Bone strain measurements and implant micro-surface analysis of drill-less self-threading dental implants - preliminary in-vitro results.

Innovative implant thread design enables timesaving one-stage insertion, with no need for prior osteotomy. This technique may impair bone and implant surface. The aim of this study was to investigate the strain levels produced in surrounding bone by this new treatment approach during and after implant placement and the effect of high insertion torque on the surface microstructure of the implants. Fresh bovine bone was collected and prepared to receive 2 types of drill-less self-threading dental implants differing in their thread design. Prior to implant insertion, two strain-gauges were cemented onto the bovine bone at each of the implant's neck recipient sites, one horizontally and one vertically. 5 Type 1 and 5 Type 2 implants were inserted into the bone with insertion torque of 80 Ncm. Strain was measured during implant insertion, and residual strain was recorded for 1 hour after implant placement. Implants micro-structure were analyzed by SEM. These results were compared to osteotomy and implant insertion strain data of conventional dental implants. A clear pattern of higher vertical compared to horizontal strain levels can be seen in the drill-less implants, compared to the opposite in drilling and insertion of conventional implants. Type 2 drill-less implant showed the lowest strain levels of all groups. Highest horizontal strain levels were measured for insertion of standard implants. Strain recovery was least prominent in the insertion stage of standard implants. Significant more cervical compression zones were detected in type 1 implant. However, SA and Rx. Surface roughness measurements didn't show any differences. Favorable horizontal stress distribution was noted in the 2 types of the novel drill-less implants, and comparable or lower vertical strains compared to regular protocol was also noted. Residual strain was low within all dimensions of bone. Conventional implant insertion protocol delivers strain to the frequently vulnerable bone around the implant neck. Horizontal residual strain, both in drilling and inserting conventional implants, was higher than the insertion strain of the drill-less implants. Implant surface roughness was not impaired by high insertion torque. High torque implant insertion may induce positive strain distribution within coronal part of the supporting bone. Implant surface were not impaired by high torque insertion methods.

Implant position for supporting maxillary over-denture: a clinical study.

The objective of this study was to compare the efficacy of supportive periodontal therapy (i.e. scaling and root planning, SRP) alone, versus a chemical device silica dioxide (SiO2) colloidal solutions (SDCS) used in association with SRP in the treatment of chronic periodontitis in adult patients.A total of 20 patients with a diagnosis of chronic periodontitis (40 localized chronic periodontitis sites) in the age group of 35 to 55 were selected. None of these patients have previously received any surgical or non-surgical periodontal therapy and demonstrated radiographic evidence of moderate bone loss. Two non-adjacent sites in separate quadrants were selected in each patient to monitor treatment efficacy (split mouth design). Clinical pocket depth (PD) and microbial analysis (MA) were analyzed at baseline day 15. SPSS program and paired simple statistic T-test were used to detect significant differences.Total bacteria loading, Tannerella forsitia and Treponema denticola loading were statistically reduced when SiO2 is locally delivered. SDCS gel is an adjuvant therapy which should be added to SRP in the management of moderate to severe chronic periodontitis.

Coverage of multiple recessions using the tunnel technique and a collagen matrix in the maxilla or mandible: a 6-month study.

Multiple recession defects in the dentition of the patients are routinely encountered in clinical practice and as such present a challenge for clinicians. Periodontal plastic surgical procedures aim to restore both esthetics as function in periodontal tissues. The objective of this study was to evaluate and compare the clinical efficacy of using a tunnel technique with a collagen matrix to cover multiple recessions in the maxilla or mandible. Fourteen patients were enrolled in the study. Patients in the maxilla-group and mandible-group were treated with xenogeneic collagen matrix using the tunnel technique. Clinical recordings were obtained at baseline and after 3 and 6 months. The percentage of average recession coverage (ARC), the percentage rate of patients with complete coverage of all recessions (CRC-1) and the percentage rate of complete coverage of recession defects (CRC-2) were evaluated after 3 and 6 months after the surgery. Statistically significant differences were observed in every parameter except probing depth between the baseline values compared to the values 3 and 6 months after the procedure in both groups. The mean ARC 6 months after the procedure was 96.8% in the maxilla and 81.3% in the mandible. At 6 months after the procedure, a complete root coverage was obtained in 2 out of 9 patients and 31 out of 39 recessions (79%) in the maxilla and 0 out of 5 patients and 10 out of 20 recessions (50%) in the mandible. A collagen matrix combined with the tunnel technique led to a satisfactory ARC, CRC- 2 and resulted in an unsatisfactory CRC-1.

