Patient satisfaction and quality of life status after 2 treatment modalities: Invisalign and conventional fixed appliances


Our objectives were to assess patient satisfaction and quality of life among adults via 2 validated comprehensive questionnaires and to compare patient satisfaction and status in oral health-related quality of life immediately after orthodontic treatment in patients treated with Invisalign (Align Technology, San Jose, Calif) and those who received standard bracket-based treatment.


Adult patients (n = 145) treated with bracket-based or Invisalign therapy were recruited from several private practices and a university clinic. The survey comprised a combination of the Dental Impacts on Daily Living index and the Patient Satisfaction Questionnaire. This 94-question assessment focused on various dimensions of satisfaction and quality of life. Multivariate analysis of variance and the bootstrap test were applied. A reliability analysis was used to assess responses at a 6-month follow-up for a small sample of patients.


Finally, 122 patients were assessed. The multivariate analysis of variance analysis showed that the eating and chewing dimension was significantly different between the 2 groups (Invisalign, 49%; bracket based, 24%; P = 0.047). No significant difference in any other satisfaction factors (all, P > 0.05) was identified. The follow-up assessment was only possible in a small sample of the bracket group; it showed adequate reliability values on the categories of oral comfort (intraclass correlation coefficient [ICC], 0.71), general performance (ICC, 0.755), situational (ICC, 0.80), and doctor-patient relationship (ICC, 0.75).


Of the patients surveyed to assess their satisfaction and oral health-related quality of life immediately after completion of their orthodontic treatment, both the bracket-based and Invisalign treated patients had statistically similar satisfaction outcomes across all dimensions analyzed, except for eating and chewing: the Invisalign group reported more satisfaction. Patient satisfaction remained relatively similar 6 months later for the bracket-type treatment.


  • Invisalign and conventional bracket patients were generally equally satisfied with their treatment outcomes.

  • Only “eating and chewing” category differed between groups.

  • Invisalign patients were less dissatisfied while eating and chewing than were conventional bracket patients.

Patient satisfaction, as related to oral health care, can be defined as a patient’s personal evaluation of the services provided to him or her. It can be used as 1 measure of the overall quality of health care; therefore, it has resulted in increased interest in quantifying and qualifying patient satisfaction with dental treatment. Nonetheless, due to different motivations and expectations for seeking oral health care, professional assessments of treatment outcomes may differ from those of their patients. This is also true for orthodontic treatment, where motivation to seek treatment includes esthetics, improved dental function, and psychological benefit; these motivations occur at different degrees in different patients, and younger patients may even lack motivation for treatment since they are brought in by their parents.

Previous studies examining patient satisfaction with fixed appliances have suggested that some patients may experience pain and discomfort immediately after orthodontic appliances are bonded as well as sometimes after regular visits. This was negatively correlated with patient satisfaction. However, at the end, the vast majority of patients were satisfied with the outcomes of their orthodontic treatment. Furthermore, although temporary negative effects on function and social and emotional well-being are expected as side effects of standard bracket-based treatment, these effects were significantly less than what patients expected before starting treatment.

Clear aligners were introduced to provide orthodontic treatment with a more esthetic, removable appliance. However, a previous study showed that 50% of patients undergoing Invisalign (Align Technology, San Jose, Calif) treatment were self-conscious about their appearance during treatment. Most patients reported satisfaction with the results of their orthodontic treatment and improvement in self-confidence after treatment. Furthermore, oral health-related quality of life (OHRQoL) was only minimally affected during treatment.

There are many factors to consider when choosing between clear aligners and conventional bracket-based treatment. The ability to remove the clear aligners may make it easier for patients to maintain good oral hygiene, but studies have shown conflicting results. One study suggested poorer gingival health in the bracket-based group compared with the Invisalign group but equal plaque accumulation between the 2 groups in a sample of adults and children. Another study showed that subjects with the fixed appliance modality retained more plaque, but the gingival health between the 2 treatments was nearly identical. Patient satisfaction was reported to be higher in the Invisalign group, with these patients reporting more willingness to redo the same treatment, fewer changes in eating habits, and less decrease in overall well-being during treatment.

Few studies have combined the effects of different treatment modalities on adult patient satisfaction and quality of life (QoL). Most previous studies assessing satisfaction applied nonvalidated questionnaires; some used only 1 question or a few questions addressing satisfaction as an overall statement. These tools could be considered susceptible to subjectivity and likely compromise the reliability or internal validity of the questions. Therefore, in this study, we aimed to assess adult patients’ satisfaction and OHRQoL status immediately after orthodontic treatment via 2 validated, wide-ranging questionnaires and to compare patient satisfaction and changes in OHRQoL immediately after orthodontic treatment on patients who had Invisalign or bracket-type treatment.

Material and methods

Approval from the Research Ethics Board at the University of Alberta in Canada was granted for the protocol and informed consent process of this study (Pro00056779). An observational cross-sectional study was planned to compare the factors related to treatment satisfaction and OHRQoL status in adult orthodontic patients treated with either the Invisalign (Align Technology, San Jose, Calif) system or a bracket-based system.

All adult patients, whose last orthodontic appointment before completion of treatment occurred between November 2014 and October 2016 were consecutively invited to participate in the survey during their debonding appointment. Because this was a cross-sectional study, no sample size was calculated. This was a convenience sample of all patients willing to participate in a given time period. We included adults (older than 18 years) treated exclusively with either the Invisalign system or standard brackets. We excluded patients with previous orthodontic treatment combined with orthognathic surgery, retreatments with either treatment modality, or clear aligners combined with fixed orthodontic appliances or vice versa. Otherwise, any malocclusion complexity was considered.

