A novel nonsurgical therapy for peri-implantitis using focused pulsed electromagnetic field: A pilot randomized double-blind controlled clinical trial

Pulsed electromagnetic field (PEMF) therapy modulates the immune response and is successfully used in orthopedics to treat osteoarthritis and improve bone regeneration. This may suggest that this treatment may consequently reduce peri-implant soft tissue inflammation and marginal bone loss. To compare clinical, radiographic, and immunological results following nonsurgical treatment for peri-implantitis with or without PEMF therapy. Patients with peri-implantitis were included: pocket probing depth (PPD) between 6 and 8 mm with bleeding on probing (BOP); crestal bone loss between 3 and 5 mm. A novel healing abutment that contained active (test) or inactive (control) PEMF was connected. PEMF was administered via the abutment at exposure ratio of 1/500-1/5000, intensity: 0.05-0.5 mT, frequency: 10-50 kHz for 30 days. Nonsurgical mechanical implant surface debridement was performed. Patients were examined at baseline, 1 and 3 months. Clinical assessment included: plaque index, BOP, PPD, recession, and bone crest level which was radiography measured. Samples of peri-implant crevicular fluid were taken to analyze interleukin-1β (IL-1β). Twenty-three patients (34 implants; 19 control, 15 test) were included. At the follow-up, mean crestal bone loss was lower in the test group at 1 and 3 months (2.48 mm vs. 3.73 mm, p < 0.05 and 2.39 vs. 3.37, p < 0.01). IL-1β levels were also lower in the test group at 2 weeks (72.86 pg/mL vs. 111.7, p < 0.05). Within all the limitation of this preliminary study, the test group improved clinical parameters after a short-term period compared to the control group.

Revealing leukocyte populations in human peri-implantitis and periodontitis using flow cytometry

OBJECTIVE

To identify, quantify, and characterize leukocyte populations in PI and periodontitis using flow cytometry.

METHODS

Fresh biopsies from human PI and periodontitis lesions were processed to a single-cell suspension. The immune cell types were identified using flow cytometry.

RESULTS

Twenty-one biopsies were obtained and analyzed corresponding to fourteen PI and seven periodontitis samples. Participants' average age was 63.95 ± 14.77 years without a significant difference between PI and periodontitis patients, the female/male ratio was 8/12, and mean PD was 8.5 ± 2.17. High similarity was found between periodontitis and PI in the main immune cell types. Out of the leukocytes, the PMN proportion was 40% in PI and 33% in periodontitis. T-cells 22% in PI and 18% in periodontitis. Similar proportions of B-cells 10% and macrophages 6% were found in PI and periodontitis. Dendritic and NK cells were found in low proportions (~ 1%) in PI and periodontitis. T-cell sub-analysis showed that CD4-positive were more prevalent than CD8-positive in both diseases (CD4/CD8 ratio of 1.2).

CONCLUSION

With the use of flow cytometry analysis, the leukocyte populations in human peri-implantitis and periodontitis were classified. In PI and periodontitis, we identified similar proportions of specific (CD4/CD8) and innate (dendritic and NK) immune cells. These results corroborate previous histological studies.

CLINICAL RELEVANCE

Flow cytometry analysis can be used to identify and quantify immune cells in PI and periodontitis, including sub-classification of T cells (CD4/8) as well as detection of cells that require multiple markers for identification (such as dendritic cells).

The influence of radio frequency-based toothbrush on the accumulation of calculus and periodontal health: A randomized double-blind controlled prospective study

OBJECTIVES

The use of a toothbrush with radio frequency (RF) has shown to be of benefit regarding the reduction of plaque, calculus, and dental staining and improving teeth shade compared to conventional powered and manual toothbrushes.

AIM

To evaluate the efficacy of the RF toothbrush in the reduction of calculus accumulation and its effect on periodontal parameters as well as subject satisfaction as compared to an identical sham-tooth brush.

MATERIALS AND METHODS

Patients who are under a strict maintenance program were included. Patients were allocated to test (RF toothbrush) or control (sham) randomly and were examined at baseline, one and three months. Clinical photos were taken and a consequential calculus assessment via ImageJ software. Clinical assessment included the following: plaque index (PI), bleeding on probing (BOP), probing pocket depth (PPD), and recession (REC). Patient satisfaction was assessed via a questionnaire.

RESULTS

Fifty-eight patients (29 control, 29 test) were included. At baseline mean PPD, BOP, PI, REC, and calculus accumulation were similar between the groups. Mean buccal calculus was lower in the test group at one month 4.0% versus 6.7%, p < .05. Calculus accumulation within the groups was lower in the test group at 1 and 3 months when compared to baseline at the buccal aspect (2.8% vs. 8.9%, p < .05% and 3.8% vs. 8.9%, p < .05) and lingual aspect (6.7% vs. 16.5%, p < .05% and 8.9% vs. 16.5%, p < .05). No statistically significant results were found regarding periodontal parameters PPD, BOP, PI, and REC. No difference was found between groups regarding patient satisfaction.

