Evaluating Post-Insertion Complications and Patient Satisfaction of Conventional Complete Dentures: A Retrospective Study

Abstract

Conventional complete dentures remain to be an important treatment for edentulous patients, especially those of low socioeconomic status. This study is a retrospective analysis that aims to elucidate influencing factors of post-insertion complications and patient satisfaction. Clinical records of 164 patients who received both maxillary and mandibular complete dentures at an Australian university teaching clinic were assessed and analysed. The parameters considered include reason for attendance, presenting clinical status, experience of operator, numbers of appointments for fabrication and adjustment, post-insertion complications and events, and patient satisfaction. The differences among selected attributes were analysed using a Mann–Whitney test, Chi-square test, or Kruskal–Wallis test where applicable, while the relationships between discrete variables were assessed by Kendall’s correlation. First, the number of appointments for fabrication differed significantly between female (6.8 ± 1.8) and male patients (6.2 ± 1.3; p = 0.025) and between student (6.7 ± 1.7) and professional operators (6.0 ± 1.1; p = 0.015). The number of appointments for adjustment was significantly associated with patient age (τ_b = 0.167, p = 0.003) and sharply declined after the first three months. Second, post-insertion pain was the most frequent complication, and it was significantly more associated with the mandible than the maxilla (χ² = 21.670, p = 0.000). Similarly, mandibular complete dentures were also significantly more associated with post-insertion reline than the maxillary (χ² = 8.804, p = 0.003). Lastly, patient satisfaction was significantly associated with patient attendance with old/worn dentures (χ² = 9.468, p = 0.002), as well as the absence of retention/stability issues (χ² = 41.712, p = 0.000), post-insertion reline (χ² = 29.300, p = 0.000), or denture replacement (χ² = 13.968, p = 0.000). Dissatisfied patients had a significantly higher age (70.9 ± 11.0 vs. 66.2 ± 12.6; p = 0.023) and number of appointments for adjustment (4.9 ± 3.5 vs. 3.1 ± 2.1; p = 0.001) than satisfied patients. In summary, these findings revealed the above factors that influence the fabrication process, post-insertion complication, and patient satisfaction of conventional complete dentures. Future research may include analysis of cases completed at private practices and consideration of other potentially relevant factors such as denture usage and mental status.

1. Introduction

Complete edentulism or total tooth loss usually takes place after initial periods of partial tooth loss and can be a result of dental caries, periodontal diseases, or unpreferred treatments due to cost barriers [1,2]. It directly causes impaired masticatory function, leading to unhealthy diets [2]. Associated general health issues include malnutrition, hypertension, and obesity [3]. The quality of life of patients is also compromised by the resulting psychological and social impairments [2,3]. In Australia, 4.0% of the total population and 20.5% of the population aged above 75 were edentulous in 2017 to 2018 [3]. Even though there has been a decline in its prevalence over the last decade, the increases in life expectancy and the elderly population are predicted to further aggravate the burden of edentulism [4,5,6].

Common treatments for complete edentulism include complete removable dentures and implant-supported prostheses [7,8]. Compared with the traditional complete dentures, the latter requires much higher financial cost, which is a major consideration influencing the treatment preferences of edentulous patients [7]. Patients who received complete dentures were found to be more economically disadvantaged than those who received implant-supported prostheses [7]. Meanwhile, there is a higher prevalence of edentulism in lower socioeconomic groups that have a tendency to avoid dental care due to its cost [3,4,5,7,9]. Hence, the provision of high-quality conventional dentures remains immensely important in the management of complete edentulism, especially in the public sector, which manages the majority of the edentulous population [3].

Although simplified techniques of complete denture fabrication have been introduced to reduce the number of appointments [10,11], the conventional technique is still taught at most universities and used widely [12]. The standard procedure for complete denture fabrication typically involves five appointments which are as follows: preliminary impressions, final impressions, jaw registration using wax blocks and facebow transfer, wax try-in, and final insertion [12]. It is then during the period of post-insertion review that the operator is responsible for providing the necessary care such as adjustments of the denture [13]. This period varies among patients, as the first post-insertion review appointment is arranged by the operator, while the subsequent reviews usually depend on the need of the patient [13]. A number of post-insertion complications could potentially take place, and the common ones include loss of retention, debonding/fracture of artificial teeth, fracture of denture base, and denture irritation/ulceration [6,14,15]. However, there are currently insufficient empirical data on the duration of the post-insertion phase of complete dentures and the resolution of related complications.