The effect of gingival wall location on the marginal seal of class ii restorations prepared with a flowable bulk-fill resin-based composite.

SureFil SDR is a flowable resin-based composite that allows a single incremental bulk placement. The marginal seal of SureFil SDR at the gingival margins of class II restorations located apical to the cemento-enamel-junction (CEJ) has not been adequately evaluated compared to those located occlusal to the CEJ. Forty class II cavities were prepared in human molars. The gingival margins of 20 preparations were located 0.5 mm occlusal to the CEJ, and the other 20 preparations were located 0.5 mm apical to the CEJ. The cavities surfaces were bonded with XenoV dental adhesive and filled with SDR in one bulk increment up to 4 mm, after which they were covered with CeramX. The teeth were subjected to thermo-and load-cycling, and their gingival margins were exposed to 0.5% basic-fuchsin solution. The specimens were sectioned mesio-distally and scored for microleakage. A Wilcoxon test for pairwise comparison was performed to determine significance. Dye penetration was observed in 30% of the 20 restorations with cavo-surface margins located occlusal to the CEJ and in 55% of the 20 restorations with cavo-surface margins located apical to the CEJ. The bulk-fill flowable resin base SureFil SDR with XenoV dental adhesive provided a better marginal seal in class II restorations with gingival margins above the CEJ compared to restorations with gingival margins below the CEJ. SDR should not be recommended for class II cavity preparations with gingival margins located below the CEJ.

Survey results of currently used techniques and materials by dentists for fabrication of complete removable dental prostheses.

The present study was based on the screening of procedures and materials used by dentists in constructing complete removable dental prostheses, considering their professional background and years of experience. Questions arose regarding differences and similarities within the local dental society, of which approximately 75% were trained in Europeans countries with differences in academic background, and compared to international dentistry. A questionnaire web site was used in order to anonymously collect answers to the survey by general practicing and specialist dentists. The survey contained 28 multiple choice questions that were based on 5 parameters: years of experience, location of dental studies, specialization, location and field of specialization. One hundred one survey sheets were collected. The results show statistical significance (p less than 0.05) for the following comparisons: practicing time had an impact on practitioner-technician interaction, while the level of qualification had an effect on articulator and face-bow usage. Location of dental studies, specialization and residency had impact on final impression materials, teeth set-up as well as tooth shape and color selection. The differences found between dentists’ working techniques set the ground for future research that should focus on rating the success of the different methods towards a goal of creating recommendations for an ideal set of working techniques.

Bilateral symmetry of anterior maxillary incisors: evaluation of a community-based population.

The final outcome of dental treatment needs to be not only clinically sufficient, but also esthetically pleasing. Bilateral symmetry in the maxillary incisor teeth is of significant importance in esthetic dentistry. In restorative dentistry, symmetry refers to the appearance of balance around the dental midline. The purpose of this study was to measure and compare the maxillary incisor teeth dimensions from both sides of the dental midline, in order to asses if this symmetry occurs naturally. From the student community population at Tel Aviv University, 66 students between the ages of 20-35 (35 males, 31 females) were enrolled and gave consent. The inclusion criteria for this study were: upper maxillary incisors that have never undergone restorative or rehabilitative treatment, and no history of orthodontic treatment. Standardized digital photographs were taken, and the length and width of the maxillary central and lateral incisors were measured and proportions were calculated. SPSS was used to compare the measured differences between teeth on the left versus right of the midline. Tooth proportions were not significantly different between the left and right sides. Asymmetry was found only between the lengths of the maxillary lateral incisors (p=0.009); the width for these teeth was symmetrical. A significant statistical difference was not found on most parameters when evaluating symmetry of the upper incisors. Therefore, when treating the esthetically important anterior of the mouth, care must be taken to ensure bilateral symmetry to mirror the natural symmetry found in most patients.

The effect of enriching denture adhesives with chlorhexidine diacetate on the proliferation of Candida albicans: an in vitro analysis.