CONCLUSION

RF seems to have an additive effect on preventing calculus accumulation on the buccal aspect of anterior mandibular teeth at 1 month. Nevertheless, at 3 months, no difference between the toothbrushes is seen regarding calculus formation and maintaining periodontal health (ClinicalTrials.gov, Identifier NCT04640857).

Comparing operators and imaging techniques when performing trans-crestal sinus augmentation : A pilot study

AIMS

To compare baseline residual ridge height using CBCT and panoramic radiographs. A secondary aim was to examine the magnitude of vertical bone gain 6-months following trans-crestal sinus augmentation and compare it between operators.

METHODS

Thirty patients, who underwent trans-crestal sinus augmentation simultaneously with dental implant placement were included in this retrospective analysis. Surgeries were done by two experienced surgeons (EM and EG) using the same surgical protocol and materials. Pre-operative residual ridge height was measured on panoramic and CBCT images. The final bone height and the magnitude of the vertical augmentation were measured on panoramic x-ray taken 6 months following surgery.

RESULTS

Mean residual ridge height measured pre-operatively using CBCT was 6.07±1.38 mm, while these same measurements on the panoramic radiographs yielded similar results (6.08±1.43 mm), which were statistically insignificant (p=0.535).  Postoperative healing was uneventful in all cases. All 30 implants were successfully osseo-integrated at 6 months. The mean overall final bone height was 12.87±1.39 mm (12.61±1.21 and 13.39±1.63 mm, for operators EM & EG respectively (p=0.19).  Likewise, mean post-operative bone height gain was 6.78±1.57 mm. which was 6.68±1.32 mm and 6.99±2.06 mm for operators EM and EG respectively, p=0.66.   A moderate positive correlation was found between residual bone height and final bone height (r=0.43, P= 0.002). A moderate negative correlation was found between residual bone height and augmented bone height (r=-0.53, p= 0.002).    Conclusion: Sinus augmentation performed trans-crestally produce consistent results with minimal inter-operator differences between experienced clinicians.  Both CBCT and panoramic radiographs produced similar assessment of the pre-operative residual bone height.

Palatal soft tissue thickness around dental implants and natural teeth in health and disease: A cross sectional study

BACKGROUND

Previous studies focused on the influence of buccal mucosa thickness on peri-implant bone loss and inflammation, with inconclusive results. We observed substantially thicker palatal mucosal tissues at peri-implantitis sites. Therefore, we hypothesize that thick palatal peri-implant mucosa may be associated with deeper pockets and disease severity.

PURPOSE

To compare the thickness of the palatal tissue between natural teeth and implants in periodontal health and disease.

METHODS

Adult, non-smoker, healthy patients who visited our department for periodontal examination or treatment with restored implants in the posterior maxilla were recruited. Probing depth (PD), plaque index (PI), gingival index (GI) and radiographic measurements were recorded around implant and the contralateral tooth. Palatal tissue thickness was measured using a 30G needle that was inserted perpendicular into the mucosa at the bottom of the periodontal/peri-implant pocket and 3 mm coronally. Differences in the palatal tissue thickness between teeth and implants (in the same patient) was performed using t-test; as well as between peri-implantitis and non-peri-implantitis sites (among patients).

RESULTS

Sixty patients were included. Thirty-four implants were diagnosed with peri-implantitis and 26 healthy/mucositis implants with corresponding 24 healthy/gingivitis teeth and 36 teeth with attachment loss. Mean PD was higher around implants (4.47 ± 1.57 mm) than teeth (3.61 ± 1.23 mm, p = 0.001). The thickness of implants' palatal mucosa was higher than in teeth, at the base of the pocket and 3 mm coronally (4.58 ± 1.38 mm vs. 3.01 ± 1.11, p = 0.000; 3.58 ± 2.15 vs. 1.89 ± 1.11, p = 0.000, respectively). Mean palatal tissue thickness was 4.32 ± 2.35 mm for the peri-implantitis group while only 2.61 ± 1.39 in healthy implants, 3 mm coronal to the base of the pocket (p = 0.001). Palatal thickness at peri-implantitis sites was higher (4.32 ± 2.35) compared to periodontitis sites (2.23 ± 0.93), p = 0.000. Implant sites with palatal mucosa >4 mm (n = 32) had deeper mean pockets (5.58 ± 1.98) compared with thinner (≤4 mm) sites (n = 28) (4.48 ± 1.18, p = 0.018).

CONCLUSION

Thicker palatal tissue around implants is associated with deeper palatal pockets. Thick palatal tissue was found around implants diagnosed with peri-implantitis.

Digital photometric analysis of gingival response to periodontal treatment

OBJECTIVES

The color is a major factor in determining inflammation status in most gingival indices. Current indices have limitations mainly due to subjective nature. Digital color analysis can provide objective and accurate measurements. Thus, the present study aimed to assess by digital tool the gingival color in the different stages of an active periodontal treatment.