The quality of dentures can be assessed by certain parameters, including retention, stability, occlusion, and aesthetics. First, retention is defined as the resistance to the forces of dislodgment along the path of placement in the vertical direction [13,16]. Base tissue contact, base extension, and border seal are the key factors to be maximised for effective retention [17]. In contrast, stability is the resistance to the forces of dislodgment in the horizontal direction, and the vertical height of the residual ridge and quality of the impression are important to achieve this [13,16]. Third, balanced occlusion allows the occlusal forces to be evenly distributed across the denture [13,18]. Occlusal imbalance is another contributor compromising denture stability [18]. Finally, aesthetics is also a major consideration, as the restoration of a natural appearance allows patient confidence in social interactions [13,15].

In addition to the high quality of the dentures and the absence of post-insertion complications, the success of complete dentures also requires patient satisfaction. In other words, the treatment success is assessed not purely by clinical factors or technical quality but also by the subjective experience or opinion of patients [6,8,14]. The provision of a technically and clinically excellent conventional complete denture does not guarantee patient satisfaction or treatment success [6,14]. Statistically, the correlations between patient satisfaction and the objective measurements of denture quality such as retention and stability were found to be weak and often non-significant [6]. There is thus currently no method to reliably predict the treatment success of complete dentures [19].

Nonetheless, several “prognostic indicators” of the treatment success have been identified by different researchers [20]. For example, Leles et al. found that increased patient age was negatively associated with the masticatory performance of complete dentures [21]. Although this study also found the masticatory performance to be higher in females than males [21], Alves et al. showed opposite results [22]. In another pilot study, women showed greater satisfaction scores for aesthetics than men [23]. Also, ratings of patient general satisfaction and satisfaction on speaking, stability, and retention were higher when the complete dentures were fabricated by dentists with over ten years of prosthodontic experience than by inexperienced dentists [24]. Lastly, the overall denture satisfaction was found to be significantly correlated with the stability and the retention of mandibular complete dentures but not with the stability or the retention of maxillary complete dentures [25]. This indicates potential differences in post-insertion complications and patient satisfaction between maxillary and mandibular complete dentures.

The current literature provides insufficient information on the duration of the post-insertion phase, differences in complications of maxillary and mandibular complete dentures, and factors affecting patient satisfaction. This study aims to use clinical records of patients who received both complete maxillary and mandibular dentures simultaneously at an Australian university teaching dental clinic to retrospectively assess the following:

• The numbers of fabrication appointments and post-insertion reviews, the rates of post-insertion complications and events, and their relationships with patient factors such as age and gender, as well as with operator experience;
• The differences in post-insertion complications and events between maxillary and mandibular complete dentures;
• The relationships between patient satisfaction and various factors including patient age and gender, presenting clinical status, operator experience, and numbers of fabrication appointments and post-insertion reviews, as well as post-insertion complications and events.

2. Materials and Methods

2.1. Ethical Principles

The ethical clearance for the data collection (GU Ref No: 2019/119) was obtained from the Office for Research, Griffith University (Gold Coast, QLD, Australia).

2.2. Study Design

The data used in this study were obtained by analysing the records of patients attending the Griffith University Dental Clinic (Gold Coast, QLD, Australia) stored on the Titanium electronic patient records system (Titanium Software, Houston, TX, USA). At the university clinic, the in-chair appointments were performed by either undergraduate dentistry students under supervision or by professional dentists employed by the university. The denture fabrication was performed by dental technicians employed by an in-house dental laboratory at the university. Prior to the denture construction phase, patients had completed comprehensive examinations; all necessary treatments had been given to ensure they were free of active dental decay and periodontal diseases. The soft tissue condition, including the presence of flabby tissue and ridge resorption after extractions, was recorded and considered in the denture design. After the final denture insertion, one post-insertion review appointment after one to two weeks was always arranged by the operator, although there were rare cases that patients failed to attend or respond. Subsequent follow-up appointments were scheduled as patients requested.

Records of all patients who received treatment with complete maxillary and mandibular dentures (specified by the code 719 in the Australian Schedule of Dental Services and Glossary) between 2011 and 2014 were screened. All patients who did not meet any exclusion criteria were included in this study. These exclusion criteria were lost dentures, incomplete records, implant-supported complete dentures, overdentures, immediate dentures, and dentures fabricated by more than one operator.

The interpretation of the records on Titanium was performed by three dental clinicians by following standardised criteria of the assessment parameters (

Table 1. The assessment parameters of patient records.

