Osseointegration of endosseous ceramic implants after postoperative low-power laser stimulation: an in vivo comparative study

Comparative Evaluation of Normal Saline Gel and Ozone Therapy on Soft and Hard Tissue Health in Dental Implant Surgery

AIMS

To comparatively evaluate the effect of normal saline gel and ozonated saline-ozonated gel (ozone therapy) on pain, inflammation, soft tissue, and crestal bone loss in dental implant surgery.

METHODS AND MATERIAL

Forty adult patients scheduled to undergo implant were randomized into two groups: Twenty patients (n = 20) received ozone therapy and controls (n = 20) received normal saline and gel during implant placement. Inflammation and pain were noted at days 1 and 7 and 3 month intervals by estimating C-reactive protein (CRP) levels and assessing visual analogue scale (VAS) scores. At 3 months, soft tissue outcomes were noted in terms of plaque index, gingival index, and pocket depth, while crestal bone loss was noted via a radiograph.

RESULTS

Mean CRP levels were significantly higher in the control group as compared to that in the case group on day 1 and day 7 follow-ups (P < 0.05). Mean VAS scores for pain were also lower in the case group as compared to the control group at all follow-ups, but the difference was significant statistically only at day 1 (P = 0.061). The plaque index was significantly lower in the case group as compared to the control group (P = 0.011) at final follow-up. No significant difference between two groups was observed for crestal bone loss.

CONCLUSIONS

Ozone therapy during implant placement was effective in reduction of pain, systemic inflammation, and plaque deposition in dental implant patients.

The current status of stimuli-responsive nanotechnologies on orthopedic titanium implant surfaces

With the continuous innovation and breakthrough of nanomedical technology, stimuli-responsive nanotechnology has been gradually applied to the surface modification of titanium implants to achieve brilliant antibacterial activity and promoted osteogenesis. Regarding to the different physiological and pathological microenvironment around implants before and after surgery, these surface nanomodifications are designed to respond to different stimuli and environmental changes in a timely, efficient, and specific way/manner. Here, we focus on the materials related to stimuli-responsive nanotechnology on titanium implant surface modification, including metals and their compounds, polymer materials and other materials. In addition, the mechanism of different response types is introduced according to different activation stimuli, including magnetic, electrical, photic, radio frequency and ultrasonic stimuli, pH and enzymatic stimuli (the internal stimuli). Meanwhile, the associated functions, potential applications and developing prospect were discussion.

Implementation of Low-Level Laser Therapy in Dentistry: A Review

A type of light therapy known as low-level laser therapy (LLLT) uses only one wavelength of light. Low-level lasers (LLL) do not have a warming effect on the tissues; instead, they have an effect called photobiostimulation. LLL do not evaporate the tissue. The use of LLL to manage a range of illnesses is known as LLLT. Helium-neon lasers are an illustration of an LLLT product. Gallium arsenide, the infrared semiconductor made of gallium aluminum arsenide, is also an example. The performance powers range from 50 to 500 mW with electromagnetic spectrum wavelengths in the red and near-infrared region spanning from 630 to 980 nm and pulsed or continuous-wave emission. In periodontics, LLLT has gained prominence for several applications, including wound healing and pain relief after non-surgical and surgical procedures.

An Evaluation of the Effects of Photobiomodulation Therapy on the Peri-Implant Bone Healing of Implants with Different Surfaces: An In Vivo Study

(1) Background: This study evaluates the effects of photobiomodulation (PBM) therapy on the peri-implant bone healing of implants with a machined surface (MS) and treated surface (TS). (2) Methods: Topographic characterization of the surfaces (scanning electron microscopy [SEM]- energy dispersive X-ray spectroscopy [EDX]) was performed before and after implant removal. Twenty rabbits were randomly divided into four groups: MS and TS groups (without PBM therapy) and LMS and LTS groups (with PBM therapy). After implant placement, the stability coefficient (ISQ) was measured. In the periods of 21 and 42 days, the ISQ was measured again, followed by biomechanical analysis. (3) Results: The surfaces of the TS implants showed topographic differences compared with MS implants. The ISQ values of the LMS were statistically significant when compared with those of the MS at 42 days (p < 0.001). The removal torque values of the LMS were statistically significant when compared with those of the MS at 21 days (p = 0.023) and 42 days (p = 0.023). For SEM, in general, the LMS, TS and LTS presented high bone tissue coverage when compared to MS. (4) Conclusions: The PBM therapy modulated the osseointegration process and was evidenced mainly on the machined surface.

