Premolar Area Research Articles

Immediate implant placement in fresh alveolar sockets with a minimal split-thickness envelope flap: A randomised controlled clinical trial.

Comparing PES/WES scores, modified success rate, survival, success, buccal bone thickness and patient-reported outcomes of immediate dental implants placed in fresh alveolar sockets using a flap or a minimal split-thickness envelope flap (MSTEF). Implants following random assignment into a flap or MSTEF group were placed immediately in anterior and premolar areas. Guided bone regeneration and autogenous connective tissue graft were used in all cases. A temporary prosthesis was provided followed by the final prosthesis at 16-18weeks. Success and survival rates together with radiographic buccal bone thickness and patient satisfaction were evaluated at 12-month post-loading. The aesthetic outcome was evaluated through the Pink (PES) and White (WES) Aesthetic Score by 8 blind clinicians of different training background and incorporated in modified success criteria. 28 implants were placed on 28 patients. No statistically significant differences were noted in PES (10.54 control versus 10.80 test), WES scores (6.97 control versus 6.95 test) or success criteria including aesthetic parameters (modified success criteria) for the different specialty groups (Range 69%-92%). In addition, no statistically significant differences were noted in survival (100%), success (100%), buccal wall thickness between control (0.72±0.22) and test group (0.92±0.31) and patients' reported outcomes. Immediate dental implant treatment with flap/ MSTEF provided similar mean PES/WES scores, modified success rate, survival, mean buccal bone levels and patients' satisfaction. However, aesthetic failures were common in both groups.

Prosthetic complications and maintenance of implant retained maxillary and mandibular overdentures constructed with fully balanced and lingualized occlusal schemes : Randomized control clinical trial

Aim: The purpose of this study was to evaluate the prosthetic complications and maintenance of implant retained maxillary and mandibular overdentures constructed with fully balanced and lingualized balanced occlusal schemes. Materials and methods: Eight participants with edentulous maxillary and mandibular ridges received 4 implant fixtures in the lateral incisor and first premolar areas of maxilla and 2 implant fixtures in the cuspid areas of the mandible using the submerged surgical protocol. Maxillary and mandibular overdentures were constructed with either fully balanced occlusal scheme (group I) or lingualized balanced occlusal scheme (group II) and connected to the implants with Locator attachments after 6 months of implant insertion. Evaluation of prosthetic maintenance and complications for both maxillary and mandibular dentures in both groups were made after one year of denture insertion. Results: For maxillary and mandibular overdentures, group I had significant higher incidence of screw loosening, insert wear, insert replacement than Group II. While Group II had higher incidence of teeth wear than Group I. No significant difference in denture reline and insert distortion between both groups was noted. For mandibular overdentures, group I was associated with significant higher mucositis, soreness, ulcer decubitus than Group II. For maxillary overdentures, no significant difference in mucositis, soreness, hyperplasia or flabby ridges between groups was noted. Conclusion: Within the limitations of this study, Lingualized balanced occlusal concept is recommended for maxillary and mandibular implant overdentures as it was associated with significant lower prosthetic and soft tissue complications than fully balanced occlusal concept.

Experience in the use of high-molecular-weight hyaluronic acid in the treatment of chronic generalized periodontitis

As a rule, periodontal diseases are accompanied by marginal recession of the gums, loss of attachment and exposure of the roots of the teeth. Traditional drugs for injection treatment are being replaced by modern drugs based on high molecular weight hyaluronic acid, which are successfully and highly efficiently used for local therapy of inflammatory and destructive periodontal diseases. In order to restore the volume of soft tissues in the interdental spaces, eliminate recessions and bleeding of the gingival margin, a preparation of high molecular weight hyaluronic acid “Revident +” was used, which was injected into the base of the gingival papilla at a distance of 2—3 mm from its top with the bevel of the needle upwards. To assess gingival bleeding, the PBI (papilla bleeding index) index was used, which is a sensitive indicator of the severity of gingival inflammation. The magnitude of gingival recession before and after treatment was assessed according to its severity: mild — up to 3 mm, moderate — 3—5 mm, and severe — 6 and more mm. Examination of periodontal patients before and 1.5 months after the application of high molecular weight hyaluronic acid in the composition of the Revident + preparation showed that the degree of gingival bleeding according to PBI decreased significantly after the third visit from 4 to 2 and from 3 to 1, respectively. The degree of gingival recession in the area of the anterior group of teeth decreased by an average of 2.1 mm, in the area of premolars — by 2.5 mm, and in the area of molars — by 2.8 mm.