Parameter	Category	Criteria
Reason for attendance	Lack/loss of teeth	Patient being edentulous and never having had dentures or patient having poor dentition and needing extractions before denture fabrication
	Old/worn denture	Dentures being over 5 years old or patient’s comment of the current denture being old
	Poor-quality denture	Patient’s complaint of current denture or clinician’s judgement of poor-quality denture
	Miscellaneous Undocumented	Aesthetic issues or lost dentures No documentation on reasons for attendance
Presenting clinical status	Edentulous	Patient presenting as edentulous
	Extraction needed	Patient presenting with poor dentition which had to be extracted prior to fabrication of new dentures
Operator fabricating dentures	Student Professional	Undergraduate dental and prosthetist student Prosthodontist, dentist, or prosthetist
Number of appointments for fabrication
Number of appointments for adjustment		Number of follow-up appointments at 0 to 3 months, 3 to 12 months, 12 to 24 months, 24 to 60 months, and over 5 years; follow-up appointments only up to the date of the first post-insertion event
Post-insertion complications	Pain Retention/stability issue Occlusion issue Aesthetic issue
Post-insertion events	Reline Denture base fracture Loss of artificial teeth Replacement of denture
Patient satisfaction	Satisfied	Documentation of patient satisfaction within 6 months; presence of phrases such as “comfortable”, “happy”, “satisfied”, or “likes aesthetics” in the clinical records; no documentation of reline or replacement within 12 months of fabrication
	Unsatisfied	Documentation of patient unsatisfaction within 6 months; documentation of reline or replacement within 12 months of fabrication
	Undocumented	No documentation on patient satisfaction

). The records were first assessed by two of the clinicians independently and were then reviewed by the third clinician who made the final corrections.

2.3. Assessment Parameters

The parameters assessed for each patient included in this study (Table 1) were as follows:

• Reason for attendance (lack/loss of teeth, old/worn denture, poor-quality denture, or miscellaneous);
• Presenting clinical status (edentulous or extraction needed);
• Operator fabricating dentures (student or professional);
• Number of appointments for fabrication;
• Number of appointments for adjustment;
• Post-insertion complications (pain, retention/stability issue, occlusion issue, or aesthetic issue);
• Post-insertion events (denture base fracture, reline, loss of artificial teeth, or replacement of denture);
• Patient satisfaction.

2.4. Statistical Analysis

All statistical analyses were performed using IBM SPSS Statistics version 26 (IBM, Armonk, NY, USA). Descriptive data were summarised using frequencies, percentages, means, maximums, and/or minimums. The significance levels of differences among the selected attributes were analysed using a Mann–Whitney test, Chi-square test, and Kruskal–Wallis test with post hoc pairwise comparisons. Bonferroni or Benjamini–Hochberg correction was used to account for multiple comparisons. The Benjamini–Hochberg method is a common alternative to the over-conservative Bonferroni correction, which often leads to missed findings [26]. Kendall’s correlation was used to examine the relationships between discrete variables. All p-values were two-sided; the significance threshold was set at p ≤ 0.05.

3. Results

3.1. Descriptive Data

A total of 207 records of patients who received complete maxillary and mandibular dentures from 2011 to 2014 were found and assessed. Based on the exclusion criteria, 43 records were eliminated. The remaining 164 records, including 90 (54.9%) female and 74 (45.1%) male patients, were used for the data analyses below. The subjects had a mean age of 68.0 years (SD = 11.8) with a maximum of 91 years and a minimum of 35 years, and 110 (67.1%) of them were above the age of 65.

The reasons for attendance in descending order were old/worn denture (40.9%); poor-quality denture (25.6%); miscellaneous (16.5%); and lack/loss of teeth (15.9%). There were 144 (87.8%) patients presented as edentulous, while 20 (12.2%) patients needed extraction prior to fabrication of new dentures. Regarding the identities of the operators, 121 (73.8%) patients were treated by students and 43 (26.2%) patients were treated by professionals.

3.2. Number of Appointments for Fabrication

The mean number of appointments taken for the fabrication of complete dentures for all 164 patients was 6.5 (SD = 1.6) with a minimum of 4 and a maximum of 12. The relationship between age and the number of appointments for fabrication was investigated using Kendall’s correlation. There was no correlation between age and the number of appointments for fabrication (τ_b = 0.010, p = 0.869).

The differences in the number of appointments were compared between females and males and between students and professionals using a Mann–Whitney test (

Table 2. The number of appointments taken for the fabrication of complete dentures according to patient gender and operator fabricating dentures.