The stability of implants and microbiological effects following photobiomodulation therapy with one-stage placement: A randomized, controlled, single-blinded, and split-mouth clinical study

BACKGROUND

Studies have reported a positive effect on bone healing and the elimination of microorganisms placed on the titanium implants, while others have not confirmed the positive photobiomodulation therapy (PBMT) effects on bone regeneration and bone structure around the implants.

PURPOSE

The aim of the present study was to address the following questions: Does PBMT improve implant stability and affect microbiota around dental implants in the early stage of osseointegration?

MATERIALS AND METHODS

This study was designed as randomized-controlled prospective, split mouth, single-blinded clinical trial. Implants were randomly divided into two groups and implants placed in the test group were treated with Gallium-aluminum-arsenide (GaAlAs) diode laser with PBMT immediately after surgery and for 15 days (n = 47). In the control group, implants were not irradiated(n = 46). The primary stability of the implants was measured by the Resonance frequency analysis (RFA) after insertion and the secondary stability values were recorded at 30th, 60th, and 90th days after surgery as implant stability quotient (ISQ). The hand-held RFA was held perpendicular to the jaw line as indicated by the manufacturer for buccal-lingual (BL), mesial-distal (MD), and lingual-buccal (LB) measurement and different measurements were analyzed as separately.

RESULTS

Significantly higher magnetic RFA values were achieved on the 90th day in all measurement sides for both groups. ISQ levels in groups at baseline and the day-30, 60, and 90. ISQ readings were not statistically significant between test and control groups for each time point. A statistically significant increase in ISQ reading for BL, MD, and LB dimensions in both groups was noted from baseline to the day-90 (P < .05).

CONCLUSION

It was concluded that PBMT did not have a clinically significant effect on implant stabilization, especially in terms of ISQ values at early alveolar bone healing term. Clinical trial number is NCT04495335.

Immunomodulatory activity seen as a result of photobiomodulation therapy in stimulated primary human fibroblasts

OBJECTIVE

Oral biofilms burden host responses by induction of inflammatory mediators, exacerbating periodontal inflammation. Photobiomodulation Therapy (PBMT) has been shown to decrease levels of pro-inflammatory cytokines and chemokines. However, optimal wavelengths and exposure doses have not been established. This study investigated the effects of PBMT on human periodontal ligament fibroblasts (hPDLFs) stimulated with inflammatory mediators (LPS, TNF-α, and IL-1β).

METHODS

Cytotoxic effects of laser wavelengths 660 nm and 810 nm were assessed by measuring their effects on cellular dehydrogenase activity. The study was expanded to include 980 nm, 660 nm + 810 nm, and 810 nm + 980 nm. P.g. LPS, TNF-α, and/or IL-1β were added one hour before irradiation, then exposed to laser irradiation to determine the most appropriate stimulus. The levels of INF-γ, IL-6, IL-8, IL-17A/F, and MCP-1 production in stimulated hPDLFs were measured and analyzed.

RESULTS

P.g. LPS was a poor stimulus for hPDLFs, while TNF-α and IL-1β significantly elevated the analytes. The 660 nm laser treatment induced pro-inflammatory cytokines when stimulated, while 810 nm exhibited significant suppression. IL-1β was the stimulus of choice and the 810 nm wavelength alone exhibited anti-inflammatory effects for all analytes except IL-8, while the 810 nm in combination with 660 nm and/or 980 nm exhibited effects similar to 810 nm alone.

CONCLUSIONS

The downregulation of inflammatory mediators by the combination or individual treatment with 810 nm wavelength shows promise for the management of periodontal inflammation. PBMT may lead to the development of a novel approach in the management of periodontal disease.

