH 26.6%
78 (5)
Temp.: RH :
23.8”C 51 .O%
91 (4)
Temp.: RH :
23.8”C 51 .O%
97 (3)
Temp.: : RH
23.7 “C 30.8%
33 (4)
Figures in parentheses
MATERIALS
RH fW RH (96)
pooled
Temp. (“C) pooled
84 (6)
78 (5)
27.7
(1.5)
25.1
(1.9)
94 (4)
are standard deviations.
AND METHODS
In six different experiments the influence of application of a rubber dam, high/low relative humidity in the dental surgery, nose/mouth breathing and tooth drying were investigated. Measurements were made on 10 patients with one operator for all experiments. All the patients were attending the Dental School in Nijmegen for treatment. All relative humidity and temperature values were recorded with a Hygroscope GT (Rotronic, Zurich, Switzerland). This employed a solid-state humidity sensor sensitive to extremely small changes in humidity and a thermocouple (Pt 100) to measure the temperature. The following measurements were done: Experiment 1: The sensor was placed in the centre of the opened mouth. The final measurement was taken after stabilization of the sensor for 30 s in the mouth. The patient was allowed to breathe through the nose. Experiment 2: The sensor was placed in the centre of the opened mouth. Mouth breathing was enforced by holding the patient’s nose. The measurement was taken after 30 s stabilization. Experiment 3: The sensor was placed in the centre of the opened mouth. The patient breathed through the nose. The values were recorded after 30 s of stabilization. Tooth 36 was occlusally dried for 5 s by means of an air syringe, and a reading was immediately taken. The time taken to recover to initial values was also recorded. Experiment 4: Similar to experiment 2 but the relative air humidity in the dental surgery was maintained at a higher level.
Experiment 5: Similar to experiment 1. The relative air humidity in the dental surgery was maintained at a higher level. Experiment 6: Tooth 36 was isolated by means of a rubber dam. The sensor was placed and measurements were taken at least 15 min after application of the rubber dam. The sensor was placed as deep in the mouth as the rubber dam allowed. In all experiments care was taken not to touch the oral and/or the rubber dam. Before starting tissues the experiments, the patient was informed about the procedure.
RESULTS The results/circumstances of the respective experiments have been summarized in Table I. The temperatures of experiments 1, 2, 4 and 5 were analysed by means of ANOVA. No statistical differences were found. In experiment 3 (tooth 36 dried) both relative humidity and temperature fell, however, temperature recovered within 10 s. Extension of ANOVA analysis to experiments l-5 still did not show statistically significant temperature differences so these data were pooled. ANOVA of the relative humidity data revealed no statistically significant differences between nose and mouth breathing and so relative humidity values of experiments 1 and 2 as well as 4 and 5 were pooled. An ANOVA on the pooled data showed that the difference between high (experiment 4/5) and low (experiment l/2) relative air humidity in the dental surgery was statistically significant. The decrease
Plasmans:
in relative humidity in experiment 3 was not statistically significantly different from that in experiments 1 and 2. As with the temperature, relative humidity recovered within 10 s after tooth drying. In those cases where the patient was treated under rubber dam, relative humidity and temperature were essentially the same as those of the dental surgery.
Intraoral
humidity
during
operative
procedures
91
conditioned. Another implication may be that if it is not possible to achieve adequate intraoral moisture and humidity control, the bonding materials and procedures applied should be less sensitive to moisture and humidity. This is a definite challenge for manufacturers of dental bonding agents. The relatively high temperature and humidity levels may be detrimental to the bond quality of the majority of current dental adhesive systems.
DISCUSSION Dentine wetness as caused by high relative humidity and temperature may be a reason for differing results in testing dentine adhesives. The results of our research show that in some cases high humidity levels are present in the oral cavity. The influence of nose or mouth breathing was not significant. No allowance was made for location of measurement in the mouth. Measurements for lower first molars were made, as in our view these represent the worst case scenario for bonding procedures. The influence of compressed air used for drying the tooth was only measurable for about 10 s. The other operative procedure which could have influenced relative humidity and temperature was the application of a rubber dam. Results show that relative humidity as well as temperature are essentially the same as the dental surgery conditions. However the impression was sustained that a possible inverse relationship may exist between the length of the time elapsed after application of the rubber dam and the relative humidity. The same may be true for the influence of the operating light if directed at the operating site. For the latter case however the temperature may increase due to absorption of infrared light by the rubber dam. The practical consequence of this research is that a ‘dry’ working field in the oral cavity without the application of a rubber dam cannot be achieved. Even with the application of a rubber dam, the ambient dental surgery conditions have an influence on the relative humidity and temperature in the oral cavity. These ambient surgery conditions will vary on different days, at different times of the year and in different parts of the world. These variations will be greater if the dental surgery is not air-
CONCLUSIONS Without rubber dam the intraoral relative humidity is in the range 78-94% and temperature is in the range 26-29°C. Intraoral relative humidity does not depend on nose/ mouth breathing and tooth drying before measurement. Intraoral relative humidity in the mouth is dependent on the ambient relative humidity and temperature conditions. Relative humidity in the mouth cannot be controlled effectively without the use of a rubber dam. Rubber dam application results in virtually the same relative humidity and temperature intraorally as in the dental surgery.
References 1. Prati C, Pashley DH. Dentin wetness, permeability, thickness and bond strength of adhesive systems. Am J Dent 1992; 5: 33-38. 2. McGuckin RS, Tao L, Thompson WO. Shear bond strength of Scotchbond in vivo. Dent Mater 1991; 7: 50-53. 3. Fundingsland JW, Aasen SM, Bodger PD, Cemhous JJ. The effect of high humidity on adhesion to dentin. J Denf Res 1992; 72: (spec issue), (abstr 1199). 4. Kanca J. Effects of resin primer solvents and surface wetness on resin composite bond strength to dentin. Am JDent 1992; 5: 213-215. 5. Glasspoole EA Erickson RL, Pashley DH. In vitro bonding to wet dentin. J Dent Res 1992; 72: (spec issue), (abstr 795). 6. Plasmans PJJM, Reukers EAJ, Vollenbrock-Kuipers L, Vollenbrock HR. Air humidity: a detrimental factor in dentine adhesion. 1993. 7. Spierings ThAM, Peters MCRB, Plasschaert AJM. Surface temperature of oral tissue. J Biol Buccale 1984; 12: 91-99.