ABSTRACT

Objective: To evaluate the effectiveness of nitrous oxide oxygen inhalation sedation as an adjunct to dental  behaviour  management  and  allowing  the  treatment  to  be carried out  for children.                                       

Methods: The dental records of 224 patients, belonging to healthy children were examined.

Results:  The  administration of  nitrous oxide-oxygen  gas  mixtures  in the range of 30%-39%  profoundly influenced  the behaviour of  anxious children enabling them to co-operate  and  allow  satisfactory  dental  treatment to be carried out.  There was a significant relationship between the use of local anesthesia and the successful outcome of   treatment.  The acceptance of   inhalation sedation was not related to the gender of the patient.  There was a significant relationship between the age of the patient and success of inhalation sedation.

Conclusion: Nitrous oxide was found to have significant effect on uncooperative child behaviour.

Key words: Inhalation sedation, Nitrous oxide, Pediatric dentistry

JRMS March 2010; 17(1): 38-42

Introduction

Inhalation  sedation  utilizing nitrous oxide  and  oxygen has been a primary technique in  the management of  dental  fears and  anxieties  for  more  than 150  years and remains so today.^(1,2) The terms “nitrous oxide sedation”, “relative   analgesia   (RA)”   and “inhalation sedation” are frequently used to describe the same technique. Though earlier recommendations suggested an upper limit of  30% nitrous oxide,⁽³⁾  it  has  been  recognized  that  flexibility  may  be  required and a more recent recommendation justifies an upper limit of 70% nitrous oxide, 30% oxygen.⁽⁴⁾

Sedation by  the  introduction  of   nitrous  oxide is   relatively  safe, simple and  is  effective  in  reducing  the anxiety  and  fear in patients.⁽⁵⁾ Increasing awareness of the potential risks of dental general anesthesia  (DGA) led to the development of an Expert Working Party to assess the future of  DGA in dentistry in the UK.

One of its principal recommendations was avoidance of DGA and the use of alternative techniques whenever possible.⁽⁴⁾ The mean cost of sedation was one-third that of general anesthesia.⁽⁶⁾

Inhalation sedation with nitrous oxide-oxygen has proved to be one of the most effective techniques for the reduction of stress in the apprehensive or medical risk patient.⁽²⁾  When   highly  anxious children  are treated  with nitrous oxide for a number of consecutive sessions, their anxiety remains significantly lower during  a following control  period even without the use  of   nitrous oxide.^(7,8)  

Inhalation sedation using nitrous oxide is widely used in dentistry to alleviate dental anxiety and improve patient cooperation.⁽⁹⁾  

Nitrous oxide-oxygen sedation for pediatric patients is an essential tool in anxiety management   and is used as an adjunct to behavioural management.⁽¹⁰⁾

Methods

Records of children, aged 6-15 years, who were treated  by postgraduate students and Senior House Officers in the Pediatric Dentistry Department  of  the Liverpool  University  Dental   Hospital   between   March  1,  2003   and   March  30,   2004   after   being  referred   by  General  Dental   Practices  and   Community  Dental   Service  Clinics because  of   inability  to  co-operate with  dental treatment were reviewed.   Children whose dental records mentioned learning difficulty were excluded from the study. The dental records of 224 patients, belonging to healthy children, were examined.

The collected data (Appendix 1) were edited, coded and entered on a PC and analyzed with the SPSS statistical package, version 11. 

Results

Eighteen patients were excluded from the study, because of their age, 11 patients were older than 15 years and seven were younger than six years. Six patients were also excluded from the study because it was not possible to complete the data from the dental records.

The main study group therefore consisted of a total of 200 patients who attended the clinic for treatment with inhalation sedation. These patients had a total of 389 visits. 

Table I is a summary of treatment outcome for the 200 patients for whom treatment with inhalation sedation was planned. For 153 (76.5%), all the planned treatment was completed using inhalation sedation. There were thirty five (17.5%) patients who could not complete treatment in this way and were subsequently treated using Dental General Anesthesia (DGA). The remaining twelve patients (6%) did not complete treatment because they failed to attend second or subsequent visits, having previously accepted part of the planned treatment successfully.  For those thirty five patients who were referred on for DGA, twenty four were sent because treatment had to be abandoned at the first visit, five at the second visit, two at the third visit and four at the fourth visit.  The  reasons  for  abandoning treatment for  these patients  were:  “Refusal  of  sedation” by  five patients;  “Refusal of  local anesthesia” (LA) (despite  acceptance  of  sedation) by seventeen patients; “Refusal of extraction” (despite adequate LA and acceptance of sedation) by six patients; “other” reasons for seven patients. For four of these seven patients there was inadequate analgesia, two patients for extraction and two patients for endodontic treatment.  The remaining three patients became very nervous and started crying. For  the twelve  patients  who failed  to  attend  to  complete  their  treatment, six  failed  to return for a second visit, four for a third visit and two for a fourth visit.  

Factors Related to the Outcome of Proposed Treatment with Inhalation Sedation and General Anesthesia: 

I. Gender

The study group of children consisted of 103 (51.5%) males and 97 (48.5%) females.  It  is  shown  in  Table II  that  of  the 153  children  who completed their treatment plans, there were seventy six males and seventy seven females.

Of the thirty five patients referred on for DGA there were twenty males and fifteen females. Of the twelve patients who did not complete their treatment plans, there were seven males and five females. 