Adjunctive Use of Lasers in Peri-Implant Mucositis and Peri-Implantitis Treatment: A Systematic Review

BACKGROUND

The aim of this systematic review is to compare the effectiveness of lasers in the treatment of implant mucositis and peri-implantitis compared to conventional treatment (non-surgical or surgical: resective or regenerative).

METHODS

Sources of PubMed, Cochrane and Google Scholar search engines were used on articles published from 1997 to 2020 in English, with selected keyword criteria applied. Nine randomized controlled trials (RCTs) were selected.

RESULTS

All included studies were considered of "high quality" according to the quality assessment scale. The comparative assessment of the RCTs was done twice for each RCT based on the type of treatment and according to wavelength. There is strong scientific evidence that, regarding non-surgical treatment, adjunct laser application can provide better results only in the short term (three months). Regarding the surgical approach, the method of decontamination plays a subordinate role. All wavelengths/applications presented similar results.

CONCLUSION

Within the limitations of this study, the adjunctive use of lasers in the treatment of peri-implant inflammation is effective for up to three months; there is no strong evidence regarding the long term benefit compared to conventional treatment.

Photobiomodulation in Periodontology and Implant Dentistry: Part 2

(Part 1 of this article can be located at www.liebertpub.com/doi/10.1089/photob.2019.4710.) Objective: Finding evidence-based treatment strategies for low-level light therapy and the correct incorporation of these treatment methods in the clinical practice of periodontics. Background: Photobiomodulation has been shown to have biostimulatory, anti-inflammatory, and analgesic effects that can be beneficial in periodontal and dental implant treatment procedures. Methods: In this review, we have addressed some clinical questions regarding the potential clinical application of low-level light irradiation and its photobobiomodulatory effects in periodontology and implantology. The literature was searched for in vivo (animal or clinical) articles written in English in four electronic databases of PubMed, Scopus, Google Scholar, and Cochrane Library until April 2019. Only studies with low irradiation doses without any thermal effects used only for their photobiomodulatory purposes were included. Results: We were able to find relevant studies for all of our questions, and positive effects for the application of light therapy were reported in most of the studies. However, there is still a great deal of heterogeneity in terms of study designs and most importantly in light irradiation devices and the parameters used. Due to this issue, it was not possible to reach specific evidence-based irradiation protocols for the questions addressed in this review. Conclusions: Based on our search results, an obvious positive effect of low-level light therapy on stimulation of healing of periodontal soft and hard tissues and reduction of inflammation can be seen. Future well-designed randomized control studies with the same irradiation settings and systematic reviews evaluating the studies found on the questions mentioned are necessary to reach evidence-based recommendations.

Effect of Low-Level Laser Irradiation on Stability and Marginal Bone of Narrow Implants Retaining Overdentures in Moderately Controlled Diabetic Patients

The researchers investigated the influence of low-level laser irradiation (LLLI) on implant stability and marginal bone of small-diameter implants retaining mandibular overdentures in patients with moderately controlled diabetes. Twenty patients (mean age = 59.32 ± 4.1 years) with moderately controlled diabetes mellitus (glycated hemoglobin A1c [HbA1c] = 8.1%-10.0 %) were rehabilitated by maxillary and mandibular conventional dentures. Two small-diameter implants (3 × 12 mm) were inserted in the canine areas of the mandible and immediately loaded by mandibular dentures. In a split-mouth design, LLLI was applied to 1 of the 2 implants in a random order (study group [SG]); the other implant was left as a control (control group [CG]). For each patient, gallium aluminum-arsenide diode low-level laser (940-nm wavelength, 0.50 ± 2 mW output power, 0.004 cm² spot size; Epic, Biolase, Inc, San Clemente, Calif) was applied around each implant with total delivered energy of 90 J (equally divided by 6 irradiation points) in 3 sessions. The application was done immediately after implant insertion, 3 days and 1 week after surgery. Implant stability (measured by Periotest) and marginal bone loss (MBL; measured by cone beam computerized tomography) were evaluated at implant loading (T1), 6 months (T6), and 12 months (T12). One implant failed in the CG and no failures occurred in the SG, resulting in 95% and 100% survival rates, respectively. The SG recorded higher Periotest values than the CG at all observation times. However, the difference was significant (P = .039) at T6 only. The SG recorded lower MBL values than the CG. No difference in MBL was detected between groups or peri-implant sites (mesial, distal, buccal, and lingual) at T6 and T12. Within the limits of this study, LLLI had no effect on marginal bone around immediately loaded small-diameter implants retaining overdentures in patients with moderately controlled diabetes. However, it was beneficial in improving implant stability 6 months after overdenture insertion.