Stress Distribution in Cortical Bone around the Basal Implant - A Finite Element Analysis.

Aim:The aim of the study was to develop a model that represents a basal implant with stress distribution in the cortical bone on application of loads emulating masticatory forces.Materials and Methods:In this study, the stress distribution in the bone and the implant is evaluated by applying various loads that emulate the masticatory forces. The geometric models of cortical bone representing the premolar area and a basal implant model of the following specifications, longitudinal oval threaded pin (1.95 mm × 2.1/2.3 mm ø), height of the implant head (7.2 mm), and width of the implant head (3.5 mm) (BOI BS, IDHEDENTAL), were generated with Ansys software, and both the implant model and the bone model are superimposed to mimic the bone implant system as a unit.Results:Overall comparison of stress distribution on both implant shaft and implant neck showed that maximum stresses are located at implant neck irrespective of forces applied and minimum stresses are located at implant shaft. On overall comparison of stresses seen within the bone and the implant, it was observed that the maximum stresses were seen in the implant neck followed by the implant shaft followed by the bone interface.Conclusion:The present study concluded that the stress transmission is greatest during application of oblique load (70 N) followed by horizontal load (10 N) and the least by vertical load (35 N).

Factors Influencing the Accuracy of Freehand Implant Placement: A Prospective Clinical Study.

(1) Background: The objective of implant prosthetic restoration is to ensure the best possible rehabilitation of function and esthetics. Optimal positioning of the implant with regard to the bone availability, surrounding soft tissue, and prosthetic sustainability should be strived for during implant placement. The factors influencing freehand implant placement and the accuracy achieved with this procedure are investigated in this prospective clinical study. (2) Methods: Implants were placed in the single-tooth edentulous sites of the premolar and molar areas in 52 patients. Three-dimensional (3D)-planning was performed virtually prior to the freehand implant operation, and the desired position of the implant was provided to the surgeon. (3) Results: The deviations between the planned and the actually achieved position with freehand implant placement showed the following mean values and standard deviations: angle 8.7 ± 4.8°, 3D deviation at the implant shoulder 1.62 ± 0.87 mm, mesiodistal deviation 0.87 ± 0.75 mm, buccolingual deviation 0.70 ± 0.66 mm, and apiocoronal deviation 0.95 ± 0.61 mm. The type of jaw had a significant influence on accuracy. Major deviations were observed in the lower jaw. Furthermore, the timing of implant placement influenced the mesiodistal deviation and angular deviation; (4) Conclusions: Freehand implant placement demonstrated a higher level of deviation between the planned and actually achieved implant positions. In particular, the ranges showed a large spread. From a prosthetic point of view, there may be complications during the restoration of the prosthetic crown if the implant exit point is not optimally located or if the implants show a high angular deviation.

Mesenchymal stem cells and platelet-rich plasma-impregnated polycaprolactone-\u03b2 tricalcium phosphate bio-scaffold enhanced bone regeneration around dental implants