METHODS

Forty patients (19 males and 21 females) diagnosed with periodontitis (stage III/ IV, grade C) and treated surgically were included in the study. Clinical data (probing depth, bleeding on probing, clinical attachment level, gingival index, and gingival recession) and photographs by digital single-lens-reflex (DSLR) camera were recorded before initial periodontal treatment, which included scaling and root surface debridement (T0); the same parameters were then re-evaluated 6-8 weeks (T1) and 3 months after periodontal surgery (regenerative/resective) (T2). Differences between clinical parameters were calculated. The color space defined by the International Commission on Illumination (CIELab) was used to analyze gingival color.

RESULTS

In 56 periodontal surgical sites, 168 photographs were taken. The a*-value of the CIELab color system (higher a*- value translate to a stronger red color) was significantly reduced between T0 to T1 and further decreased at T2 (32.01, 29.28, and 27.45 respectively). Significant improvement in clinical parameters were found between T0 to T1 and T1 to T2. Sub-analysis of two distinct surgical interventions revealed that only regenerative procedure improved the a*-value, which was significantly correlated with pocket depth reduction.

CONCLUSIONS

Photometric analysis can be used to assess gingival color change during periodontal treatment of patients with periodontitis.

CLINICAL SIGNIFICANCE

Gingival inflammation is a major factor in periodontal assessment; nevertheless, all current gingival inflammation indices are partially subjective and only semi-quantitative. The digital photometric analysis may allow for accurate and objective gingival color assessment during periodontal treatment.

Histological and dimensional changes of the alveolar ridge following tooth extraction when using collagen matrix and collagen-embedded xenogenic bone substitute: A randomized clinical trial

Aim

To assess the horizontal and vertical dimensional changes of the alveolar ridge when using a collagen matrix in combination with collagen embedded xenogenic bone substitute, in comparison with natural healing after tooth extraction.

Methods

Patients that required extraction in non‐molars areas were included. Test group‐15 sockets were treated with deproteinized bovine bone mineral containing 10% collagen (DBBM‐C), covered by a procaine collagen membrane (CMXs). Control group‐15 sockets left for spontaneous healing. We used a custom‐made acrylic stent as a reference for alveolar ridge measurements. Six‐month postoperative, a single implant was placed in the experimental site. A core biopsy was taken from the site, using a trephine bur. Histomorphometric analysis assessed bone area, connective tissue, bone marrow, and residual bone graft.

Results

Six months later, horizontal ridge width at −3 mm showed a significant (p < 0.05) reduction in both groups albeit smaller in the test group 1.19 ± 1.55 mm, compared with the control 2.27 ± 1.52 (p = 0.087). At −5 mm sub‐crestally, statistically non‐significant reduction was noted in both groups, 1.61 ± 1.53 and 1.96 ± 1.52 mm for the test and control groups, respectively (p = 0.542). Vertical changes were smaller in the test group (0.14 ± 1.84 mm) compared with control (0.98 ± 1.49 mm). Keratinized tissue (KT) width was 7.3 ± 2.13 and 7.5 ± 3.49 mm in the test and control groups, respectively. Newly formed bone occupied 33.79 ± 17.37% and 51.14 ± 23.04% in the test and control groups, respectively, (p = 0.11). Connective tissue volume was 33.74 ± 13.81% and 30.12 ± 18.32% in the test and control groups, respectively (p = 0.65). Bone marrow occupied 19.57 ± 10.26% and 18.74 ± 17.15% in the test and control groups, respectively (p = 0.91). Residual graft occupied 12.9 ± 9.88% in the test group.

Conclusion

Alveolar ridge preservation using DBBM‐C resulted in reductions of the vertical and horizontal dimensions albeit not reaching statistical significance. The larger than anticipated standard deviation and smaller inter‐group differences might account for this phenomenon.

Severe Complications Following Maxillary Sinus Augmentation Using Poly L-lactide-co-ε-caprolactone-Coated Bovine Bone: A Retrospective Study

PURPOSE

To describe the postoperative complications following lateral wall sinus augmentation using (poly L-lactideco-ε-caprolactone; PLCL) and natural polysaccharides polymers-coated bovine bone (PBB). The secondary aims were to examine histologic findings and to propose complication management alternatives.

MATERIALS AND METHODS

This retrospective study included 61 subjects who underwent 67 lateral wall sinus augmentation procedures using PBB in the standard protocol. In cases that presented complications, treatment included additional antibiotic therapy, implant removal, or sinus reentry and total removal of the grafting material. In three cases, biopsy specimens were taken from the sinuses, and histologic analyses were performed.

RESULTS

The prevalence of postoperative complications was 32.8% (22 of 67 cases) in 18 of the patients (29.5%). The most prevalent symptoms were persistent pain (68.2%), swelling (63.6%), and oroantral fistula (54.5%). Radiographic signs appeared in 45.5% of the complications. A total of 24 implants failed; thus, an overall 80.3% survival rate was established at 19 months. The vast majority of complications (86.4%) were treated eventually with reentry surgery and revealed that the sinus was full with granulation tissue surrounding pieces of a nonossified rubber-like material. In cases where implants were placed, nonosseointegrated implants were surrounded by soft tissue. The sinus was cleaned thoroughly; the graft material remnants were removed together with inflamed parts of the sinus membrane, followed by chlorhexidine and saline lavages. In the biopsy specimens taken from the sinus cavity, there were no histologic features of new bone formation around the grafted material.