Comparison of effects of LLLT and LIPUS on fracture healing in animal models and patients: A systematic review

The aim of this paper is to study the in vivo potency of low-level laser therapy (LLLT) and low intensity pulsed ultrasound (LIPUS) alone, accompanied by bone grafts, or accompanied by other factors on fracture healing in animal models and patients. In this paper, we aim to systematically review the published scientific literature regarding the use of LLLT and LIPUS to accelerate fracture healing in animal models and patients. We searched the PubMed database for the terms LLLT or LIPUS and/or bone, and fracture. Our analysis also suggests that both LIPUS and LLLT may be beneficial to fracture healing in patients, and that LIPUS is more effective. These finding are of considerable importance in those treatments with a LIPUS, as a laser device may reduce healing time. The most clinically relevant impact of the LIPUS treatment could be a significant reduction in the proportion of patients who go on to develop a nonunion. If it is confirmed that the therapeutic influence is true and reliable, patients will obtain benefits from LIPUS and LLLT. Further clinical trials of high methodological quality are needed in order to determine the optimal role of LIPUS and LLLT in fracture healing in patients.

The efficacy of low-level 940 nm laser therapy with different energy intensities on bone healing

The aim of this study was to evaluate the efficacy of low-level 940 nm laser therapy with energy intensities of 5, 10 and 20 J/cm2 on bone healing in an animal model. A total of 48 female adult Wistar rats underwent surgery to create bone defects in the right tibias. Low-level laser therapy (LLLT) was applied immediately after surgery and on post-operative days 2, 4, 6, 8, 10 and 12 in three study groups with energy intensities of 5 J/cm2, 10 J/cm2 and 20 J/cm2 using a 940 nm Gallium-Aluminium-Arsenide (Ga-Al-As) laser, while one control group underwent only the tibia defect surgery. All animals were sacrificed 4 or 8 weeks post-surgery. Fibroblasts, osteoblasts, osteocytes, osteoclasts and newly formed vessels were evaluated by a histological examination. No significant change was observed in the number of osteocytes, osteoblasts, osteoclasts and newly formed vessels at either time period across all laser groups. Although LLLT with the 10 J/cm2 energy density increased fibroblast activity at the 4th week in comparison with the 5 and 20 J/cm2 groups, no significant change was observed between the laser groups and the control group. These results indicate that low-level 940 nm laser with different energy intensities may not have marked effects on the bone healing process in both phases of bone formation.

Low-level laser therapy affects osseointegration in titanium implants: resonance frequency, removal torque, and histomorphometric analysis in rabbits

Objectives

The purpose of this study was to investigate the effects of low-level laser therapy (LLLT) with a diode gallium-aluminum-arsenide (Ga-Al-As) low-level laser device on the healing and attachment of titanium implants in bone.

Materials and Methods

Thirteen New Zealand white male rabbits weighing 3.0±0.5 kg were used for this study. Dental titanium implants (3.75 mm in diameter and 8.5 mm in length, US II RBM plus fixture; Osstem, Seoul, Korea) were implanted into both femurs of each rabbit. The rabbits were randomly divided into a LLLT group and a control group. The LLLT was initiated immediately after surgery and then repeated daily for 7 consecutive days in the LLLT group. Six weeks and 12 weeks after implantation, we evaluated and compared the osseointegration of the LLLT group and control group, using histomorphometric analysis, removal torque testing, and resonance frequency analysis (RFA). The results were statistically significant when the level of probability was 0.05 or less based on a non-parametric Mann-Whitney U-test.