Table III.   Percentage of nitrous oxide used for patients who completed treatment

Analysis of   these results showed that there was no statistically significant relationship between the gender of the child and the management technique (P> 0.05).

II. Age

The mean age of patients who completed their treatment plans is 25.7 months (SD 34.51). The forty seven patients for whom treatment was not completed with sedation, their mean age was 103.5 months (SD 23.42).  Analysis of the data demonstrated that there was a statistically significant difference in age between the two groups (p < 0.05(.

III. Concentration of Nitrous Oxide

Table III shows the percentage of nitrous oxide for patients who completed their treatment plans.  Of these 153 patients, 30 (19.6%) received 20-29% nitrous oxide, 116 (75.8%) received 30-39% nitrous oxide and   7(4.6%) received 40-45% nitrous oxide.  The minimum concentration used was 20% and the maximum concentration was 45%.

IV. Local Anesthesia

Of the 177 patients who were treated with LA, 152 (85.9%) completed treatment.  LA was not used for twenty three patients.  Only one (4.3%) of these completed the treatment plan.  Of the twenty two patients for whom LA was not possible, seventeen   were referred to DGA and five did not return for treatment in the study period. There was a statistically significant difference between patients treated with LA and those patients for whom it was not possible to use LA (P<0.05).    

Discussion

The age group chosen was children between six and fifteen years old. This range was chosen because younger children are more likely to require DGA, while older children may accept treatment with local anesthetic only.⁽¹¹⁾ 

The overall success rate of 76.5% of patients completing all their planned treatment is comparable to that of most previously reported studies relating to the efficacy of treatment with inhalation sedation, Roberts et al,⁽¹²⁾ Lindsay and Roberts⁽¹³⁾ and Bryan.⁽¹¹⁾

Forty-seven of the 200 patients did not complete their treatment.  However, it must be noted  that failure rate  of  23.5% included twelve patients (6%) who failed to attend for second or subsequent visit having  previously accepted part of  the planned treatment successfully.  The reasons for this failure to return for completion of treatment were not investigated.

Thirty-five of  the patients  (17.5%)  could  not cope  with  treatment  using sedation  and were  subsequently  treated using DGA.  This  result  implies  that  there will always  be  a small number of patients for  whom  treatment   with  inhalation  sedation  will  be  unsuccessful. This contrasts with DGA, where a competent anesthetist may be able to induce most children, because co-operation is necessary for only a very short   time before loss of consciousness. It is therefore of value to examine the factors associated with success in this study.

Analysis of the results showed that there was no relationship between gender and the management technique.  

Children at the upper limit of the age group might have been expected to have a more favorable   attitude towards inhalation sedation.   This study confirmed that the likelihood of success is related to the age of patients and it was shown that the patients who failed to complete their treatment were approximately two years younger than those who completed their treatment.  

The results of this study demonstrated that there was  a  statistically significant  difference  between  the  mean  age  of  patients  who completed  treatment compared  with those who did not. Weinstein et al.⁽¹⁴⁾ noted that children under six years of age did not respond to inhalation sedation and Hallonston et al.⁽¹⁵⁾ also found a lower acceptance level with younger patients. The findings of the dental assessment raise a number of important issues related to the concentrations of nitrous oxide recommended.  A fixed concentration 25%  nitrous oxide has been suggested by Edmund and Rosen.⁽¹⁶⁾   It is apparent that if this concentration was used, it would be insufficient for large number of patients.  A maximum concentration of 50% has been suggested by Young, O’Mullane and Warren.⁽¹⁷⁾ 

This concentration was not used for any patient in this study, and the average concentration used for patients completing their treatment plans was 30.25% nitrous oxide with 75.8% of patients receiving 30-39% of nitrous oxide.  His supports the idea suggested by Bennett⁽¹⁸⁾  that adequate sedation is likely to be achieved for most  patients when inhaling between 30% and 35% nitrous oxide, also Stanley and Morris⁽²⁾  ascertained  that  the typical  inhalation sedation  patient  requires 30-40% nitrous  oxide.  Compared to this study, Roberts et al.⁽¹²⁾ reported a higher concentration, of 47-50%. They also suggested the need for even higher concentrations. However, Hallonsten et al.⁽¹⁵⁾ demonstrated that concentrations higher than 60% nitrous-oxide  are  not necessary with slow introduction and  without the use of an air dilution port.

This   study  showed  a  highly  statistically  significant  difference between  patients treated  with  LA and  patients for whom it was not  possible to use LA.   Nitrous oxide-oxygen sedation was supplemented with LA in 88.5% of the patients where operative dentistry or dental extraction was performed, to achieve satisfactory pain control.   The use of LA is supported by Trieger et al.⁽¹⁹⁾  who concluded that supplementation with local  analgesia  is frequently necessary to obtain sufficient pain control in both operative dentistry and  oral surgery.  LA was not used for 23 (11.5%) study patients.  Most of those were referred to DGA.

Conclusion

It  was   possible  to  treat  a  large  proportion  of  the  patients  using  this   alternative approach, who would otherwise need DGA.

The administration of nitrous oxide-oxygen  gas  mixtures  in  the range of 30%-39%  profoundly  influenced  the  behaviour of  children  enabling them to co-operate and allow satisfactory dental treatment to be carried out.  There  was a  significant   relationship  between  the  use  of   LA  and   the  successful  outcome   of  treatment.

References

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