CONCLUSION

Lateral wall maxillary sinus augmentation using PBB was associated with an acute sinus infection histologic appearance and with a 7-times-higher failure rate compared with previous reports. This serious adverse event suggests that PBB cannot be recommended for maxillary sinus augmentations.

A single application of chlorhexidine gel reduces gingival inflammation and interleukin 1-β following one-stage implant placement: A randomized controlled study

BACKGROUND

Chlorhexidine (CHX) is a broad-spectrum antimicrobial agent commonly used in medicine. Application of (CHX) during abutment connection reduced the bacterial load at the implant-abutment interface. We hypothesize this treatment may consequently reduce peri-implant soft tissue inflammation and marginal bone loss.

PURPOSE

To evaluate the effect of a single application of CHX gel inside the dental implant internal hexagon on peri-implant tissue.

METHODS

Forty patients were recruited to this randomized, double-blinded, clinical trial. At the time of implant installation, a 4-mm healing abutment was connected to the implant. In the test group, chlorhexidine gel 1% was applied inside the implant hex, whereas control implants did not receive any gel. Clinical and radiographic measurements included soft tissue recession (REC), plaque index (PI), gingival index (GI), plaque index (PI), keratinized mucosa width (KM), probing depth (PD), and a peri-apical parallel x-ray. Peri-implant crevicular fluid (PICF) was collected for cytokine analysis. t-Test was used to compare changes from baseline to 3 months. Mann-Whitney U test and t test were used to compare test and control groups.

RESULTS

Twenty patients in the test group and 17 in the control group completed the study. One implant in the control group failed to osteointegrate. There were no significant differences between the control and test groups for REC changes, bone loss, and PD. GI was significantly lower in the test group after 1 week (1.79 ± 0.24 vs 0.75 ± 0.18, respectively) and 3 months (1.18 ± 0.21 vs 0.25 ± 0.12, respectively) although PI was equal. At 3 months, interleukin 1-β (IL1-β) was higher in the control group (p < 0.01) and a positive correlation was found between GI and IL1-β (r_s  = 0.60424, p = 0.00032).

CONCLUSIONS

Application of chlorhexidine gel reduced inflammation and IL1-β levels in the peri-implant soft tissue.

Thermal Changes at the One-Piece Implant Surface During the Setting of Two Autopolymerized Acrylic Resins

PURPOSE

To compare the temperature changes during the setting process of two provisional crown materials, polymethyl methacrylate (PMMA)-based acrylic resin (Ac) and bis-acryl composite resin (Co), at the first thread surface of one-piece implants.

MATERIALS AND METHODS

Twenty-two 3.3-mm-diameter one-piece implants were divided into two groups according to the provisional restoration material. Implants were mounted on a Plexiglas apparatus. A K-type thermocouple was fixed at the most coronal thread. Baseline (Bl Temp) and maximal (Max Temp) temperatures of both groups were recorded during the curing process. Total heat flux (THF) at the implant surface and thermal amplitude (Temp-Amp) were calculated. Differences between groups were compared using a t test for unpaired observations.

RESULTS

Upon curing, a statistically significant increase in the Max Temp from the Bl Temp was detected in both groups, with a greater increase in the Ac compared with the Co group. The Temp-Amp and the THF were two times greater in the Ac group than the Co group.

CONCLUSION

Significant heat is produced during the polymerization of PMMA-based resin and bis-acryl composite resin provisional crowns in one-piece implants. To decrease the risk of thermal challenge at the implant cervical aspect associated with restoration of immediately loaded implants, bis-acryl composite resin should be used.

Supportive periodontal therapy affects dental implants probing pocket depth, bleeding on probing, and bone level: a 4- to 8-year follow-up study

Objective: To evaluate implant and patient characteristics 4 to 8 years after implant installation in a study involving immediate fixed restoration of dental implants. Method and materials: The study was a follow-up of treated generalized chronic periodontitis patients who received immediate restorations on dental implants as part of a previous study. The patients were examined clinically and radiographically at implant placement, 6 months, 1 year, and 4 to 8 years later. Supportive periodontal therapy (SPT), teeth and implant probing pocket depth (TPPD and IPPD), bleeding on probing (BOP [teeth, TBOP; implant, IBOP]), and bone level (BL) measurements around implants were documented. Cases were divided into three groups according to annual SPT rate: 0.00 to 0.99/year (SPT0), 1.00 to 1.99/year (SPT1), 2.00 or more/year (SPT2). Results: Twelve patients, with 26 implants and 242 teeth, were included. The mean ± standard deviation follow-up period was 6.08 ± 1.25 years (range 4.04 to 7.94 years). All implants in the follow-up group were osseointegrated and survived during the follow-up period. The mean number of SPT appointments was 6.17 ± 5.65. A weak negative correlation was found between SPT rate and ΔTPPD (-0.24, P = .0005), whereas a strong negative correlation was found between SPT rate and ΔIPPD (-0.76, P = .0005). Negative correlations were found between SPT rate and ∆TBOP (-0.20, P = .003), and between SPT rate and ∆IBOP (-0.5, P = .009). A moderate correlation was found between SPT rate and ΔBL (0.46, P = .02). Conclusion: SPT has a significant positive effect on PPD, BOP, and on implant BLs in long-term follow-up and should be an essential part of implant therapy.