Results

The implant survival rate was about 96%. Histologically and histomorphometrically, we observed that the titanium implants were more strongly attached in LLLT group than in control group. However, there was no significant difference between the LLLT group and control group in removal torque or RFA.

Conclusion

Histologically, LLLT might promote cell-level osseointegration of titanium implants, but there was no statistically significant effects.

Low Level Laser Therapy: A Panacea for oral maladies

AIM

To review the applications of low level laser therapy on various soft and hard oral tissues. A variety of therapeutic effects of Low Level Laser Therapy have been reported on a broad range of disorders. It has been found amenably practical in dental applications including soft as well as hard tissues of the oral cavity. LLLT has been found to be efficient in acceleration of wound healing, enhanced remodelling and bone repair, regeneration of neural cells following injury, pain attenuation, endorphin release stimulation and modulation of immune system. The aforementioned biological processes induced by Low level lasers have been effectively applied in treating various pathological conditions in the oral cavity. With is article, we attempt to review the possible application of Low Laser Therapy in the field of dentistry.

Effects of Light-Emitting Diode Photobiomodulation Therapy and BioOss as Single and Combined Treatment in an Experimental Model of Bone Defect Healing in Rats

The present study assesses histopathologically and histomorphometrically the effects of light-emitting diode (LED) photobiomodulation therapy (LPT) on bone healing in BioOss-filled femoral defects of rats. It has been reported that LPT modulates cellular metabolic processes, leading to an enhanced regenerative potential for biological tissues. Thirty-six male Wistar rats with femoral bone defects were divided into 4 groups: defect group (empty bone defect, without application of LPT), graft group (bone defect filled with BioOss, without application of LPT), (defect+LPT) group (empty bone defect, with application of LPT), and (graft+LPT) group (bone defect filled with BioOss, with application of LPT). An OsseoPulse LED device (wavelength: 618 nm; output power: 20 mW/cm2) was initiated 24 hours postsurgery and performed every 24 hours for 7, 14, and 21 days. The LPT-applied and BioOss-filled defects presented a higher amount of new bone formation with trabeculae formation. These defects showed statistically significant lower values of inflammation severity, and fewer remnants of biomaterial were present. Within the limitations of this study, LPT has positive effects on bone healing histopathologically and histomorphometrically for the defects filled with BioOss 3 weeks after the rats' femora injury.

New Bone Formation around Implants Inserted on Autologous and Xenografts Irradiated or not with IR Laser Light: A Histomorphometric Study in Rabbits

Use of biomaterials and light on bone grafts has been widely reported. This work assessed the influence of low-level laser therapy (LLLT) on bone volume (BV) and bone implant contact (BIC) interface around implants inserted in blocks of bovine or autologous bone grafts (autografts), irradiated or not, in rabbit femurs. Twenty-four adult rabbits were divided in 8 groups: AG: autograft; XG: xenograft; AG/L: autograft + laser; XG/L: xenograft + laser; AG/I: autograft + titanium (Ti) implant; XG/I: xenograft + Ti implant; AG/I/L: autograft + Ti implant + laser; and XG/I/L: xenograft + Ti implant + laser. The animals received the Ti implant after incorporation of the grafts. The laser parameters in the groups AG/L and XG/L were λ=780 nm, 70 mW, CW, 21.5 J/cm 2 , while in the groups AG/I/L and XG/I/L the following parameters were used: λ=780 nm, 70 mW, 0.5 cm 2 (spot), 4 J/cm 2 per point (4), 16 J/cm 2 per session, 48 h interval × 12 sessions, CW, contact mode. LLLT was repeated every other day during 2 weeks. To avoid systemic effect, only one limb of each rabbit was double grafted. All animals were sacrificed 9 weeks after implantation. Specimens were routinely stained and histomorphometry carried out. Comparison of non-irradiated and irradiated grafts (AG/L versus AG and XG/L versus XG) showed that irradiation increased significantly BV on both grafts (p=0.05, p=0.001). Comparison between irradiated and non-irradiated grafts (AG/I/L versus AG/I and XG/I/L versus XG/I) showed a significant (p=0.02) increase of the BIC in autografts. The same was seen when xenografts were used, without significant difference. The results of this investigation suggest that the use of LLLT is effective for enhancing new bone formation with consequent increase of bone-implant interface in both autologous grafts and xenografts.