Group 1 included Invisalign system orthodontic patients recruited from 4 private practices in Edmonton, Calgary, Vancouver, and Toronto, Canada. Group 2 originated from current patients treated exclusively with conventional fixed appliances (brackets) at the Orthodontic Graduate Clinic at the University of Alberta in Edmonton, Alberta, Canada. A small sample of this last group was retested during the 6-month retention appointment to explore short-term changes. This retest aimed to explore patient consistency in satisfaction levels after a certain period of time: 6 months.

The invited patients received a pamphlet at the front desk containing all the information regarding the survey and the informed consent to be signed ( Appendix 1 ). They had an opportunity to clarify their concerns verbally with a representative of the research project in each location. The representatives were calibrated by a member of the research project team (C.P.P.). Both groups and all invited patients had access to the e-mails and phone numbers of the research project team for further contact if they needed more clarification.

Two previously validated questionnaires, the Dental Impacts on Daily Living (DIDL) index and the Patient Satisfaction Questionnaire (PSQ), were used. The survey answered by the patients included 94 questions in total, combined into 2 parts. Parts I and II were unified using survey software (SurveyMonkey, Palo Alto, Calif) and administered on an iPad (Apple, Cupertino, Calif) or on a paper version (the same format) as an alternative. All participants completed the survey in the waiting room after checking in for their appointment.

Part I, the DIDL questionnaire, addressed 5 dimensions of life: appearance, pain, comfort, general performance, and eating restriction, all from the patient’s perspective. This tool allowed patients to give weight to the different categories, providing a weighted dimension score, making the results more specific to each patient. Patients responded to the 36 items in a binary manner by indicating whether the statement applied to them. Each category contained between 4 and 15 statements; these items and the analysis process of the answers are listed in detail in a previous questionnaire validation article. At this point, the patients could select the sentences that applied to their daily lives (survey design in Appendix 2 ).

The PSQ (part II) explored the nuances of patient satisfaction, investigating factors related to the doctor-patient relationship, situational aspects, psychosocial and dentofacial improvements, and dental function, with each category containing between 4 and 15 questions. In this section, the patients responded to the 58 questions using a 5-point scale, ranging from completely disagree (1 point) to completely agree (5 points). The responses were quantified and analyzed for each satisfaction factor. The questions and their validations were published in detail previously. The complete survey, including both parts I and II, is shown in Appendix 2 .

For the survey given to Invisalign patients, “fixed appliance” was replaced with “Invisalign” in all questions. Strategies to raise response rates during the retest such as telephone confirmation of the appointment or a reminder of the invitation to reanswer the survey during the 6-month appointment were used to increase the number of respondents. All data collected were blinded from the research team except for 1 member (C.P.P.) and transferred to an Excel spreadsheet (Microsoft, Redmond, Wash) for third-party statistical analysis. Neither the researchers nor the practitioners or graduate students had access to the confidential information or identifiers on the survey answers from participants.

Statistical analysis

The Statistical Package for the Social Sciences (version 24; IBM, Armonk, NY) was used for statistical analysis, and the data were analyzed by an independent statistical service.

The DIDL answers to each question were categorized as positive (1), negative (−1), or neutral (0) and then averaged for each dimension, according to the validated method. Each dimension score was normalized based on the weighting the patient gave it, and the weighted scores for each dimension were totalled. Tests were carried out to determine whether there was a statistical difference between the answers of patients from the private practices. Multivariate analysis of variance (MANOVA) was used to compare all averages in each dimension and the 2 overall averages, and we investigated whether distributions were significantly different between locations. For subjective impact data analysis, the participants were grouped into 3 levels of impact: those who were satisfied (scores, 1.0-0.7), those who were relatively satisfied (scores, 0.69-0), and those who were dissatisfied (scores, <0); these cutoff values were validated by the DIDL authors. This was done for each of the 5 DIDL dimensions and also for the overall scores. The participants could check a box after a statement if they believed that the statement applied to them; not checking the box was considered a neutral response (0 value). Each dimension only contained either positive statements (+1) or negative statements (−1). P values and confidence intervals were calculated using the bootstrap method.

Scores for the PSQ factors and the DIDL dimensions were compared between the Invisalign and bracket-based patients using MANOVA. It was used to simultaneously analyze the impact of many variables instead of running multiple independent t tests that would have increased the chance of type I error (false positive). A P value less than 0.05 was considered statistically significant. A bootstrap test was used to estimate the P value for the variable that was statistically significant in MANOVA.

A reliability test was applied at different times, immediately after debonding and 6 months after the active treatment; the intention was to detect a trend in the bracket-based participants’ answers at a 6-month reassessment. The intraclass correlation coefficient (ICC) was used and interpreted according to the guidelines of Portney and Watkins : 0-0.2, poor agreement; 0.3-0.4, fair agreement; 0.5-0.6, moderate agreement; 0.7-0.8, strong agreement; and more than 0.8, almost perfect agreement.


The survey was open during a 22-month period, and consecutive patients were invited to participate. Although initially 145 patients participated, the response rate was 84.1%. Thirteen participants from the private practice cohort and 10 from the university cohort did not complete the survey properly and were later excluded from the analysis. Eighteen patients requested to answer the survey on the paper version; they were not comfortable with the tablet form. Data from a total of 122 participants were included; from these participants, 3 sociodemographic variables were investigated: sex, age range, and location. A total of 33 men (27%) and 89 women (73%) participated ( Fig 1 ). The mean and mode age ranges were between 18 and 25 years.

Dec 8, 2018 | Posted by in Orthodontics | Comments Off on Patient satisfaction and quality of life status after 2 treatment modalities: Invisalign and conventional fixed appliances
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