Clinical and Patient-Related Outcomes of a Tapered Implant System With Switched Platform Conical Abutments: A Private Practice Field Trial

The aim of this prospective cohort observational field trial was to examine 1-year survival and success rates of a recently introduced tapered implant system with switched platform conical abutments and to evaluate patient related outcomes of therapy. Partially edentulous patients aged between 18 and 75 years, with available bone height for dental implants ≥10 mm desiring to restore the missing tooth/teeth with implant supported restoration, were recruited by 7 periodontists in their respective private practices. Dental implants were installed according to standard implant therapy protocol. Three to 6 months postoperatively, after evaluating interim implant success, implants were restored by the referring dentists. Patient, Ramfjord teeth, and implant data, including baseline and 1-year postoperative, were collected. A total of 60 patients were recruited and received 117 implants. Complete 1-year clinical and radiographic data were available for 83 and 65 implants, respectively. Two implants failed during the first year, resulting in a 1-year survival rate of 98.3%. Mean implant probing pocket depth was 2.29 ± 0.84 mm. Mean radiographic bone distance from implant's shoulder at the mesial and distal sites at 1 year was 0.66 ± 0.5 and 0.79 ± 0.64mm, respectively, resulting in a success rate of 95.4%. Patient subjective evaluation of therapy exhibited a median pain experience of 1 and median esthetics, function, and general satisfaction evaluation of 10 on a scale of 1 to 10. The tapered conical connection dental implant system, used in private dental practices, shows good 1-year survival and success rates that are similar to other implant systems on the market.

Invasive cervical resorption following orthodontic treatment: Two cases involving the same patient

Invasive cervical resorption (ICR), a destructive form of external root resorption, is characterized by invasion of the fibrovascular tissue. This phenomenon is very rare and appears in 0.02% of the general population where the leading factors are orthodontics in addition to trauma, restorations, and bleaching. Heavy orthodontic force may increase the incidence to 1%. One of the main concerns regarding ICR is that it is often misdiagnosed with conventional diagnostic tools. In recent decades, a cone beam computed tomography (CBCT) imaging technique has become more common and can lead to a more accurate diagnosis and treatment plan. This case report describes a possible association between orthodontic treatment and ICR of a 14-year-old male, 18 months post orthodontic treatment. ICR in the mandibular right canine was diagnosed and verified by CBCT, and underwent combined endodontic-periodontal treatment. However, after orthodontic forced eruption was performed on this tooth to improve the bone defect, ICR was diagnosed on the mandibular right second premolar. The possible association between orthodontic treatment and ICR is discussed, as ICR was noted following orthodontic treatment on both occasions. This case report stresses the importance of ICR early detection by close attention to periodic radiographic checkups during orthodontic treatment. The use of modern diagnostic tools is highly recommended in suspicious cases.

CONCLUSION

A case is described in which the patient underwent two types of orthodontic treatment in the mandible at different time periods and developed ICR in two different teeth.

Primary stability following abutment preparation of one-piece dental implants

PURPOSE

One-piece dental implants are commonly used for the immediate restoration of missing teeth. In most cases, the clinician has to prepare the abutment intraorally to ensure a proper emergence profile and abutment angulation. However, this procedure might impair primary stability and thus potentially compromise osseointegration. The aim of this study was to determine the effect of abutment preparation on the primary stability of a one-piece implant system (UNO MIS).

MATERIALS AND METHODS

Implant stability was assessed by resonance frequency analysis with a novel custom-made external fixation device, validated previously, developed specifically for resonance frequency measurements of this implant. Thirty 3 × 13-mm implants were inserted in porcine jawbone with insertion torque of 15 Ncm (group A, 15 implants) or 30 Ncm (group B, 15 implants). Abutments were prepared by reducing the facial aspect of the implant abutment with a high-speed dental turbine (400,000 rpm) equipped with a medium-roughness diamond bur. Implant stability quotients (ISQs) were measured before and after abutment preparation.

RESULTS

Mean ISQs measured in group A and group B before abutment preparation were very similar (58.2 ± 1.4 and 57.4 ± 0.9, respectively; P > .05). Following abutment preparation, three implants in group A lost primary stability. The mean ISQ value in group A was reduced from 58.2 ± 1.4 to 54.9 ± 7.9 following abutment preparation (P < .05). The mean ISQ in group B was not affected by abutment preparation (57.4 ± 0.9 versus 57.3 ± 1.0; P > .05).

CONCLUSIONS

Abutment preparation of a one-piece dental implant inserted with low insertion torque might impair implant primary stability.

A novel device for resonance frequency assessment of one-piece implants

PURPOSE

Immediate loading and/or restoration of dental implants requires the assessment of implant stability, which is best performed by resonance frequency analysis (RFA) prior to loading. One-piece dental implants are usually used for immediate loading, but there is currently no available reliable method to assess the primary stability of one-piece dental implants. Therefore, this study sought to validate a novel device designed for RFA measurements of one-piece implants.

