Comparative Evaluation of Marginal Bone Loss and Implant Failure Rate in Smokers and Nonsmokers

Abstract

Background:

Smoking impose various ill-effects on the alveolar bone concerning dental implants including reduced bone height, delayed healing of bone, poor peri-implant bone formation, increased bone loss, and peri-implantitis.

Aims:

The present clinical trial was aimed to analyze the smoking effect on dental implant survival rate as well as marginal bone loss in dental implants.

Materials and Methods:

Out of 86 patients, Group I had 43 patients who were smokers and Group II had nonsmokers. Following the implant placement, marginal bone loss radiographically and mobility were assessed clinically at 3, 6, and 12 months after implant loading.

Results:

The mean marginal loss seen in smokers at 3 months was 2.13 ± 0.21, 2.46 ± 0.09, 2.60 ± 0.0.92, and 2.74 ± 0.11 for maxillary anterior, maxillary posterior, mandibular anterior, and mandibular posterior regions, respectively. The 12-month recall visit showed a higher proportion of smokers having implant mobility. In smokers, 13.95% (n = 6) of the study participants had implant mobility, whereas 6.97% (n = 3) of the nonsmokers had mobility.

Conclusion:

Smoking is associated with long-term implant failure which is directly proportional to the duration ad frequency of smoking. Furthermore, smoking has a detrimental effect on dental implants and its surrounding bone.

INTRODUCTION

Loss of teeth eventually leads to compromised esthetics giving functional disability and incomplete smile appearance, which at last affects the life quality of patients. With the advancements in modern dentistry, using dental implants for replacing missing teeth has revolutionized treatment.[1] Using implant dentistry alleviates various problems associated with the restorative procedures for single as well as multiple teeth.[2]

In dental implants, the epithelial cells in the sulcular region are surrounded by the connective tissue above the bone.[3] The tissue stability is influenced via various cellular and molecular events.[4] Bone levels measured radiographically represent the most predictive clinical parameters of these molecular and cellular events.[5] Long-term implant survival depends largely on the surrounding bone due to its dynamic nature.[6]

Smoking imposes various ill-effects on the alveolar bone concerning dental implants including reduced bone height, delayed healing of bone, poor peri-implant bone formation, increased bone loss, and peri-implantitis.[7] Delayed failure of dental implants is highly linked with the habit of smoking, usually seen in the second implant surgical stage. Short implants placed in the maxilla are at additional risk for failure.[8,9] Implant failure is defined as the mobility of the implant during osseointegration or postoperative loading. Nicotine, which is the active ingredient, involved in smoking, suppresses blood circulation in the bones and inhibits the normal functions of the bone-forming cells.[10]

Although smoking and resulting biological complications lead to bone loss and hence the failure of dental implants, dental implants are widely used as a replacement for missing single and multiple teeth.[11] Irrespective of removable or fixed prosthesis given following implant placement, the marginal bone loss remains the most predictable parameter for assessing implant success/failure. Marginal bone loss of a maximum of 1 mm following the 1^st year of implant placement is considered successful about dental implants.[12]

Various studies in the literature list smoking as one of the most contributory factors leading to implant failure. The failure rate of 6.5%–20% is reported by different studies.[13,14] In areas with poor quality of the trabecular bone, a higher implant failure is seen in smokers.[15] This can be the reason for the higher failure rate in the maxilla and the least failure in the mandibular posterior region.[16] Failure can be attributed to the nicotine absorption in the bloodstream leading to vasoconstriction.[17]

The present clinical trial was aimed to analyze the smoking effect on dental implant survival rate as well as marginal bone loss in dental implants.

MATERIALS AND METHODS

The present clinical trial was conducted on 86 patients comprising both males and females with an age range of 22 years to 67 years, in whom the dental implants were placed between 2 years. The 86 patients were divided into equal two groups: Group I with smokers and Group II with nonsmokers. Demographic data and detailed smoking history were recorded from each of the patients. Those patients who were smoking more than 10 cigarettes in every 24 h for 2 years minimum were included in Group I like smokers.

The inclusion criteria for the study were patients who maintained good oral hygiene having a score of plaque index and gingival index ≤ 1, periodontally healthy and stable teeth at the adjacent site to implant placement, no smoking history (for Group II), and patients who smoked more than 10 cigarettes per day for 2 years at least (for Group I). The exclusion criteria for the study were patients having any systemic disease, a disease affecting the bone, medication affecting bone metabolism and function, poor oral hygiene, pregnant females, wasting disease, parafunctional habits, and periodontitis cases.

Plaque index scores were interpreted as follows: 0 = no plaque, 1 = plaque on the probe, 2 = plaque on the implant seen by the naked eye, and 3 = abundance of soft matter. The gingival index recorded the presence of bleeding and was scored as follows: 0 = no bleeding, 1 = isolated bleeding spots visible, 2 = blood forms a confluent red line along the margin, and 3 = heavy or profuse bleeding.