Histological evaluation of bone healing using organic bovine bone in combination with platelet-rich plasma (an experimental study on rabbits)

OBJECTIVES

This study was carried out to histologically assess the effect of bone grafting materials extracted from bovine origin on the bone healing process either alone or when mixed with autologous platelet-rich plasma which could be used in many procedures of oral and maxillofacial bone and implant reconstructive surgery.

MATERIALS AND METHODS

Sixteen rabbits were used; three intrabony defects in the femur bone of each rabbit were created, one left unfilled for normal healing process and served as control, the second filled with xenogenic graft (Gen-Ox-lyophilized bovine bone organic matrix), and the third filled with (Gen-Ox-lyophilized bovine bone organic matrix) mixed with autologous platelet-rich plasma. Histological examination of the sections was performed after staining with H&E and Van Geison stains. The histomorphometric analysis including counting of bone cells (osteoblasts, osteocytes, and osteoclasts) with performance of osteon diameter and lamellar thickness at the end of the fourth week postoperatively was obtained.

RESULTS

It has been shown that with the use of autologous platelet-rich plasma in combination with the xenogenic bone graft prepared from bovine origin, new bone formation and neovascularization were enhanced significantly when compared with xenogenic graft alone.

CONCLUSION

The addition of PRP to xenogenic bone substitute in small bone defects of the rabbit femur showed a histomorphometric increase in bone formation (at the fourth week of healing).

CLINICAL RELEVANCE

Platelet concentrate might be used to accelerate the osseointegration of enosseous dental implants.

Application of laser-induced bone therapy by carbon dioxide laser irradiation in implant therapy

This study evaluated the application of laser-induced bone therapy (LIBT) to reduce implant healing time in rat tibia. Twenty 10-week-old female Sprague-Dawlay rats were used. The rats received laser irradiation (laser group) or sham operation (control group) on either side of the tibia. Five days after invasion, titanium implants were inserted in proximal tibia. Five, 10, and 20 days after implant placement, tibiae were collected. After taking micro-CT and performing a torque test, the tibiae were decalcified and 8-μm-thick sections were prepared. Specimens were stained with hematoxylin and eosin. Results. Micro-CT images, removal torque values, and histomorphometric analysis data demonstrated a significantly accelerated bone formation in the laser group earlier in the healing process. Conclusion. The use of laser irradiation was effective in promoting bone formation and acquiring osseointegration of titanium implants inserted in rat tibia. LIBT may be suitable for use in implant therapy.

Stability of dental implants after irradiation with an 830-nm low-level laser: a double-blind randomized clinical study

Little is known about the benefits of low-level laser therapy (LLLT) on improvement of stability of dental implants. The aim of this randomized clinical study was to assess the LLLT effect on implants stability by means of resonance frequency analysis (RFA). Thirty implants were distributed bilaterally in the posterior mandible of eight patients. At the experimental side, the implants were submitted to LLLT (830 nm, 86 mW, 92.1 J/cm(2), 0.25 J, 3 s/point, at 20 points), and on the control side, the irradiation was simulated (placebo). The first irradiation was performed in the immediate postoperative period, and it was repeated every 48 h in the first 14 days. The initial implant stability quotient (ISQ) of the implants was measured by means of RFA. New ISQ measurements were made after 10 days, 3, 6, 9, and 12 weeks. The initial ISQ values ranged from 65-84, with a mean of 76, undergoing a significant drop in stability from the 10th day to the 6th week in the irradiated group, and presenting a gradual increase from the 6th to the 12th week. The highest ISQ values were observed on the 10th day in the irradiated group, and the lowest in the 6th week in both groups. Under the conditions of this study, no evidence was found of any effect of LLLT on the stability of the implants when measured by RFA. Since high primary stability and good bone quality are of major relevancy for a rigid bone-implant interface, additional LLLT may have little impact macroscopically.