MATERIAL AND METHODS

Thirty (3.75 x 13 mm) internal-hex implants (Seven, MIS) were divided into two groups; 15 were placed in an acrylic glass block and 15 were placed in fresh porcine jawbone using 30 N/cm2 of insertion torque. Implant stability quotient (ISQ) values were measured using the Osstell Mentor device; then, a new external fixation device was attached to the implant abutment with a 10-mm arm extending from the implant to an internal-hex ring at its proximal end. ISQ values were measured at the implant's internal hex and at the internal hex of the device, and the damping ratio was calculated. The measurements were repeated with 15 (3 x 13 mm) one-piece implants (UNO, MIS) attached to the same device.

RESULTS

The damping ratio between the implant and the proximal device was 23.6% ± 4% in acrylic glass (50.1 ± 1.7 ISQ and 38.2 ± 1.8 ISQ, respectively) and 23.1% ± 3% in porcine bone (74.9 ± 2.8 ISQ and 57.5 ± 0.5 ISQ, respectively). ISQ values determined by the device on one-piece and two-piece implants were similar (57.4 ± 0.9 and 57.5 ± 0.5, respectively).

CONCLUSION

With the present validation of this external fixation device for the measurements of implant stability using RFA, it is now possible to measure primary stability of any one-piece implant system, obviating the need for custom-made Osstell adaptors.

[Root resection in the era of dental implants]

The treatment of furcation defects is one of the most challenging aspects of periodontal therapy. The periodontal therapist can utilize various treatment modalities, including: non surgical root debridement, local drug delivery, open flap surgery, tunneling, root resection, guided tissue regeneration and extraction. Each treatment method has its advantages and disadvantages. The dilemmas concerning tooth prognosis and prosthetic considerations in such cases are especially demanding, especially in comparison to implant therapy. The clinician's decision in these situations must comply with the objective condition in the particular case based on his abilities and knowledge and the patient expectations. In order to evaluate the relevancy of root resection procedures we reviewed the literature focusing on root resection therapy prognosis as well as the different therapeutic alternatives for furcated molar teeth. Root resection treatment guidelines, indications and contraindication are presented along with clinical examples. Root resection is currently a relevant treatment modality for furcation defects. By using proper case selection, good surgical technique, proper prosthetic treatment and good periodontal supportive care, a good 5 year prognosis can be achieved and complications can be minimized. In light of the growing literature concerning dental implants complications, extraction and dental implant placement should be recommended as the last option when all other conservative options cannot be used, or following their failure.

Heat production during prosthetic preparation of a one-piece dental implant

PURPOSE

Preparation of a one-piece dental implant abutment is often needed to achieve a proper emergence profile for a definitive restoration. However, this procedure may compromise osseointegration through the production of heat. The aim of this study was to measure heat production during implant abutment preparation with different volumes of water irrigation using a one-piece implant system.

MATERIALS AND METHODS

Forty-five one-piece dental implants were used in this study. The implants were divided into three groups according to the water flow rate used during abutment preparation: 30 mL/min (G30), 15 mL/min (G15), and without water irrigation (G0). Thermocouples were positioned at the most coronal and most apical threads. The abutments were prepared using a high-speed dental handpiece. Preparation continued for 120 seconds or until the implant temperature reached 47°C.

RESULTS

The time needed to reach 47°C in the most coronal thread of group G0 was 5.73 ± 1.16 seconds. After the preparation was stopped at 47°C, the temperature continued to increase until reaching a maximum temperature. None of the implants in the water irrigation groups reached 47°C. The time needed to reach maximum temperature was significantly shorter for group G0 than the groups with water irrigation. A strong positive correlation was found between coronal and apical recordings.

CONCLUSION

Prosthetic preparation of one-piece dental implants without irrigation induced a rapid increase in temperature. Water irrigation reduced heat production during abutment preparation in a dose-dependent manner.

Oral focal mucinosis associated with cervical external root resorption: a case report

BACKGROUND

Oral focal mucinosis (OFM) and cervical external root resorption are both rare lesions with an unknown etiology. In this article we report on a rare occurrence of OFM associated with cervical external root resorption.

METHODS

A 44-year-old female patient presented with sharp pain while drinking cold beverages and a firm localized gingival overgrowth adjacent to the buccal aspect of tooth #19. An excisional biopsy of the gingival lesion was taken and a deep cavity was found in the buccal aspect of the root. The cavity was restored with an amalgam filling.

RESULTS

The histological findings were of a well-circumscribed lesion composed of myxomatous connective tissue, which contained numerous stellate-shaped fibroblasts. Based on the findings, a diagnosis of OFM was made.

CONCLUSION

A rare case of OFM and cervical external root resorption occurring in the same site was described. A possible link between these 2 phenomena was hypothesized.