		Mean ± SD	Min.	Max.	Significance
Patient gender	Female	6.8 ± 1.8 1	4	12	0.025 1
	Male	6.2 ± 1.3 1	4	10
Operator identity	Student	6.7 ± 1.7 2	4	12	0.015 2
	Professional	6.0 ± 1.1 2	4	9
Total		6.5 ± 1.6	4	12

¹ The number of appointments taken for females was significantly higher than that taken for males (p = 0.025; Mann–Whitney test with Bonferroni correction). ² The number of appointments taken by students was significantly higher than that taken by professionals (p = 0.015; Mann–Whitney test with Bonferroni correction).

). As two hypotheses were tested simultaneously, a Bonferroni-adjusted significance level of 0.025 was used. For the 90 female patients, the mean was 6.8 (SD = 1.8) with a minimum of 4 and a maximum of 12. For the 74 male patients, the mean was 6.2 (SD = 1.3) with a minimum of 4 and a maximum of 10. Female patients had significantly more appointments than male patients (p = 0.025). On the other hand, for the 121 patients treated by students, the mean was 6.7 (SD = 1.7) with a minimum of 4 and a maximum of 12. For the 43 patients treated by professionals, the mean was 6.0 (SD = 1.1) with a minimum of 4 and a maximum of 9. Students completed significantly more appointments than professionals (p = 0.015).

3.3. Number of Appointments for Adjustment

The mean value of the number of appointments for adjustment for all 164 patients was 3.6 (SD = 2.8) with a minimum of 0 and a maximum of 18. The relationship between age and the number of review appointments was examined using Kendall’s correlation. There was a significant positive correlation between age and the number of review appointments (τ_b = 0.167, p = 0.003). The differences in the number of review appointments were compared between females and males and between students and professionals using a Mann–Whitney test (Table S1). No significant difference in the number of review appointments was found between female and male patients or between student and professional operators.

The mean numbers of review appointments at 0 to 3 months, 3 to 12 months, 12 to 24 months, 24 to 60 months, and over 60 months were 2.8 (SD = 1.9), 0.4 (SD = 1.0), 0.2 (SD = 1.0), 0.1 (SD = 0.7), and 0.1 (SD = 0.2), respectively (Table S2). According to the Kruskal–Wallis test, there was a significant difference in means among the five different time intervals (H = 516.535, p = 0.000). The post hoc pairwise comparison showed that the number of appointments for adjustment at 0 to 3 months was significantly higher than that at 3 to 12 months (p = 0.000), 12 to 24 months (p = 0.000), 24 to 60 months (p = 0.000), and over 60 months (p = 0.000); no significant difference was found among the latter four groups. Also, approximately 50% of subjects completed their post-insertion appointments for adjustment within eight weeks (Figure S1).

3.4. Post-Insertion Complications and Events

Among all the 164 subjects who received both maxillary and mandibular complete dentures, 54 (32.9%), 26 (15.9%), 28 (17.1%), and 8 (4.9%) experienced post-insertion pain, a retention/stability issue, an occlusion issue, and an aesthetic issue in the maxilla, respectively; 96 (58.5%), 40 (24.4%), 38 (23.2%), and 7 (4.3%) experienced post-insertion pain, a retention/stability issue, an occlusion issue, and an aesthetic issue in the mandible, respectively (

Table 3. The differences in the incidences of post-insertion complications of maxillary and mandibular complete dentures.

Post-Insertion Complication		Frequency (Percentage)		Chi-Square Value	Significance
		Maxilla	Mandible
Pain	Present	54 (32.9%)	96 (58.5%)	21.670	0.000 1
	Absent	110 (67.1%)	68 (41.5%)
Retention/stability issue	Present	26 (15.9%)	40 (24.4%)	3.718	0.054
	Absent	138 (84.1%)	124 (75.6%)
Occlusion issue	Present	28 (17.1%)	38 (23.2%)	1.897	0.168
	Absent	136 (82.9%)	126 (76.8%)
Aesthetic issue	Present	8 (4.9%)	7 (4.3%)	0.070	0.792
	Absent	156 (95.1%)	157 (95.7%)

¹ Mandibular complete denture was significantly more associated with pain than maxillary complete denture (χ² = 21.670, df = 1, p = 0.000; Chi-square test with Bonferroni correction).

). The differences in the incidences of the four types of post-insertion complications between the maxilla and mandible were compared using a Chi-square test. As four hypotheses were tested simultaneously, a Bonferroni-adjusted significance level of 0.0125 was used. The mandible was significantly more associated with post-insertion pain than the maxilla (χ² = 21.670, df = 1, p = 0.000). No significant difference was found in the other three post-insertion complications.

