Assessment of Prevalence and Causative Factors for Replacement of Composite and Amalgam Restorations: An Observational Study

ABSTRACT

Aim:

This study intends to evaluate the frequency and causes of replacement for failed amalgam and composite dental restorations.

Methodology:

A cross-sectional study comprising female patients with failed permanent composite and amalgam restorations aged 15–60 years old was carried out at the dental clinics of Qassim University. Using a self-structured proforma, demographic data and causes for restoration failure were recorded. The effectiveness of the restorations was assessed by using the Ryge criteria after performing clinical and radiographic examinations. The Statistical Package for Social Science was used for the statistical analysis.

Results:

It is found that 84.6% of the 299 unsuccessful restorations examined were composite, and 15.4% were amalgam. The main reason for dental failure for both amalgam (95.6%) and composite (93.28%) restorations was secondary caries. Failure of amalgam restoration was largely caused by poor marginal adaptation. With varied incidences between amalgam and composite restorations, typical complaints included discomfort, sensitivity, pain, and food impaction with soreness. The main justification for replacement in amalgam restorations was sensitivity. Repair and replacement rates were similar for amalgam, composite, and mandibular/maxillary restorations. Moreover, 21.1% of individuals overall reported no symptoms, with 8.7% in the amalgam group and 23.3% in the composite group with significant differences (χ² = 34.28, P = 0.001).

Conclusion:

According to the current study, secondary caries was found to be the main reason for both amalgam and composite restoration failure. The main problems reported were sensitivity, discomfort, and pain with amalgam showing more sensitivity-related failures.

INTRODUCTION

The primary purpose of the restorative procedure for a tooth with caries is to remove the carious lesion and improve the tooth’s morphology and function. The dental profession places a great deal of emphasis on dental restoration failure. It is common to measure survival and failure rates when evaluating clinical performance.[1] Moreover, determining the cause of restoration failure is essential because it helps to identify flaws in the tooth-restoration system.

Durability and longevity of dental restorations are attributed to variables such as the choice of restorative material, the technical proficiency of the restoration, and patient adherence to prescribed treatment.[2,3]

Class I and II posterior molars with cavities have been treated with composite and dental amalgam. Amalgam, a commonly used filling material in restorative dentistry, has a finite lifespan similar to other dental restorations. This material is preferred for its affordability, simplicity of administration, robustness, and longevity.[4] Although amalgam fillings offer advantages, their metallic appearance is not cosmetically appealing to dental practitioners and patients.[5] Therefore, restorative materials that match the natural color of teeth are favored for their aesthetic appeal.

In recent years, resin-based composites have replaced amalgam, which contains mercury and has been thoroughly investigated. The trend toward the less invasive management of dental caries and the improved physical and mechanical qualities of resin-based composite restorations have contributed to their increased use as posterior restorative materials.[6,7]

Disparities in the innate properties of teeth and restorative materials can lead to gaps at the tooth interface and restoration, resulting in marginal microleakage.[8] This phenomenon is acknowledged as the leading cause of failed dental composite restorations.[8] Marginal discoloration of the restoration, recurrent caries, lesions to the dentin-pulp complex, and marginal fractures characterize microleakage.[8]

Failure of dental restoration is a common phenomenon associated with a number of features. In a study, Massano et al. examined the durability of various nano-filled resin composites used for treating fractures and lesions in anterior teeth by using a direct method. During follow-up evaluations of 93 restorations in 53 individuals, no significant changes in color matching were observed until 96 months. However, weak restorations and fractures affected certain parameters.[9,10]

Several clinical trials have been conducted to assess the effectiveness of dental material in the posterior teeth. These studies have reported variable yearly failure rates ranging from 0% to 9.0%, with an average of 2.2%. Material failure rates are significantly comparable to those documented for amalgam, with failure rates varying from 0% to 7.4% with an average of 3%.[11]

Several factors have been linked to the failure of composite and amalgam restorations from a medical perspective. This study aimed to evaluate the prevalence and etiology of the replacement of composite and amalgam restorations due to failure.

METHODOLOGY

Study design and setting

It was a cross-sectional study conducted in the dental clinics of Qassim University.

Study participants

The current study included Saudi and non-Saudi female patients who presented to the female dental clinics of Qassim University, age ranging between 15 and 60 years, requiring replacement of one or more direct dental composite or amalgam restorations present in both anterior or the posterior teeth. Patients who refused to participate had poor oral hygiene, smoked, were immunocompromised, or had parafunctional habits were excluded from the study.

Sample size

With a margin of error of 5%, a confidence level of 95%, a population size of 1200, and a response distribution of 50%, the recommended sample size is 385. This means that a minimum sample size of 292 individuals from the population would provide accurate results within 5% with a confidence level of 95%.