Cooling profile following prosthetic preparation of 1-piece dental implants

The aim of this study was to evaluate the effect of water irrigation on heat dissipation kinetics following abutment preparation of 1-piece dental implants. UNO 1-piece dental implants were mounted on Plexiglas apparatus clamping the implant at the collar. T-type thermocouple was attached to the first thread of the implant and recorded thermal changes at 100 millisecond intervals. Implants were prepared using highspeed dental turbine at 400,000 RPM with a coarse diamond bur. Once temperature reached 47 degrees C, abutment preparation was discontinued. Thirty implants were divided into 2 groups. Group A: Passive cooling without water irrigation. Group B: Cooling with turbine's water spray adjacent to the implant (30 mL/min). The following parameters were measured: T47 (time from peak temperature to 47 degrees C), T50%, T75% (time until the temperature amplitude decayed by 50% and 75%, respectively), dTemp50%/dt decay, and dTemp75%/dt decay (cooling rate measured at 50% and 75% of amplitude decay, respectively). Water spray irrigation significantly reduced T47 (1.37+/-0.29 seconds vs 19.97+/-3.06 seconds, P<0.0001), T50% (3.04+/-0.34 seconds vs 27.37+/-2.56 seconds, P<0.0001), and T75% (5.71+/-0.57 seconds vs 57.61+/-5.47 seconds, P<0.0001). Water spray irrigation also increased cooling capacity ninefold: dTemp50%/dt decay (4.14+/-0.61 degrees C/s vs 0.48+/-0.06 degrees C/s, P<0.0001), and dTemp50%/dt decay (1.70+/-0.29 degrees C/s vs 0.19+/-0.03 degrees C/s, P<0.0001). The continuous use of water spray adjacent to the abutment following the cessation of implant preparation might prove beneficial for rapid cooling of the implant.

IL-1 beta signaling is required for mechanical allodynia induced by nerve injury and for the ensuing reduction in spinal cord neuronal GRK2

Many neurotransmitters involved in pain perception transmit signals via G protein-coupled receptors (GPCRs). GPCR kinase 2 (GRK2) regulates agonist-induced desensitization and signaling of multiple GPCRs and interacts with downstream molecules with consequences for signaling. In general, low GRK2 levels are associated with increased responses to agonist stimulation of GPCRs. Recently, we reported that in mice with reduced GRK2 levels, inflammation-induced mechanical allodynia was increased. In addition, mice with impaired interleukin (IL)-1 beta signaling did not develop mechanical allodynia after L5 spinal nerve transection (SNT). We hypothesized that in the L5 SNT model mechanical allodynia would be associated with reduced neuronal GRK2 levels in the spinal cord dorsal horn and that IL-1 beta signaling would be required to induce both the decrease in GRK2 and mechanical allodynia. We show here that in wild type (WT) mice L5 SNT induces a bilateral decrease in neuronal GRK2 expression in the lumbar spinal cord dorsal horn, 1 and 2 weeks after L5 SNT. No changes in GRK2 were observed in the thoracic segments. Moreover, spinal cord GRK2 expression was not decreased in IL-1R(-/-) mice after L5 SNT. These data show that IL-1 beta signaling is not only required for the development of mechanical allodynia, but also to reduce neuronal GRK2 expression. These results suggest a functional relation between the L5 SNT-induced IL-1 beta-mediated decrease in GRK2 and development of mechanical allodynia.

Spontaneous pain following spinal nerve injury in mice

Autotomy behavior is frequently observed in rats and mice in which the nerves of the hindlimb are severed, denervating the paw. This is the neuroma model of neuropathic pain. A large body of evidence suggests that this behavior reflects the presence of spontaneous dysesthesia and pain. In contrast, autotomy typically does not develop in partial nerve injury pain models, leading to the belief that these animals develop hypersensibility to applied stimuli (allodynia and hyperalgesia), but not spontaneous pain. We have modified the widely used Chung (spinal nerve ligation [SNL]) model of neuropathic pain in a way that retains the fundamental neural lesion, but eliminates nociceptive sensory cover of the paw. These animals performed autotomy. Moreover, the heritable across strains predisposition to spontaneous pain behavior in this new proximal denervation model (SNN) was highly correlated with pain phenotype in the neuroma model suggesting that the pain mechanism in the two models is the same. Relative reproducibility of strain predispositions across laboratories was verified. These data indicate that the neural substrate for spontaneous pain is present in the Chung-SNL model, and perhaps in the other partial nerve injury models as well, but that spontaneous pain is not expressed as autotomy in these models because there is protective nociceptive sensory cover.