Among the 121 subjects treated by students, 90 (74.4%) experienced post-insertion pain, 36 (29.8%) experienced retention/stability issues, 37 (30.6%) experienced occlusion issues, and 6 (5.0%) experienced aesthetic issues. Among the 43 subjects treated by professionals, 23 (53.5%) experienced post-insertion pain, 12 (27.9%) experienced retention/stability issues, 36 (83.7%) experienced occlusion issues, and 2 (4.7%) experienced aesthetic issues (Table S3). The relationships between the incidences of the four post-insertion complications and operator identity were examined using a Chi-square test. As four hypotheses were tested simultaneously, a Bonferroni-adjusted significance level of 0.0125 was used. Post-insertion pain was significantly more associated with student operators than the professionals (χ² = 6.462, df = 1, p = 0.011). No significant difference was found in the other three post-insertion complications.

Regarding post-insertion events, the incidences of relines, denture base fractures, loss of artificial teeth, and replacement of dentures for the maxilla were 10 (6.1%), 0, 1 (0.6%), and 20 (12.2%), respectively; the incidences of relines, denture base fractures, loss of artificial teeth, and replacement of dentures for the mandible were 20 (16.5%), 2 (1.2%), 2 (1.2%), and 21 (12.8%), respectively (

Table 4. The differences in the incidences of post-insertion events of maxillary and mandibular complete dentures.

Post-Insertion Event		Frequency (Percentage)		Chi-Square Value	Significance
		Maxilla	Mandible
Reline	Present	10 (6.1%)	27 (16.5%)	8.804	0.003 1
	Absent	154 (93.9%)	137 (83.5%)
Denture base fracture	Present	0	2 (1.2%)	2.012	0.156
	Absent	164 (100%)	162 (98.8%)
Loss of artificial teeth	Present	1 (0.6%)	2 (1.2%)	0.336	0.562
	Absent	163 (99.4%)	162 (98.8%)
Replacement of denture	Present	20 (12.2%)	21 (12.8%)	0.028	0.867
	Absent	144 (87.8%)	143 (87.2%)

¹ Mandibular complete denture was significantly more associated with post-insertion reline than maxillary complete denture (χ² = 8.804, df = 1, p = 0.003; Chi-square test with Bonferroni correction).

). The differences in the incidences of the four types of post-insertion events between the maxilla and mandible were compared using a Chi-square test. As four hypotheses were tested simultaneously, a Bonferroni-adjusted significance level of 0.0125 was used. The mandible was significantly more associated with post-insertion reline than the maxilla (χ² = 8.804, df = 1, p = 0.003). No significant difference was found in the other three post-insertion events. The relationships between the incidences of the four post-insertion events and operator identity were also examined using a Chi-square test, and no significant difference was found.

3.5. Patient Satisfaction

Among the total of 164 patients, 67 (40.9%) were satisfied, 53 (32.3%) were dissatisfied, and 44 (26.8%) were undocumented. The undocumented subjects were excluded from the analyses regarding patient satisfaction. The differences in age, number of appointments for fabrication, and number of review appointments between the satisfied patients and the dissatisfied were compared using a Mann–Whitney test (

Table 5. The differences in age, number of appointments for fabrication, and number of appointments for adjustment between the satisfied patients and the dissatisfied.

	Patient Satisfaction	Mean ± SD	Min.	Max.	Significance
Age	Satisfied	66.2 ± 12.6	36	90	p = 0.023 1
	Dissatisfied	70.9 ± 11.0	36	91
Number of appointments for fabrication	Satisfied	6.4 ± 1.3	5	10	p = 0.667
	Dissatisfied	6.7 ± 1.8	4	12
Number of appointments for adjustment	Satisfied	3.1 ± 2.1	1	11	p = 0.001 2
	Dissatisfied	4.9 ± 3.5	0	18

¹ The dissatisfied patients had significantly higher age than the satisfied patients (p = 0.023; Mann–Whitney test with Benjamini–Hochberg correction). ² The dissatisfied patients had significantly higher number of review appointments than the satisfied patients (p = 0.001; Mann–Whitney test with Bonferroni corrections).

). As three hypotheses were tested simultaneously, a multiple-comparison post hoc correction was required. The Bonferroni-adjusted significance level was 0.0167. The Benjamini–Hochberg-adjusted significance levels at the false discovery rate of 5% for number of review appointments, age, and number of appointments for fabrication were 0.0167, 0.0333, and 0.05, respectively. First, the mean age of the satisfied patients was 66.2 (SD = 12.6), while the mean of the dissatisfied was 70.9 (SD = 11.0); the dissatisfied patients had significantly higher age than the satisfied patients (p = 0.023) according to the Benjamini–Hochberg correction. Second, the mean number of appointments for fabrication of the satisfied patients was 6.4 (SD = 1.3), while the mean of the dissatisfied was 6.7 (SD = 1.8); no significant difference was observed. Lastly, the mean number of review appointments of the satisfied patients was 3.1 (SD = 2.1), ranging from 1 to 11, while the mean of the dissatisfied was 4.9 (SD = 3.5), ranging from 0 to 18; the dissatisfied patients had a significantly higher number of review appointments than the satisfied patients (p = 0.001).