BackgroundFinding a material that supports bone regeneration is the concern for many investigators. We supposed that a composite scaffold of poly(ε) caprolactone and β-tricalcium phosphate (PCL-TCP) would entail desirable characteristics of biocompatibility, bioresorbability, rigidity, and osteoconductivity for a proper guided bone regeneration. Furthermore, the incorporation of mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) would boost the bone regeneration. We conducted this study to evaluate the bone regeneration capacity of PCL-TCP scaffold that is loaded with MSCs and PRP.Materials and methodsFive miniature pigs received 6 implants in 6 created-mandibular bony defects in the right and left lower premolar areas. The bony defects were managed according to the following three groups: the PCL-TCP scaffold loaded with MSCs and PRP (MSCs+PRP+PCL-TCP) group (n = 10), PCL-TCP scaffold loaded with PRP (PRP+PCL-TCP) group (n = 10), and PCL-TCP scaffold group (n = 10). After 12 weeks, the bone regeneration was assessed using fluorochrome bone labeling, μCT bone morphogenic analysis, and histomorphometric analysis.ResultsAll of the three groups supported the bone regeneration around the dental implants. However, the PCL-TCP scaffold loaded with MSCs and PRP (MSCs+PRP+PCL-TCP) group showed non-significant higher bone surface, bone specific surface, and bone surface density than the other two groups as revealed by the μCT bone morphogenic analysis. Histologically, the same group revealed higher bone-implant contact ratio (BIC) (p = 0.017) and new bone height formation (NBH, mm) (p = 0.0097) with statistically significant difference compared to the PCL-TCP scaffold group.ConclusionsPCL-TCP scaffold is compatible for bone regeneration in bone defects surrounding dental implants. Moreover, the incorporation of MSCs and PRP optimized the bone regeneration process with respect to the rate of scaffold replacement, the height of the regenerated bone, and implant stability.

Calcifying epithelial odontogenic tumour at an unusual site - A case report

Calcifying epithelial odontogenic tumour (CEOT), also known as Pindborg tumour, is a rare benign odontogenic tumour of locally aggressive behaviour forming 0.4–3.0% of all intraosseous tumours and 1% of all odontogenic tumours. CEOT is traditionally described as a rare, benign, locally-invasive, and slow-growing odontogenic neoplasm of exclusively epithelial tissue of origin. The most frequent location is the mandibular premolar and molar area, less frequently the lesion is found in the maxilla in the ratio 3:1, typically in the fourth to fifth decades of life with no gender predilection. It usually starts as a painless swelling and is often concurrent with an impacted tooth. The present case highlight the occurrence of CEOT in a younger individual on the unusual site i.e. in the left maxillary canine and premolar region as a painless swelling. This article also attempts to briefly emphasize the concepts of CEOT with the review of literature. Keywords: Calcifying epithelial odontogenic tumour, Pindborg tumour, Odontogenic tumour, Odontogenic neoplasm, Calcification.

Accuracy of implant impression techniques with a scannable healing abutment

Statement of problemScannable healing abutments are a convenient option to facilitate impression making for implant-supported restorations. However, studies evaluating the accuracy of the impression technique with scannable healing abutments are lacking. PurposeThe purpose of this in vitro study was to evaluate the accuracy of implant impression techniques with scannable healing abutments. Materials and methodsA partially edentulous mandibular dentiform model was fabricated with an epoxy resin, and implants were placed in the mandibular right second premolar and first molar areas. A maxillary dentiform model was then fabricated, and both models were mounted on an articulator. Scan data were obtained from the mounted models and set as the reference scans. The experimental models were divided into 4 groups (n=10). The conventional pick-up impression technique and definitive casts were used in group CI. The scan data from the definitive casts were obtained with a 3D model scanner. An intraoral scanner with a digital body scan was used in group DS. Group MS yielded definitive casts with dual-arch impressions with scannable healing abutments. The fabricated definitive casts were mounted and scanned with a 3D cast scanner. Intraoral scanning with scannable healing abutments was used in group IS. In all 4 groups, the interarch relationship in the maximum intercuspal position was obtained by scanning the facial aspect. The center of the implant head was set as a measurement point for linear intra-arch deviations and implant angle deviations. The mesiopalatal cusp tip of the maxillary right first molar was used to calibrate the linear interarch deviations. The data obtained from each group were compared with the data from the reference scan. As the data were not normally distributed, the Kruskal-Wallis test and Bonferroni correction were used for the analysis (α=.05). ResultsGroup MS exhibited significantly higher deviations in linear intra-arch and implant angles compared with the other groups (P<.05). No significant difference was found between the groups in linear interarch deviations (P>.05). ConclusionsThe accuracy of intraoral scanning with scannable healing abutments was comparable with that of conventional pick-up impression techniques and digital scans with scan bodies. However, model scanning with scannable healing abutments may not be clinically acceptable for implant impressions.