Denture adhesives are widely used in dentistry. The growth of Candida albicans on the denture base is common on both jaws, particularly in elderly patients. A strong correlation has been found between the growth of Candida albicans and dentures, potentially leading to denture stomatitis. Recent studies show that the addition of chlorhexidine diacetate (CHDA) to denture adhesives can have a protective effect against denture stomatitis. The aim of this research is to examine the antifungal properties of three denture adhesives when CHDA is added. We hypothesize that the addition of CHDA to denture adhesives will result in antifungal activity against Candida albicans. Three denture adhesive materials (Corega, Protefix and Kukident) were prepared with and without the addition of CHDA in order to measure whether CHDA increased the resistance of the adhesives to the growth of Candida albicans. Dynamic and static intercellular changes were assessed through direct contact test (DCT) and confocal microscopy. The tested materials were evaluated immediately after setting and at 14 days post-setting. When combined with CHDA, all three denture adhesive materials decreased Candida albicans growth compared to the control (p less than 0.0001). This inhibition of growth was more prominent in the first 24 h. The confocal microscopy results supported the DCT findings. The addition of CHDA to denture adhesive pastes inhibits growth of Candida albicans, and may potentially reduce the incidence of denture stomatitis. Further studies are warranted.

Temperature changes of one-piece implants during the setting of acrylic resin temporary crown. The effect of implant diameter. An in vitro study.

The purpose of this work is to evaluate changes in temperature of one-piece titanium implant surface during the setting of acrylic resin temporary crowns and to correlate thermal changes to implant diameter. Thirty-three one-piece implants (ARRP, Alpha-Biotec) were divided into 3 groups according to diameter size (G1=3 mm, G2=3.3 mm, G3=3.6 mm). Implants were mounted on an acrylic glass apparatus. Thermocouples were positioned at the most coronal thread. Lower incisor temporary polycarbonate crowns were filled with 80 µL of self-curing acrylic resin and positioned immediately on the implant abutment. Thermal changes of the implant surface were recorded continuously for 10 min. Data were statistically analyzed using one-way analysis of variance. The mean initial temperature (C0) of groups G1, G2 and G3 was similar (24.79±0.78ºC, 25.26±0.63ºC, 24.97±1.06ºC, respectively). The setting of the acrylic resin temporary crown resulted in a significant increase in the implant surface temperature of all groups. The mean thermal amplitude (ΔC) for groups G1, G2 and G3 were 6.79±1.02ºC, 6.61±0.94ºC, 6.65±1.26ºC, respectively. The mean time to maximum temperature (Tmax) for groups G1, G2 and G3 were 337.38±42.91 sec, 324.69±41.46 sec and 317.98±37.91 sec respectively (P>0.05). Direct application of auto-polymerizing resin to the titanium abutment of one-piece implants significantly increased the cervical implant surface temperature. Implant diameter did not influence the temperature changes.

The use of resorbable heterologous cortical lamina as a new sinus lift floor: a technical note.

Some graft materials such as a heterologous porcine cortical lamina have an excellent capacity in creating recipient sites that can be filled with cortico-spongious collagenated bone paste that reabsorbs, allowing for the reformation of good-quality bone. In this work a technique is proposed which makes use of resorbable cortical lamina in order to create a new sinus floor that can be filled with cortico-spongious bone paste. The adequate vascularisation of the graft combined with the integration of the lamina, which does not need to be removed, makes it possible to propose this technique as a potential alternative to those used so far.

Oxygen high level laser therapy is efficient in treatment of chronic periodontitis: a clinical and microbiological study using PCR analysis.