The relationships between patient satisfaction and patient gender, reason for attendance (including lack/loss of teeth, old/worn denture, and poor-quality denture), presenting clinical status, operator fabricating dentures, post-insertion complication (pain, retention/stability, occlusion, and aesthetics), and post-insertion event (reline, denture base fracture, loss of artificial teeth, and replacement of denture) were examined using a Chi-square test (

Table 6. The relationships between patient satisfaction and patient gender, reason for attendance, presenting clinical status, operator fabricating dentures, post-insertion complication, and post-insertion event.

		Patient Satisfaction		Chi-Square Value	Significance
		Satisfied	Dissatisfied
Patient gender	Female	42 (63.6%)	24 (36.4%)	3.621	0.057
	Male	25 (46.3%)	29 (53.7%)
Reason for attendance	Lack/loss of teeth	11 (52.4%)	10 (47.6%)	0.123	0.726
	Other reasons	56 (56.6%)	43 (43.4%)
	Old/worn denture	35 (72.9%)	13 (27.1%)	9.468	0.002 1
	Other reasons	32 (44.4%)	40 (55.6%)
	Poor-quality denture	13 (43.3%)	17 (56.7%)	2.534	0.111
	Other reasons	54 (60.0%)	36 (40.0%)
Presenting clinical status	Edentulous	59 (57.8%)	43 (42.2%)	1.114	0.291
	Extraction needed	8 (44.4%)	10 (55.6%)
Operator identity	Student	52 (55.9%)	41 (44.1%)	0.001	0.974
	Professional	15 (55.6%)	12 (44.4%)
Post-insertion complication	Pain	47 (52.8%)	42 (47.2%)	1.278	0.258
	No pain	20 (64.5%)	11 (35.5%)
	Retention/stability issue	4 (11.1%)	32 (88.9%)	41.712	0.000 2
	No retention/stability issue	63 (75.0%)	21 (25.0%)
	Occlusion issue	21 (60.0%)	14 (40.0%)	0.348	0.555
	No occlusion issue	46 (54.1%)	39 (45.9%)
	Aesthetic issue	1 (14.3%)	6 (85.7%)	5.204	0.023
	No aesthetic issue	66 (58.4%)	47 (41.6%)
Post-insertion event	Reline	2 (8.0%)	23 (92.0%)	29.300	0.000 3
	No reline	65 (68.4%)	30 (31.6%)
	Denture base fracture	0	2 (100%)	2.571	0.109
	No denture base fracture	67 (56.8%)	51 (43.2%)
	Loss of artificial teeth	2 (100%)	0	1.609	0.205
	No loss of artificial teeth	65 (55.1%)	53 (44.9%)
	Replacement of denture	4 (19.0%)	17 (81.0%)	13.968	0.000 4
	No replacement of denture	63 (63.6%)	36 (36.4%)

¹ Attendance with old/worn dentures was significantly more associated with patient satisfaction than dissatisfaction (χ² = 9.468, df = 1, p = 0.002; Chi-square test with Bonferroni correction). ² The presence of retention/stability issues was significantly more associated with patient dissatisfaction than satisfaction (χ² = 41.712, df = 1, p = 0.000; Chi-square test with Bonferroni correction). ³ The incidence of post-insertion relines was significantly more associated with patient dissatisfaction than satisfaction (χ² = 29.300, df = 1, p = 0.000; Chi-square test with Bonferroni correction). ⁴ The incidence of replacement of dentures was significantly more associated with patient dissatisfaction than satisfaction (χ² = 13.968, df = 1, p = 0.000; Chi-square test with Bonferroni correction).

). As 14 hypotheses were tested simultaneously, a Bonferroni-adjusted significance level of 0.0036 was used. Attendance with old/worn dentures was significantly more associated with patient satisfaction than the dissatisfaction (χ² = 9.468, df = 1, p = 0.002). The incidences of retention/stability issues (χ² = 41.712, df = 1, p = 0.000), relines (χ² = 29.300, df = 1, p = 0.000), and replacement of dentures (χ² = 13.968, df = 1, p = 0.000) were significantly more associated with patient dissatisfaction than satisfaction. All other variables were not significantly related to patient satisfaction or dissatisfaction.