Evaluation of bone density using different orthodontic arch wires

Evaluation of bone density using different orthodontic arch wires Objective: The aim of the present study was to make an evaluation of the bone density in the mandible using three different orthodontic arch wire. Subjects and methods: Thirty orthodontic patients both males and females were selected and treated by the same researcher. The patients were randomly divided equally into three groups according to the type of wire that was used, so Group A,B and C will be used. Group A, this group included 10 patients treated with (CNA) wire. Group B, this group included 10 patients treated with (Cu NITI) wire. Group C, this group included 10 patients treated with (NITI) wire. Results: The results showed that bone density showed a decrease in premolar area of the mandible between the beginning of orthodontic treatment and the end of levelling and alignment stage. Conclusion: There was a decrease in tissue mineral density with using the three archwires with non-significant difference between them.

Evaluation of implant’s primary stability using Densah bur versus expander in patients with missing maxillary premolar (A randomized clinical trial)

Aim: This study aimed to evaluate implant primary stability using Densah bur in comparison with expanders in maxillary premolar area. Material and methods: This study was conducted on twenty patients. The patients were divided into two equal groups. Each patient received one implant at the edentulous site of missing first or second maxillary premolar. One group received implants after using Densah bur, while the other group received implants after using screw expander. After implant placement, Smart peg was placed on implant and Ostell was used to record ISQ. Implant stability was measured intraoperative and at weeks 2, 4, 6, and 8 for both groups. The collected results were tabulated and statistically analyzed. Results: The study results showed there was no statistically significant difference between (Expander) and (Densah bur) groups in ISQ reading except at surgery and week two where the highest mean value was found in (Expander) group, while the least mean value was found in (Densah bur) group. Conclusion: Within the limitation of this study, Densah bur enabled successful implant insertion with acceptable primary stability in the resorbed maxillary premolar area. Moreover, the Densah bur can be used in a faster manner.

Stress distribution around different abutments on titanium and CFR-PEEK implant with different prosthetic crowns under parafunctional loading: A 3D FEA study

Aim & objectivesClinical trials had concluded a significant relationship between implant failure and bruxism. A three-dimensional (3D) finite element analysis (FEA) was done to evaluate the stress distribution in straight and angled abutments around titanium and carbon fiber-reinforced polyetheretherketone (CFR-PEEK) implant with 2 different prosthetic crowns under parafunctional loading. Materials and methodTwelve 3D models of bone block were created representing the maxillary right premolar area with osseointegrated implants. The models were divided in two group; CFR-PEEK implant (n ​= ​6) and group titanium implant (n ​= ​6).Each group was subdivided based on implants with three different abutments (straight, 15°, 25° angled abutments) and having two different prosthetic crowns: porcelain fused to metal (PFM) and polyetheretherketone (PEEK). A vertical load of 1000 ​N was applied to the central fossa and an oblique load of 500 ​N (30°) was applied to the buccal incline of the palatal cusp. The von Mises stresses and principal stresses were analyzed using ANSYS software. ResultsCFR-PEEK and titanium implants produced similar stress in bone under vertical and oblique loading. Straight abutment showed better results than 15° and 25° angled abutments in all the groups. PEEK crown produced lesser stress than PFM crown under vertical and oblique loading. ConclusionThe study concluded that straight abutment along with PEEK crown could be given in patients with bruxism to reduce the stress concentration in bone, thus preventing possible implant failure. Titanium and CFR-PEEK implants with straight abutments if given, then it should be provided with an occlusal splint.