In periodontology, lasers have been suggested for the photodynamic therapy (PDT). Such therapy can be defined as the inactivation of cells, microorganisms or molecules induced by light and not by heat. The aim of our study is to assess the effect of Oxygen high-level laser therapy (OHLLT) in removing all bacterial deposits on root or implant surface by means of mechanical instrumentation and laser irradiation. OHLLT has two effects on targeted bacteria and tissues, decontamination and biostimulation. A total of 33 patients were randomly selected with a diagnosis of chronic periodontitis. The patients enrolled were 16 females and 17 males, six smokers and 4 diabetic patients. For each patient a periodontal charting was performed, assessing probing depth, plaque index and bleeding on probing at baseline and after 6 months. Microbiological analysis were performed with PCR Real Time, using paper tips to withdraw gingival fluid in periodontal pockets before and after treatment, at baseline and after 6 months. All patients were treated with OHLLT at baseline, after 1 week, after 2 weeks and every month for 6 months. After 6 months, all periodontal pockets were treated successfully, without complications and no significant differences in results. All clinical parameters showed an improvement, with a decrease both of plaque index (average decrease of 75%), bleeding on probing (average decrease of 62%) and probing depth (average decrease of 1.8 mm). After the treatment, a remarkable decrease in bacteria amount, both for each species and for total bacteria was observed except for Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis demonstrating that this laser protocol is effective on periodontitis treatment. OHLLT is efficient in treatment of chronic periodontitis as demonstrated by clinical and microbiological parameters, going beyond the traditional periodontal therapy.

The use of resorbable cortical lamina and micronized collagenated bone in the regeneration of atrophic crestal ridges: a surgical technique. Case series.

Some graft materials, such as micronized and collagenated bone, have an excellent capacity to be reabsorbed, allowing for the reformation of good-quality bone, but do not have the mechanical characteristics that would allow for stability in terms of shape and size. In this study, a technique is proposed which makes use of resorbable cortical lamina in order to create recipient sites that can be filled with micronized collagenated bone paste. The adequate vascularization of the graft combined with the integration of the lamina, which does not need to be removed, makes it possible to propose this technique as a potential alternative to those used to date.

[Impressions for implant supported prostheses].

A crucial aspect for successful outcome of implant supported restoration is it's accurate fit. The implant and the prosthetic component have precise machine fit, thus small discrepancies can lead to stress applied to the implants when connecting the restoration. The accuracy of the master cast is of great significance and depends on both clinical and laboratory factors. The purpose of this article is to discuss the various materials and methods available for impressions and the effect of implants' location, number and angulations on the accuracy of the impressions.

[Current status of implant-abutment--part 1: abutments for cemented versus screw retained restorations].

Fixed implant supported single crowns and fixed dental prostheses (FDPs) have become an accepted treatment option for replacing and restoring missing teeth. Recent systematic reviews summarized excellent 5- and 10-year survival rates for both reconstruction types. In screw-retained restorations, the fastening screw provides a solid joint between the restoration and the implant abutment or between the restoration and the implant itself. With cement-retained prostheses, this restorative screw is eliminated for many reasons: esthetics, occlusal stability, and fabrication of passively fitting restorations. The purpose of this article is to review the variety of implant-abutments available for fabrication of fixed implant-supported restoration and compare between the various abutment forms (screw vs. cement retained).

[The influence of dental implant surface on osseointegration: review].

Dental implant therapy is a prevalent and successful treatment, based on research and clinical experience. Ossointegration is the main factor that responsible for success or failure, initially of the implant, and in some cases followed with the whole treatment failure. The osseointegration process is influenced by several factors, among them the surface texture. Dental implants are available with different surface modifications that have been developed for enhancing clinical performances. This paper reviews the main treatments used for changing dental titanium implant surfaces, and compare the clinical performance of different types of implants. Based on existent literature, modified implant surface improves significantly the ability to achive optimise bone-implant contact and improve osseointegration. This review did not find any significant major differences between the surface modifications in use this days in terms of survival and success of specific implant. There are several methods that are no longer in use, due to poor clinical performance in the past.

An investigation of heat transfer to the implant-bone interface related to exothermic heat generation during setting of autopolymerizing acrylic resins applied directly to an implant abutment.