4. Discussion

This study sample of patients who received both maxillary and mandibular complete dentures comprised 54.9% females and 45.1% males. This tendency of females being slightly more than males was in accordance with many previous studies of patients who used complete dentures on either one or both arches [6,14,15,25,27]. It has also been reported that edentulism could be more prevalent in females than in males [4,9]. The mean age of 68.0 ± 11.8 years and the minimum age of as young as 35 years were also close to results of some previous studies [21,23]. The need for replacement of old/worn dentures (40.9%) was the most common reason for attendance.

The mean number of appointments for fabrication was 6.5 ± 1.6, slightly more than the typical five appointments in theory [12]. The minimum number of appointments was four, matching what can be achieved by combining the final impression and jaw registration steps on one appointment [28]. Female patients (6.8 ± 1.8) took statistically more appointments than male patients (6.2 ± 1.3; p = 0.025), which may be explained by their tendency of being more sensitive to discomfort or pain and aesthetics [29,30]. Student operators (6.7 ± 1.7) took statistically more appointments than professional operators (6.0 ± 1.1; p = 0.015), which can be explained by their different levels of experience. However, considering the small differences between the means and the sizes of standard deviations, these differences may not be clinically significant.

The number of appointments for adjustments was 3.6 ± 2.8 on average, but the maximum reached as many as 18. It was found here that increased patient age was significantly associated with more review appointments (τ_b = 0.167, p = 0.003). This is in accordance with the previous knowledge that older patients take longer to adapt to new dentures [6,31]. Additionally, most patients (93.9%) presented at least once for adjustments during the first three months post-insertion, while this sharply declined to 14.0% between three and twelve months. After eight weeks, approximately 50% of subjects had not returned for further adjustments. The mean number of appointments for adjustments was significantly reduced after the first three months (p = 0.000) from 2.8 ± 1.9 to 0.4 ± 1.0. This agrees with the results of Hsu et al., which showed that the first three months was the period of the most frequent review visits [28]. Other studies emphasised even earlier adjustments; Kivovics et al. found that over 87% of dentures needed adjustments by week one [32]. The first three months post-insertion has also been found to have the highest likelihood for the discontinuation of denture wearing, mostly due to trauma on the subjacent mucosa or lack of retention [15]. This early period of adaptation has an important influence on patients’ long-term perception of complete denture treatment success [13,15]. Hence, it is important that clinicians take the responsibility to organise review appointments until patients have adapted to their new dentures.

In this study, post-insertion pain was by far the most frequent complication in both the maxilla (32.9%) and mandible (58.5%). Retention/stability issues and occlusion issues followed after with similar occurrences to each other. In comparison, Bilhan et al. found loss of retention and irritation or ulceration as the two most frequent complications [14]. Meanwhile, student operators (74.4%) were significantly more associated with post-insertion pain than professionals (53.5%; p = 0.011). The students might have been more diligent in documenting the details of patient response due to close supervision, potentially contributing to this disparity in part.

The occurrence of post-insertion pain was strongly significantly higher in the mandible than the maxilla (χ² = 21.670, p = 0.000). Similarly, the incidence of post-insertion reline was also significantly higher in the mandible (16.5%) than the maxilla (6.1%; χ² = 8.804, p = 0.003). Previous studies have found that mandibular dentures presented with more ulcerative lesions and problems with retention and adaptation compared to maxillary dentures [15,32,33]. Meanwhile, other studies have identified having a clinically stable mandibular denture as the most important determinant of patient satisfaction [25,27,34]. Thus, careful attention should be paid to the final impression taking and border moulding as well as the adaptation of denture and proper extension of flanges for the fabrication of mandibular complete dentures [33]. The results of this study support the McGill consensus statement and the York consensus statement that both supported the use of implant overdenture as the first choice of treatment for edentulous mandibles rather than conventional dentures [35,36]. Admittedly, this is limited by various other factors, including patient age, psychological condition, aesthetic needs, hygiene access, ridge resorption, inter-occlusal space, medical comorbidities, and, importantly, the financial cost of the implants [8].