Gingival Fibroma: An Emerging Distinct Gingival Lesion with Well-Defined Histopathology.

Gingival growths, barring a few are mostly reactive and seldom exhibit significant true neoplastic potential. The common etiology is local irritation from dental plaque/calculus, trauma as well as medication-related overgrowth. Such lesions are easily distinguishable and categorized into diagnoses such as pyogenic granuloma, peripheral ossifying fibroma, etc. We present a previously undescribed, but commonly encountered, reactive gingival growth with unique histologic features and suggest the diagnostic term "gingival fibroma." An IRB approved retrospective review of the University of Florida Oral Pathology Biopsy Service encompassing years 2010-2019, was performed to select cases. Demographics, clinical data, and microscopic diagnoses were recorded and analyzed. Four board-certified oral and maxillofacial pathologists agreed upon and established the diagnostic criteria. These are: a prominent fibromyxoid stroma, variable cellularity, a whorled or storiform pattern of arrangement of the cellular elements, lack of significant inflammation or vascularity, and complete absence of calcification, and/or odontogenic islands. A total of 60 cases met all criteria and were included in the study. Age range in years was 14-87 with the mean at 45.11years. A striking female predilection (90%) was noted. Approximately 62% of cases were reported on the maxillary gingiva, followed by 38.3% in the mandibular gingiva. Majority, 66.7% were in the anterior incisor region followed by 11.7% in the canine/first premolar areas. All lesions were submitted as excisional biopsy, and 4 cases recurred within 2-3years of excision. In all cases, lesional tissue appeared to extend to the surgical base of the specimen. We present 60 cases of a histologically unique entity occurring exclusively on the gingiva and introduce the diagnostic term "Gingival Fibroma" for these lesions. Further studies with adequate clinical follow-up may help understand the exact clinical behavior of these lesions.

Outcomes of Mandibular Overdentures Supported by Four Short Implants Combined with Photobiomodulation Therapy.

The aim of this study was to clinically and radiographically evaluate mandibular overdentures supported by four short implants combined with two different doses of photobiomodulation (PBM). A split-mouth design was applied; six completely edentulous male subjects received four short implants in the canine and second premolar area. Short implants were inserted via a digital fully guided approach with a stereolithographic surgical guide. All patients received five PBM sessions immediately after surgery and every 48 hours. Group A (n = 6) implants on the right side received a dose of 3.75 J/cm2, and group B (n = 6) implants on the left side received a dose of 7.5 J/cm2. Evaluation of peri-implant probing depth (PIPD), modified Gingival Index (MGI), and vertical bone loss was performed at the time of prosthetic loading and 6 and 12 months later. The implant stability quotient (ISQ) was also assessed 6 and 12 months after loading. There was no significant difference between both groups regarding PIPD values. However, a minor but significant increase from the baseline (P < .001) was observed in PIPD values in both groups after 12 months. The MGI scores at the different time intervals were very low for both groups. The mean vertical bone loss after 12 months was minimal for both groups but statistically significant from the baseline (P < .001). ISQ values for both groups after 12 months revealed a significant increase from the baseline, and group B values were significantly higher than those of group A. Within the limitations of this study, a mandibular overdenture supported by four short implants is a valid treatment modality for atrophic mandibles, and a PBM dose of 7.5 J/cm2 has a potential positive influence on implant healing and osseointegration.

Influence of Implant Distribution and Palatal Coverage on the Strain of Splinted Implant and Overdenture in Maxillary Implant Overdentures.

