Histologic evaluation of the effect of nicotine administration on bone regeneration. A study in dogs

COMPARATIVE ANALYSIS ON THE RESULT FOR ARTHROSCOPIC ROTATOR CUFF SUTURE BETWEEN SMOKING AND NON-SMOKING PATIENTS

Objective: To comparatively analyze the results from arthroscopic rotator cuff suture between smoking and non-smoking patients. Methods: A group of 286 patients who underwent arthroscopic suturing of primary rotator cuff injuries between June 12, 2002, and May 14, 2008, was analyzed. The patients included in the study were evaluated using the UCLA scale, with a minimum follow-up of 12 months and average of 56.52 months. The variables studied were age, sex, side operated, dominance, profile of cigarette use and UCLA index. Results: This study evaluated a total of 205 patients. Mean age (p = 0.289) and sex (p = 0.124) were analyzed statistically between the smoking and non-smoking patients and the two groups were considered to be similar. The average UCLA score for the non-smoking patients (143) was 34 (32 to 35). The average UCLA score for the smoking patients (51) was 33 (29 to 35). There was no statistically significant difference in UCLA score (p = 0.123) between the smoking and non-smoking patients. For the purposes of statistical analysis, we grouped the small and medium tears (107) and compared these with the large and extensive tears (80), between smokers and non-smokers. There was no statistically significant difference using the Mann-Whitney test regarding the small and medium tears (p = 818). There was a statistically significant difference using the Mann-Whitney test regarding the large and extended tears, between the smoking and non-smoking patients, such that the non-smokers showed better UCLA scores (p = 0.038). Conclusion: The results from arthroscopic suturing of large and extensive rotator cuff injuries are inferior among smoking patients.

Nicotine effect on bone remodeling during orthodontic tooth movement: histological study in rats

INTRODUCTION

Nicotine is harmful to angiogenesis, osteogenesis and synthesis of collagen.

OBJECTIVE

The aim of this study was to investigate the effect of nicotine on bone remodeling during orthodontic movement in rats.

METHODS

Eighty male Wistar rats were randomly divided into three groups: Group C (control), group CM (with orthodontic movement) and group NM (nicotine with orthodontic movement) groups. The animals comprising groups C and CM received 0.9% saline solution while group NM received nicotine solution (2 mg/kg). A nickel-titanium closed-coil spring was used to induce tooth movement. The animals were euthanized and tissue specimens were histologically processed. Blood vessels, Howship's lacunae and osteoclast-like cells present in the tension and compression areas of periodontal ligaments were quantified. The extent of bone formation was evaluated under polarized light, to determine the percentage of immature/mature collagen.

RESULTS

It was observed lower blood vessel densities in the NM group in comparison to the CM group, three (p < 0.001) and seven (p < 0.05) days after force application. Osteoclast-like cells and Howship's lacunae in the NM group presented lower levels of expression, in comparison to the CM group, with significant differences on day 7 (p < 0.05 for both variables) and day 14 (p < 0.05 for osteoclast-like cells and p < 0.01 for Howship's lacunae). The percentage of immature collagen was increased in the NM group in comparison to the CM group, with a statistically significant difference on day 3 (p < 0.05), day 7 (p < 0.001), day 14 (p < 0.001) and day 21 (p < 0.001).

CONCLUSIONS

Nicotine affects bone remodeling during orthodontic movement, reducing angiogenesis, osteoclast-like cells and Howship's lacunae, thereby delaying the collagen maturation process in new bone matrix.

The in vitro and in vivo effects of nicotine on bone, bone cells and fracture repair

INTRODUCTION

Cigarette smoke has negative effects on bone metabolism and fracture repair. However, no study has reviewed effects of nicotine on bone and fracture repair independent of other constituents of cigarette smoke. The authors review the existing evidence of the effect of nicotine on 'bone' and 'bone cells' and fracture repair, drawing conclusions relevant to clinical practice and future research.

AREAS COVERED

A literature review was conducted using PRISMA guidelines and PubMed, Cochrane, MEDLINE/OVID, EMBASE, NHS Evidence and Google scholar databases. Articles were included if they specifically investigated the effects of nicotine on 'bone' or fracture repair in animal or human models or in vitro effects on 'bone cells'. A total of 64 papers were included in this review, of which 15 were human in vitro studies and 49 animal studies wherein 9 were in vitro and 40 in vivo. In vivo studies of the effects of nicotine in animals demonstrated widespread effects on bone including osteoneogenesis, osseointegration, steady-state skeletal bone and genes and cytokines relevant to bone cell physiology and bone homeostasis. In these studies, nicotine's effects are predominately negative, inhibiting bone cell metabolism and fracture repair, whereas most in vitro studies reported biphasic responses in all bone cells except osteoclastic cells.

EXPERT OPINION

The review suggests that nicotine has effects on osteoneogenesis, osseointegration and steady-state skeletal bone in animal in vivo models, as well as effects on all 'bone cells', via several mechanisms in both animal and human cell in vitro studies. The effect of nicotine is dose-dependent, with higher concentrations having predominantly negative effects, whereas at low concentrations a stimulatory effect is seen. Stimulatory effects on certain cells may indicate a possible, limited therapeutic role; advice regarding smoking cessation perioperatively should remain due to the other harmful components of cigarette smoke, but there may be scope for allowing the use of nicotine patches instead of complete abstention. Further research into clinical outcomes is required before the exact response of bone and fracture repair in humans to nicotine is known.

Cardoso LA, Shibli JA. Impact of Smoking on Human Bone Apposition at Different Dental Implant Surfaces: A Histologic Study in Type IV Bone

Smoking has adverse effects on peri-implant bone healing and can cause bone loss around successfully integrated implants placed on type IV bone. This study evaluated the influence of implant surface topography of microimplants retrieved from posterior maxilla of smokers after 2 months of unloaded healing. Seven partially edentulous patients received 2 microimplants (machined and sandblasted acid-etched surface) each during conventional implant surgery. Histometric evaluation showed that the mean bone to implant contact was 10.40 ± 14.16% and 22.19 ± 14.68% to machined and sandblasted acid-etched surfaces, respectively (P &lt; .001). These data suggest that the sandblasted acid-etched surface presented better results than the machined surface after a short healing time in smokers.