Implant location was considered as anterior if the implant was placed in the incisor or canine region, whereas the posterior site was considered for premolars and molars. Following the implant placement, the recall was scheduled at 3, 6, and 12 months after implant loading. The recall visit was focused on revaluation, data collection, motivation, and instruction regarding the successful plaque control measures and risk factors associated with implant failure.

To assess the smoking effect, radiographic bone loss was evaluated using the digital intraoral periapical radiographs by measuring the distance from the implant (widest part) to the crest of the alveolar bone mesially and distally. The difference in the parameters at each recall interval was examined and recorded. The recorded data for both the groups were statistically analyzed using one-way ANOVA keeping the level of significance at P ≤ 0.05.

RESULTS

The present study was carried out to evaluate the effect of smoking on the survival rate of dental implants and their surrounding bone loss. The recorded demographic characteristics are summarized in Table 1.

Table 1.

Demographic parameters and implant characteristics of study participants

Parameter	n (%)
Age	22–67
Gender
Male	49 (56.97)
Female	37 (43.02)
Smoking criteria
Smokers	43 (50)
Nonsmokers	45 (50)
Implant site
Maxillary anterior	21 (24.41)
Maxillary posterior	26 (30.23)
Mandibular anterior	15 (17.44)
Mandibular posterior	24 (27.90)

The crestal bone loss was evaluated on the digital intraoral periapical radiographs both on the mesial and distal sites of the implants. The mean values are depicted in Tables 2 and 3. Mobility in dental implants in both the groups is elaborated in Table 4.

Table 2.

Marginal bone loss at different time intervals in smokers

Implant placement site	3 months	6 months	12 months	P
Maxillary anterior	2.13±0.21	2.37±0.15	2.6±0.10	<0.00001
Maxillary posterior	2.46±0.09	2.73±0.10	3.23±0.11	<0.00001
Mandibular anterior	2.60±0.0.92	2.81±0.090	3.30±0.075	<0.00001
Mandibular posterior	2.74±0.11	2.66±0.116	3.20±0.093	<0.00001

Table 3.

Marginal bone loss at different time intervals in nonsmokers

Implant placement site	3 months	6 months	12 months	P
Maxillary anterior	1.17±0.095	1.30±0.14	1.48±0.12	<0.00001
Maxillary posterior	1.20±0.08	1.39±0.11	1.69±0.19	<0.00001
Mandibular anterior	1.34±0.129	1.79±0.165	2.0±0.453	<0.00001
Mandibular posterior	1.57±0.151	2.01±0.429	2.240.437	<0.00001

Table 4.

Mobility in dental implants in smokers and nonsmokers

Smoking	Parameters	n (%)	P
Subgroup	Smoker	6 (13.95)	?0.00001
	Nonsmoker	3 (6.97)
Frequency (cigarettes/day)	<20	1 (2.32)	<0.00001
	>20	8 (18.60)
Duration (years)	<5	2 (4.65)	<0.00001
	>5	11 (25.58)

DISCUSSION

Smoking leads to widespread systemic effects, which further initiates various mechanisms leading to impaired responses to implant treatment.[17] Various studies in the literature suggest a 1.69 times more implant mobility in smokers when compared to nonsmokers. These studies show smoking as an important risk factor for delayed implant failure.[4,18]

A study in literature by Deluca S in 2006 and Bain CA in 1993 has reported a significantly higher number of cases with peri-implantitis and implant failure in smokers. The findings of this study were consistent with the results presented, where a higher bone loss (marginal) was found in smokers at all the recall intervals.[19,20]

The present study was conducted to assess smoking effects on marginal bone loss and long-term implant survival. The present clinical trial showed a higher marginal bone loss in smokers with dental implants at all the recall intervals of 3, 6, and 12 months. The mean loss (marginal bone) seen in the present study with smokers at 3 months was 2.13 ± 0.21, 2.46 ± 0.09, 2.60 ± 0.0.92, and 2.74 ± 0.11 for maxillary anterior, maxillary posterior, mandibular anterior, and mandibular posterior regions, respectively. The mean bone loss at 12 months increased to 2.6 ± 0.10, 3.23 ± 0.11, 3.30 ± 0.075, and 3.20 ± 0.093, respectively; this difference was statistically significant with P ˂ 0.00001. The findings of the present study were consistent with the study by Barzanji SA et al. in 2018, Pereira ML et al. in 2008, Feloutzis A et al. in 2013, Kan JY et al. 1999 and Lindquist LW et al. in 1996,[21,22,23,24,25] all of which have reported a statistically significant increase in marginal bone loss in smokers, especially in heavy smokers. P value for these studies was < 0.01, 0.027, and < 0.01, respectively. All these values were lower concerning nonsmokers.

CONCLUSION

Despite smoking being not considered as an absolute contraindication for implant placement, smoking has a detrimental effect on bone loss around dental implants. Marginal bone loss is also higher in smokers as compared to nonsmokers. Hence, the smoker patients in whom dental implants are placed should be given proper education and motivation for smoking cessation for long-term implant survival.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.