Implant overdentures with splinted attachments have been used in clinical practice, and the effect of splinting on implants has been reported frequently. However, the effect of implant configuration of more than four implants and covering the palate with an overdenture has not been sufficiently examined. The purpose of this study was to reveal the effects of implant configuration and palatal coverage on both implant and denture strain in maxillary implant overdentures using splinted implants. Six implants were placed in the anterior, premolar, and molar areas in a maxillary edentulous model. Four strain gauges were attached to the implant surface, and Dolder bar attachments were used to splint implants distributed in various configurations. Two types of maxillary experimental dentures (with/without palatal coverage) were fabricated, and two strain gauges were attached at the midline. A vertical load of 98 N was applied, and the strains on the dentures and implants were measured. The strain measurements were compared using one-way analysis of variance and t test (P = .05). When comparing the implant strains, the strain was significantly smaller on the anterior and premolar implants when six implants were used, but there was no significant difference among the different implant configurations in the strain on the molar implants. Strains on anterior implants of the palateless overdenture were significantly greater than those of the overdenture with palatal coverage. When four implants were used, the strain on the palatal side of dentures without palate was significantly greater than that on those with palatal coverage. When six implants were used, there was no significant difference in the strain on either side between two types of dentures. When implants were splinted to each other using a denture without palatal coverage, the strain of dentures when six or two anterior and two posterior implants were used was lower. The difference of denture strains between two types of dentures was not significant when six implants were used, but was significant for all other configurations. Also, the difference of implant strains between two dentures was significant in anterior implants regardless of implant configuration.

Resilient Stud Versus Bar Attachments for Immediately Loaded Implants Supporting Mandibular Overdentures: 1-year Randomized Controlled Clinical Trial.

This study aimed to examine clinical and patient-centered outcomes of resilient stud and stress-free bar attachments used for immediately loaded implants supporting mandibular overdentures. Thirty edentulous patients with sufficient bone mesial and distal to the mental foramen received new dentures. The patients were randomly assigned into two groups. After 3 months of adaptation, four implants were placed in the canine and second premolar areas of the mandible using computer-guided surgery and the flapless surgical approach. Overdentures were connected immediately to the implants using either resilient stud (Locator) or stress-free implant bar (SFI-Bar) attachments. Marginal resorption of bone, plaque and gingival indices, pocket depth, and implant stability were evaluated for both groups at baseline (prosthesis delivery) and 6 and 12 months thereafter. Implant survival and patient satisfaction were calculated after 12 months. For both groups, marginal bone loss (P < .043), plaque scores (P < .001), and probing depth (P < .002) increased significantly with time. SFI-Bar recorded lower marginal bone loss (P = .048) and higher plaque scores (P = .021) and probing depth (P = .001) than Locator after 12 months of denture insertion. The implant survival was 96.6% and 98.3% for Locator and SFI-Bar, respectively. No significant difference was found in the survival rate between groups (P = .56). Locator showed significantly higher general satisfaction, satisfaction with retention, comfort, and cleaning of overdentures compared with SFI-Bar (P < .001). Within the limits of this investigation, both resilient stud and stress-free bar attachments can be used successfully with mandibular four-implant overdentures subjected to an immediate loading protocol. However, studs may be preferred regarding peri-implant soft tissue health, patient satisfaction with retention, cleaning, and comfort, and stress-free bar attachments could be more effective in terms of marginal bone preservation.

Gingival zenith evaluation in an Andean population from Ecuador

Objectives: The aim of this study was to evaluate the characteristics of the gingival zenith of the maxillary incisors, canines and premolars in an Andean population from Ecuador. Materials and methods: A total of 51 subjects (30 men and 21 women; mean age = 21 years) with healthy gingival tissue were recruited. Digital study models were obtained from maxillary casts and the features of the gingival zeniths including its position, gingival lines and level in the lateral incisors were analyzed. Results: The gingival zenith was distally displaced in all the maxillary central and lateral incisors and in 70.59%; 62.74% and 91.17% of the canines, first and second premolars, respectively. For the maxillary anterior teeth, the greater mean of displacement was verified in central incisors (0.89mm ±0.27 SD), followed by the lateral incisors (0.58mm ±0.22 SD) and the canines (0.48mm ±0.21 SD). The displacement levels in the central incisors were significantly higher in females compared to male participants (p=0.037). In addition, the ascending gingival line was the most common in the anterior dentition (right: 52.9%; left: 51%), whereas the descending one was the most prevalent in the premolar area (right: 58.8%; left: 70.6%). Lastly, the gingival zeniths of lateral incisors were more frequently located coronal to the gingival line (86.27%), to a mean distance of 0.82mm (0.1 – 3.1mm; ±0.46 SD) and without significant differences among the genders (p=0.520). Conclusion: The data obtained from the present study could be taken into consideration during dental esthetic treatments, especially for Andean patients.