Mechanical evaluation of the influence of low-level laser therapy in secondary stability of implants in mice shinbones

The present work evaluates mechanically the bone-implant attachment submitted or not to low-level laser therapy, with wavelength of 795 nm, in a continuous way, with power of 120 mW. The implant was placed in one of the shinbones of 24 mice, randomly distributed into two groups. The experimental group was submitted to six laser applications, divided into four points previously established, two lateral and two longitudinal, six times 8 J/cm2 with an interval of 2 days, totaling the dose of 48 J/cm2. The control group did not receive laser therapy. The interval between applications was 48 h and the irradiations began immediately after the end of the implant surgeries. The two groups were killed on the 14th day and a bone block of the area was removed where the implant was inserted. A torque machine was used to measure the torque needed for loosening the implants. A statistically significant difference was observed between the two groups. The experimental group presented larger difficulty for breaking up the implant interface with the bone block than the control group. It can be concluded that with the animal model and the protocol of irradiation present in this study, the laser therapy demonstrated capacity to increase the attachment bone implant.

Influence of low-level laser treatment on bone regeneration and osseointegration of dental implants following sinus augmentation: An experimental study on sheep

OBJECTIVES

The aim of this experimental study was to evaluate if low-level laser treatment (LLLT) enhances bone regeneration and osseointegration of dental implants in a sinus graft model.

MATERIAL AND METHODS

Twelve sheep underwent a bilateral sinus floor elevation procedure with cancellous bone from the iliac crest. Implant insertion followed 4 weeks (six sheep) and 12 weeks (six sheep) later. Sixteen weeks after second-stage surgery, animals were sacrificed. Unilaterally, the grafted sinus and during the second-stage surgery the implant sites were irradiated intraoperatively and three times during the first postoperative week with a diode laser (75 mW, 680 nm). The overall energy density per irradiation was 3-4 J/cm(2). Biopsies of the augmented area were obtained during implant insertion and after scarification.

RESULTS

Bone regeneration within the grafted sinus histomorphometric analysis hardly differed between control and test side both 4 and 12 weeks after sinus grafting. Osseointegration measurements resulted in a significantly higher bone/implant contact (BIC) on the test side (P=0.045). Further evaluation of peri-implant bone tends to amount in significant higher percentage on the laser side (P=0.053).

CONCLUSION

The presented experimental study on sheep did not confirm a positive LLLT effect on bone regeneration within a cancellous sinus graft. Nevertheless, LLLT possibly has a positive effect on osseointegration of dental implants inserted after sinus augmentation.

The importance of coherence length in laser phototherapy of gingival inflammation—a pilot study

The aim of this study was to investigate if coherence length is of importance in laser phototherapy. Twenty patients with moderate periodontitis were selected. After oral hygiene instructions, scaling and root planing (SRP), one side of the upper jaw was randomly selected for HeNe (632.8 nm, 3 mW) or InGaAlP (650 nm, 3 mW) laser irradiation. One week after SRP, the following parameters were measured: pocket depth, gingival index, plaque index, gingival crevicular fluid volume, matrix metalloproteinase (MMP-8), interleukin (IL-8) and subgingival microflora. The irradiation (180 s per point, energy 0.54 J) was then performed once a week for 6 weeks. At the follow up examination, all clinical parameters had improved significantly in both groups. A more pronounced decrease of clinical inflammation was observed after HeNe treatment. MMP-8 levels were considerably reduced on the HeNe side, while there was no difference for IL-8 or microflora. Coherence length appears to be an important factor in laser phototherapy.

Evaluation of Low-Level Laser Therapy in the Treatment of Temporomandibular Disorders

OBJECTIVE

The purpose of this study was to assess the effectiveness of low-level laser therapy (LLLT) in the treatment of myogenic originated temporomandibular disorders (TMD).

BACKGROUND DATA

Limited studies have demonstrated that LLLT may have a therapeutic effect on the treatment of TMD.

METHODS

Thirty-nine patients with myogenic TMD-associated orofacial pain, limited mandibular movements, chewing difficulties, and tender points were included in this study. Twenty-four of them were treated with LLLT for 10 sessions per day excluding weekends as test group, and 15 patients with the same protocol received placebo laser treatment as a control group. These parameters were assessed just before, just after, and 1 month after the treatment.