Data collection procedure

Participants were randomly selected from the outpatient department of the female dental clinics at Qassim University under the supervision of clinical supervisors. Participants were provided with a thorough explanation of the research objectives, and informed consent was obtained from all study participants, with participant confidentiality guaranteed. A self-structured proforma was developed to record demographic information and reasons for composite and amalgam restoration failure. The patient had clinical and radiographic examination after prophylaxis and drying. Restoration efficacy was assessed by using Ryge criteria[12] and the proforma was filled out with all the findings.

Data analysis

The Statistical Package for Social Science was used for statistical analysis. Descriptive statistics were used to analyze demographic characteristics, while the Chi-square test was used for categorical variables.

Ethical consideration

This study was approved by the Ethics Committee of Qassim University (EA/6144/2021).

RESULTS

In this study, 299 failed restorations were evaluated; 15.4% (n = 46) of these restorations were of amalgam, while 84.6% (n = 253) were composite. Class I restorations were the most common (n = 145) followed by class III (n = 80).

Regarding the maxillary arch, a total of 169 restorations were observed, with 18 amalgams and 151 composites. Out of 130 restorations on the mandibular arch, 28 were amalgam restorations, and 102 were composite restorations [Table 1].

Table 1.

Characteristics and distribution of failed dental restorations

	Variable	Amalgam (n=46, 15.4%)	Composite n=253, 84.6%)	Total 299
Class	Class 1	29	116	145
	Class II	17	42	59
	Class III	0	80	80
	Class V	0	17	17
Arch	Maxilla	18	151	169
	Mandible	28	102	130
Teeth	Anterior	0	91	91
	Posterior	46	162	208
Duration	Up to 2 years	16	96	112
	More than 2 less than 4 years	10	111	121
	More than 4 years	20	46	66

Secondary caries was found to be the most common cause of failure. In amalgam, 95.65% (n = 44) and in composite 93.28% (n = 236) of the failures were observed due to secondary caries. No differences have been found in terms of material and secondary caries (χ² = 0.368, P = 0.544). In more than 50% of the amalgam restoration, marginal adaptation is the cause for failure [Table 2].

Table 2.

Reasons for failure of defective restorations

Reason of failure	Ryge scoring	Amalgam	Composite	χ2, P
Color match	A (alfa)	0	13	277.36, <0.001
	B (bravo)	0	237
	C (charlie)	46	3
Cavo-surface marginal discoloration	A (alfa)	1	5	6.54, 0.08
	B (bravo)	38	228
	c (charlie)	7	14
Anatomic form	A (alfa)	0	2	8.99, 0.02
	B (bravo)	25	180
	c (charlie)	21	71
Marginal adaptation	A (alfa)	0	2	26.71, <0.001
	B (bravo)	21	178
	c (charlie)	23	44
	D (delta)	2	29
Secondary caries	A (alfa)	2	17	0.368, 0.544
	B (bravo)	44	236

In 23.7% of all cases, discomfort was reported with a significantly lower incidence in the amalgam group (6.5%) compared to the composite group (26.9%). In 13.0% of cases, sensitivity was observed with a higher prevalence in the amalgam group (34.8%) than in the composite group (9.0%). Pain was reported in 15.7% of cases, with a greater incidence in the Amalgam group (26.1%) than in the composite group (13.8%). In total, 21.1% of participants reported no symptoms, with the incidence being lower in the amalgam group (8.7%) than in the composite group (23.3%). The difference is significant (χ² = 34.28, P < 0.001) [Table 3].

Table 3.

Symptoms associated with restorative materials amalgam and composite

Symptoms	Total	Amalgam	Composite	χ2, P
Discomfort	71 (23.7%)	3 (6.5%)	68 (26.9%)	34.28, P<0.001
Sensitivity	39 (13.0%)	16 (34.8%)	23 (9.1%)
Pain	47 (15.7%)	12 (26.1%	35 (13.8%)
Pain and food impaction	79 (26.4%)	11 (23.9%)	68 (26.9%)
None	63 (21.1%)	4 (8.7%)	59 (23.3%)

No significant difference has been observed in the repair and replacement status between amalgam and composite (χ² = 2.87, P = 0.09). Moreover, no significant difference has been observed in the repair and replacement status between mandibular and maxillary restorations (χ² = 0.078, P = 0.78) [Table 4].

Table 4.