Excessive heat generation at the implant-bone interface may cause bone damage and compromise osseointegration. Autopolymerizing acrylic resins are commonly used intraorally to join impression copings and suprastructure components for soldering. The effect of heat generation at the implant surface related to the exothermic setting reaction of autopolymerizing acrylic resins applied to an attached abutment was examined in vitro. Two brands of autopolymerizing acrylic resin, Duralay and GC Pattern Resin, were compared. Acrylic resin was applied to a titanium alloy abutment connected to a titanium alloy cylindric implant in varying controlled volumes, with both bulk application and brush paint-on techniques. The implant was embedded in an acrylic resin mandible in a 37 degrees C water bath. Temperature changes were recorded via embedded thermocouples at the cervical and apical of the implant surface. Analysis of variance for repeated measures was used to compare treatment groups. A mean maximum increase in temperature of 4 to 5 degrees C was seen at the implant cervical for both materials, with a maximum temperature increase of 6 degrees C. No difference between Duralay and GC Pattern Resin was seen, except for bulk application to medium-sized copper bands at the implant cervical (P < .05). No difference between the bulk and brush techniques was seen for all options, except for GC, where bulk application to medium-sized copper bands produced higher temperatures than the brush technique (P < .05). Spray coolant reduced temperatures for bulk application of both Duralay and GC (P < .05).

Integrated electromyography of the masseter on incremental opening and closing with audio biofeedback: a study on mandibular posture.

PURPOSE: The purpose of this study was to test the hypothesis of a minimum electromyographic (EMG) rest position based on masseter surface EMG recordings of incremental opening and closing of the mandible with simultaneous audio EMG biofeedback. MATERIALS AND METHODS: Nineteen alert subjects in an upright seated position opened and closed the mandible in 1-mm increments 20 mm interincisally. An electronic recording device allowed each subject to maintain the vertical dimension of each increment while simultaneously reducing right masseteric muscle activity to the minimum possible level using audio EMG biofeedback. Integrated EMG masseteric activity was recorded at each static opening and closing increment. RESULTS: A mean plateau of integrated EMG output for all subjects with no minimum EMG point or circumscribed minimum EMG range for any of the nineteen subjects was shown. Analysis of variance for repeated measures showed no difference in opening and closing EMG levels (P = 0.27) and no interaction between opening, closing, and change in vertical dimension (P < 0.0001). CONCLUSION: These results, with those of other studies, raise questions regarding the validity of the concept of a unique physiologic rest position of the mandible with the masseter or associated muscles at minimum muscle activity. The idea of overlapping postural ranges appears to be more appropriate.

A 2-year follow-up of mandibular posture following an increase in occlusal vertical dimension beyond the clinical rest position with fixed restorations.

While resting mandibular posture is continuously changing, repeatable relations of 'physiologic rest position' (PRP) and 'clinical rest position' (CRP) are described in the literature. The PRP is defined as a position of minimal muscle activity and CRP as a more closed clinical reference relation. Relaxed resting posture (RRP) is a repeatable postural range obtained by operator-induced relaxation techniques. This article reports on measurements of mandibular posture in a patient group following an increase in occlusal vertical dimension (OVD) with fixed restorations beyond CRP over 2 years. The relationship of CRP and RRP in the restored and a non-restored control group is compared. The relationship of RRP and corresponding masseteric EMG values to baseline minimal EMG levels is reported for both groups. Resting face height adapted to the increased OVD and remained consistent over 1 and 2 years. The RRP was greater and significantly different from CRP in both groups (P = 0.0001). Results indicated that both CRP and RRP were postural ranges and not specific postural positions. The RRP occurred at minimum baseline EMG levels for both groups and appears to be consistent with physiologic rest position. The possibility of achieving minimal EMG levels at varying interocclusal rest space relations is discussed.

A preliminary study on the effect of occlusal vertical dimension increase on mandibular postural rest position.

The effect of increasing the occlusal vertical dimension on the mandibular postural relation was studied for eight subjects. Interocclusal rest space measurements were made weekly for 1 month prior and subsequent to increasing the occlusal vertical dimension by 3.5 to 4.5 mm interincisally using luted acrylic resin, complete-arch, fixed partial dentures. Interocclusal rest space measurements were made at the clinical rest position, which was established by requesting the subjects to close in maximum intercuspation and immediately relax their mandible. Interocclusal rest space measurements were also made at the more open resting position when the subjects were repeatedly instructed to relax and lapse into a semi-hypnotic condition termed "relaxed resting posture." Initial speech difficulties and muscle discomfort subsided after 1 to 2 weeks. Analysis of variance using repeated measures showed no significant difference in interocclusal rest space after increasing the occlusal vertical dimension for both clinical rest position and relaxed resting posture. A significant difference was found between clinical rest position and relaxed resting posture (P = .001), and no interaction was determined between clinical rest position, relaxed resting posture, and time.