Analyses on patient satisfaction revealed its relationship with several factors. First, a significantly higher number of appointments for adjustment was observed in patients with dissatisfaction (4.9 ± 3.5) than those with satisfaction (3.1 ± 2.1; p = 0.001). This is in accordance with the negative correlations between phonetics satisfaction and the number of post-insertion adjustments found by Gaspar et al. and between chewing satisfaction and the number of post-insertion adjustments found by Santos et al. [23,37]. Second, dissatisfied patients (70.9 ± 11.0) were significantly older than satisfied patients (66.2 ± 12.6; p = 0.023). This may be explained by the aforementioned fact that older patients take longer to adapt to new dentures [6,31]. Third, the attendance to the clinic due to old/worn dentures (72.9%) was significantly associated with satisfaction in contrast to the attendance due to other reasons (χ² = 9.468, p = 0.002). This observation indicates that previous success in complete denture treatment may be considered as a predictor of future success. Having old/worn dentures without any other complaints may mean that these patients were experiencing complete denture wears with adequate adaption, realistic expectation, and stable residual ridge form, potentially contributing to their satisfaction on new complete dentures. It has been previously reported that around 60% of experienced denture wearers were satisfied with eating and speaking functions of their new dentures within one week [38]. A later study revealed that previous denture experience had a significant positive correlation with the overall efficacy and a significant negative correlation with difficulty in food-chewing [39]. Furthermore, patients with post-insertion retention/stability issues (88.9%) were significantly more associated with dissatisfaction than those without (25.0%; χ² = 41.712, p = 0.000). Similarly, those who had post-insertion reline (92.0%), a main intervention to address retention/stability issues, were significantly more associated with dissatisfaction than others (31.6%; χ² = 29.300, p = 0.000). These observations are in accordance with the findings of Alfadda et al. and Yamaga et al., who suggested that mandibular denture retention and stability were major influencing factors of patient satisfaction [25,27]. It has been suggested that an adequate mandibular ridge form allows for accurate recording of jaw relation and leads to improved satisfaction [27]. Lastly, the incidence of post-insertion denture replacement (81.5%) was significantly more associated with patient dissatisfaction than the non-incidence (36.4%; χ² = 13.968, p = 0.000). It would be reasonable that patients were not satisfied when post-insertion issues became serious enough to require replacement.

In contrary, several factors not found to be associated with patient satisfaction are noteworthy. First, although it was not statistically significant, there was a tendency that more female patients (63.6%) than male (46.3%) were satisfied (p = 0.057). According to Santos et al., women presented a higher satisfaction score for aesthetics than men [23]. Combined with the aforementioned observation that females took statistically more appointments for fabrication than males, it might be possible that females tend to be more careful during denture fabrication so that they are more likely to be satisfied after insertion. Also, patient satisfaction did not differ between student operators (55.9%) and professional operators (55.6%; p = 0.974), although students statistically completed more appointments for fabrication and were associated with more post-insertion pain. In contrast, Kimoto et al. found that as compared to patients treated by dentists with less than three years of prosthodontic experience, those treated by dentists with over 10 years of experience had higher satisfaction in general and in speaking, stability, and retention [24]. Again, students in this present study might have improved patient satisfaction through extra caution during denture fabrication and patience in communication. Lastly, the incidence (60.0%) or non-incidence of occlusion issues (54.1%) did not impact patient satisfaction (p = 0.555), in accordance with the results of Alfadda et al. and Bilhan et al. [6,25].

This study is subject to some limitations due to the data source. First, all the records were obtained in a university setting. The majority of the patients were treated by undergraduate dentistry students under supervision. Many patients were under government pension for the aged population, as they were eligible for free treatment at the university clinic. Thus, there may be potential bias in applying findings of this study to complete dentures fabricated at private dental practices. Second, this study did not analyse the actual usage of the complete dentures after insertion and its relationship with quality of life. This was inevitable as these questions were not a part of the standard practice at the university clinic and such information could not be collected retrospectively. Similarly, the analysis did not consider patients’ mental and emotional status due to the same reason.

5. Conclusions

The retrospective analysis of clinical records of 164 patients who received both complete maxillary and mandibular dentures at an Australian university teaching clinic revealed the following:

• The average number of appointments for adjustments was 2.8 ± 1.9 during the first three months post-insertion after which this sharply declined to 0.4 ± 1.0, and approximately 50% of patients completed all their adjustments within the first eight weeks;
• Mandibular complete dentures were significantly more associated with post-insertion pain and post-insertion reline than maxillary complete dentures;
• Patient satisfaction was significantly related to the patient age, number of appointments for adjustment, attendance with old/worn dentures, presence of retention/stability issues, and incidences of post-insertion reline and denture replacement.
• These findings may advise dental clinicians of the contributing factors of common issues with complete dentures and assist them in meeting patient expectations. Future research directions may include similar analysis of clinical records at private dental practices and consideration of other factors such as denture usage and mental status.