Genetic impairment of interleukin-1 signaling attenuates neuropathic pain, autotomy, and spontaneous ectopic neuronal activity, following nerve injury in mice

Peripheral nerve injury may lead to neuropathic pain, which is often associated with mechanical and thermal allodynia, ectopic discharge of from injured nerves and from the dorsal root ganglion neurons, and elevated levels of proinflammatory cytokines, particularly interleukin-1 (IL-1). In the present study, we tested the role of IL-1 in neuropathic pain models using two mouse strains impaired in IL-1 signaling: Deletion of the IL-1 receptor type I (IL-1rKO) and transgenic over-expression of the IL-1 receptor antagonist (IL-1raTG). Neuropathy was induced by cutting the L5 spinal nerve on one side, following which mechanical and thermal pain sensitivity was measured. Wild-type (WT) mice and the parent strains developed significant allodynia and hyperalgesia in the hind-paw ipsilateral to the injury compared with the contralateral hind-paw. The mutant strains, however, did not display decreased pain threshold in either hind-paw. Pain behavior was also assessed by cutting the sciatic and saphenous nerves and measuring autotomy scores. WT mice developed progressive autotomy, beginning at 7 days post-injury, whereas the mutant strains displayed delayed onset of autotomy and markedly reduced severity of the autotomy score. Electrophysiological assessment revealed that in WT mice a significant proportion of the dorsal root axons exhibited spontaneous ectopic activity at 1, 3, and 7 days following spinal nerve injury, whereas in IL-1rKO and IL-1raTG mice only a minimal number of axons exhibited such activity. Taken together, these results suggest that IL-1 signaling plays an important role in neuropathic pain and in the altered neuronal activity that underlies its development.

Pain behavior and nerve electrophysiology in the CCI model of neuropathic pain

Experimental painful peripheral neuropathy induced by chronic constriction injury (CCI) of the sciatic nerve results in cutaneous thermal and mechanical allodynia of the hind limb. Our histological studies indicate that the major pathology in the CCI model is a loss of large diameter myelinated fibers distal to the site of injury. Electrophysiological recordings from axons central to the lesion that respond to electrical stimulation distal to it, revealed severe fiber loss, reflected by a decrease (P < 0.05) from 5.2+/-6.8 to 0.5+/-0.1 axons/microfilament 5-9 days post operatively (dpo). At 12-15th dpo some recovery was seen, i.e. 1.5+/-0.28 axons/microfilament in the CCI group. The ratio of A- to C-axons in the control group remained constant throughout the experiment. A distinct area in the paw served by the injured nerve was selected to study the response of axons in each microfilament to mechanical stimulation with von Frey monofilaments. In the control group, 91%+/-0.6 of the microfilaments had at least one axon with a receptive field in this area. This decreased to 17%+/-2.9 in the CCI group 5-9 dpo, but had partially recovered to 44+/-4.2% by 12-15-dpo. Our conclusion is that in the CCI model there is an equal reduction in the number of A and C axons conducting past the lesion site, thus preserving a constant ratio between the two fiber populations. This is true despite the apparent preservation of C-fibers observed in previous histological studies.

Suppression of human hepatoma in mice through adoptive transfer of immunity to the hepatitis B surface antigen

BACKGROUND/AIMS

Adoptive transfer of immunity against hepatitis B surface antigen (HBsAg) has previously been shown to occur in mice and humans through transplantation of bone marrow cells from donors immunized against HBsAg (anti-HBs) to non-immune recipients. In the present study we evaluated the effect of adoptive transfer of immunity to HBsAg on the growth of HbsAg-secreting hepatocellular carcinoma (HCC) xenografts in athymic mice.

METHODS

Immunocompetent mice were immunized with recombinant HBsAg. Bone marrow cells from anti-HBs+ mice were injected intravenously to irradiated athymic Balb/c mice which had been previously transplanted subcutaneously with Hep3B human hepatoma cells. Treatment groups included mice receiving bone marrow transplantation from HBV-immunized (anti-HBs positive) and non-immunized (anti-HBs negative) donors.

RESULTS

At 9 weeks post bone marrow transplantation, tumor volume and serum alpha-fetoprotein levels in athymic mice receiving HBV-immune bone marrow cells were 11.5 mm3 and 363 ng/ml, respectively, as compared to 1579 mm3 and 19,000 ng/ml, in recipients of non-immune bone marrow transplantation (p<0.005). T-cell depletion of antiHBs+ immune bone marrow prior to transplantation decreased the anti-tumor effect but did not abolish it. A mild nonspecific, bone marrow-derived, graft versus tumor effect was observed in mice transplanted with human hepatoma cells that do not express HBsAg.

CONCLUSIONS

Adoptive transfer of immunity to HBV facilitates suppression of experimental human HCC expressing HBsAg. This effect is the result of a combination of specific anti-viral surface antigen effect and a nonspecific graft versus tumor effect.

Alterations in human fecal flora, including ingrowth of Clostridium difficile, related to cefoxitin therapy

To evaluate the effects of parenteral cefoxitin therapy on human fecal flora, we cultured fecal specimens obtained from six patients before, during, and after therapy and used standard methods to identify and quantify all microorganisms. The major changes (observed in at least three patients) included the acquisition or proliferation of group D Streptococcus species, coagulase-negative Staphylococcus species, cefoxitin-resistant members of the family Enterobacteriaceae, Pseudomonas species, and various species of the Bacteroides fragilis group. The most striking finding was ingrowth of Clostridium difficile, noted in five of the six patients. There was concomitant eradication or decrease of cefoxitin-susceptible Enterobacteriaceae family members, Bacteroides species other than the B. fragilis group, Clostridium species other than C. difficile, and Lactobacillus species. These marked alterations of fecal flora may have important clinical consequences.