Frequency of replacement in amalgam and composite and in maxilla and mandible

Status	Amalgam	Composite	χ2, P
Repair	0	15	2.87, 0.09
Replace	46	238
Total	46	253
Status	Maxilla	Mandible
Repair	9	6	0.078, 0.78
Replace	160	124
Total	169	130

We observed that 29 class 1 restorations were of amalgam and 116 were of composite. The amalgam group had 17 class II restorations, while the composite group had 42. The composite group had 80 class III and 17 class V restorations, whereas the amalgam group had none. Moreover, in maxilla, 18 amalgam fillings and 151 composite fillings were found. The mandible had 130 restorations in total including 28 amalgam and 102 composite [Figure 1].

Figure 1.

Number of teeth restored with composite versus amalgam in relation to the number of surfaces, tooth types, and dental arch

Table 5 shows a substantial correlation between restoration type (amalgam vs. composite) and oral cavity location (maxilla vs. mandible). Amalgam restorations were 39.1% and composite restorations were found to be 59.7% in the maxilla. However, in mandible, 60.9% were amalgam restorations and 40.3% were composite. A statistically significant difference is observed (χ² = 6.691, P = 0.01) [Table 5].

Table 5.

Distribution of amalgam and composite restoration according to the dental arch

Arch	Amalgam	Composite	Total	χ2, P
Maxilla	18 (39.1%)	151 (59.7%)	169 (56.5%)	6.691, P=0.01
Mandible	28 (60.9%)	102 (40.3%)	130 (43.5%)
Total	46 (15.4%)	253 (84.6%)	299 (100%)

DISCUSSION

The current study investigated the prevalence and etiology of the replacement of composite and amalgam restorations due to failure and observed that the principal reasons for the failure of composite restorations had been recognized to be a composite color alteration, secondary caries, and cavo-surface marginal discoloration. On the other hand, in the context of amalgam restorations, secondary caries and inadequate marginal adaptation were the most common cause of failure. Another study found that secondary caries was the primary reason for replacing the composite restoration.[13]

Microbiological variables may enhance secondary caries after composite restorations. The sensitivity of composite restorations to technique and the impact of oral hygiene on clinical outcomes must be stressed. Composites can cause secondary caries when paired with poor dental hygiene.[14,15]

Numerous factors, such as the curing process, storage conditions, chemical discoloration, and exposure to pigmented substances, can cause composite restorations to change color.[16] These color changes can occur progressively over time, necessitating restoration replacement.[17] Change in composite color is another rationale for replacement in this study. Patients increasingly choose restorations and composite resins with better color matching in dentistry.[18] As a result, it is imperative to attain precise color coordination with the adjacent teeth during the primary phase of treatment.[19] The durability and efficacy of composite restorations are contingent upon their capacity to sustain color stability throughout their lifespan. Therefore, maintaining color stability in composites throughout their usage is a vital factor in their choice.[20]

Our findings align with the previous study stating that secondary caries are the leading cause of failure in amalgam and resin composite restorations, particularly in permanent teeth.[21,22]

The current investigation analyzed the symptoms of discomfort of dental amalgam, which was determined to be sensitive. Furthermore, prevalent causes for replacement comprised discomfort and the presence of food debris leading to discomfort. A previous study also stated that the sensitivity in amalgam causes discomfort.[23]

Pain and food impaction are the leading cause of discomfort in both the restorations. Inadequate isolation and improper handling of materials can contribute to pain and food impaction.[24] Amalgam restorations require precise cavities and appropriate resistance and retention forms. Dental restoration failure can result from poor cavity design and amalgam management, causing pain, food impaction, secondary caries, or fractures.[25]

A subsequent study found that over 55% of restored amalgam restorations lasted over a decade, supporting our findings. Only 32% of replaced composite resin repairs lasted long. Despite conflicting research on dental repair endurance, most studies show that amalgam outlasts composite resin and fails less often. Our research matches these findings.[26]

The cross-sectional design is suitable for initial inquiry but limits causal associations between discovered components and restoration failure. Future longitudinal research should clarify temporal trends. The sample size followed the criteria, although a more diversified population might improve external validity. Additionally, patient-reported data may be subject to recall bias and interpretation problems. Future research should include objective clinical indicators like radiographic examinations to strengthen the study. These limitations highlight the need for further research, greater sample, and more objective clinical assessments in similar studies to better explain dental restoration failure and advise preventive actions.

CONCLUSION

In conclusion, secondary caries was the most common cause of failure in both amalgam and composite restorations. Sensitivity was the most prevalent complaint in amalgam. However, discomfort, pain, and food impactions were common causes of failure in composite restorations. Additionally, color alteration in composite restorations over time necessitated replacement for improved color matching with adjacent teeth. These findings offer valuable insights for dental practitioners in optimizing treatment approaches and patient care. Further studies and clinical interventions can contribute to addressing these challenges and improving the overall efficacy of dental restorations.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.