RESULTS

Maximal mouth-opening improvement, and reductions in pain and chewing difficulty were statistically significant in the test group when compared with the control group. Statistically significant improvements were also detected between two groups regarding reduction in the number of tender points.

CONCLUSION

Based on the results of this placebo-controlled report, LLLT is an appropriate treatment for TMD and should be considered as an alternative to other methods.

Role of adult mesenchymal stem cells in bone tissue engineering applications: current status and future prospects

Mesenchymal stem cells (MSCs) have been demonstrated as an attractive cell source for tissue-engineering applications because of their ability to be easily isolated and expanded from adult bone marrow aspirates and their versatility for pluripotent differentiation into mesenchymal tissues. This review highlights advances and progress in bone reconstruction techniques for both the repair of site-specific bone defects and the attenuation of musculoskeletal disease symptoms associated with osteoporosis and osteogenesis imperfecta. Despite the enormous potential benefits of MSCs within these approaches, conventional tissue culture methods limit the clinical utility of these cells because of the gradual loss of both their proliferative and differentiation potential during ex vivo expansion. Novel strategies to overcome these limitations are discussed including cultivation in the presence of basic fibroblastic growth factor 2, induction of ectopotic telomerase expression, and ex vivo expansion on various collagenous biomaterials. In addition, this review also outlines mechanistic theories on the potential role of MSC-extracellular matrix interactions in mediating the retention of MSC proliferative and differentiation capacity after ex vivo expansion on collagenous biomaterials.

Photoengineering of Bone Repair Processes

OBJECTIVE

This paper aims to report the state of the art with respect to photoengineering of bone repair using laser therapy.

BACKGROUND DATA

Laser therapy has been reported as an important tool to positively stimulate bone both in vivo and in vitro. These results indicate that photophysical and photochemical properties of some wavelengths are primarily responsible for the tissue responses. The use of correct and appropriate parameters has been shown to be effective in the promotion of a positive biomodulative effect in healing bone.

METHODS

A series of papers reporting the effects of laser therapy on bone cells and tissue are presented, and new and promising protocols developed by our group are presented.

RESULTS

The results of our studies and others indicate that bone irradiated mostly with infrared (IR) wavelengths shows increased osteoblastic proliferation, collagen deposition, and bone neorformation when compared to nonirradiated bone. Further, the effect of laser therapy is more effective if the treatment is carried out at early stages when high cellular proliferation occurs. Vascular responses to laser therapy were also suggested as one of the possible mechanisms responsible for the positive clinical results observed following laser therapy. It still remains uncertain if bone stimulation by laser light is a general effect or if the isolate stimulation of osteoblasts is possible.

CONCLUSION

It is possible that the laser therapy effect on bone regeneration depends not only on the total dose of irradiation, but also on the irradiation time and the irradiation mode. The threshold parameter energy density and intensity are biologically independent of one another. This independence accounts for the success and the failure of laser therapy achieved at low-energy density levels.

Repair of Bone Defects Treated with Autogenous Bone Graft and Low-Power Laser

Because bone healing at the graft site is similar to a fracture repair, the purpose of the present study was to evaluate the effects of low-power laser irradiation on the repair of rat skull defects treated with autogenous bone graft. A defect measuring 3 mm in diameter was produced in the left parietal bone and filled with an autogenous bone graft obtained from the right parietal bone. The animals were divided into 3 groups of 20 rats each: nonirradiated control, irradiated with 5.1 J/cm, and irradiated with 10.2 J/cm. The laser (2.4 mW, 735 nm, 3.4 x 10 W/cm, 3-mm spot size) was applied three times per week for 4 weeks. Greater volume of newly formed bone was observed in the irradiated group with 10.2 J/cm. In both irradiated groups, a greater volume of newly formed bone occurred only in the first 2 weeks. The results demonstrated that laser irradiation at the grafted site stimulated osteogenesis during the initial stages of the healing process in a skull defect of the rat and that this effect was dose dependent.