Correlation between alveolar bone level and mandibular trabecular Pattern In Periodontitis Patients Of Belgaum: A Radiological Survey

Introduction – Bone is a living, dynamic tissue, which undergoes remodelling throughout life, especially in adults. Deterioration of bone microarchitecture involves changes in the thickness and number of trabeculae, separation of trabeculae, and morphometric changes in the trabecula. Some studies suggest that changes in bone metabolism are reflected more so in the trabecular pattern rather than the bone mineral density. To further explore this, a short-study was carried out to investigate radiographically the relationship between the alveolar bone level and different trabecular bone patterns in periodontitis patients. Materials and Methods – A set of panoramic radiographs of 30 subjects was taken from radiology section, which included both males and females. Average alveolar bone level in a quadrant was calculated for each patient. Trabecular bone in the mandibular premolar area was categorised using Taguchi et alcriteria. The two variables were analysed using Spearman’s correlation coefficient and regression analysis models. Result – A significant positive correlation was found between alveolar bone loss and density of trabecular pattern. Conclusion–With increasing grade of trabeculation, a larger alveolar bone loss can be expected. This may prove to be useful in preventing tooth loss as well as in implant planning. KeyWords: alveolar bone, trabecular bone pattern, panoramic radiographs.

Ultrashort Implants, Alternative Prosthetic Rehabilitation in Mandibular Atrophies in Fragile Subjects: A Retrospective Study.

This study aimed to evaluate the effectiveness of using ultrashort implants in the rehabilitation of jaws of fragile patients. The aim of the study was to retrospectively evaluate the survival rate of full-arch prosthetic rehabilitation on ultrashort implants, length 4 mm, 4 mm in diameter in the premolar and canine area and 4.5 mm in diameter in the molar area, with the insertion torque of 60 Nw and immediate loading. Nineteen patients were evaluated for 3 years clinically and radiographically. The significant majority of the patients at the 3 year follow-up (T4) presented a stable and functional implant-supported prothesis, and the survival rate of the implants was 85%, with a loss of 16 implants on 114 implants. The combination of the innovative implant surfaces and the correct project of the prostheses, with the related implant connection, determined a different timing in the therapy, allowing to obtain an immediate loading, which is currently demanded by patients. This and recent reports on short and ultrashort implant usage in atrophic jaws offer a good solution in critical cases. In conclusion, within the limits of the study, the full-arch rehabilitation with immediate loading on ultrashort implants showed good results with few postoperative complications and related low biological cost.

Proton Therapy for Mandibula Plate Phantom.

Purpose: In this study, the required dose rates for optimal treatment of tumoral tissues when using proton therapy in the treatment of defective tumours seen in mandibles has been calculated. We aimed to protect the surrounding soft and hard tissues from unnecessary radiation as well as to prevent complications of radiation. Bragg curves of therapeutic energized protons for two different mandible (molar and premolar) plate phantoms were computed and compared with similar calculations in the literature. The results were found to be within acceptable deviation values. Methods: In this study, mandibular tooth plate phantoms were modelled for the molar and premolar areas and then a Monte Carlo simulation was used to calculate the Bragg curve, lateral straggle/range and recoil values of protons remaining in the therapeutic energy ranges. The mass and atomic densities of all the jawbone layers were selected and the effect of layer type and thickness on the Bragg curve, lateral straggle/range and the recoil were investigated. As protons move through different layers of density, lateral straggle and increases in the range were observed. A range of energies was used for the treatment of tumours at different depths in the mandible phantom. Results: Simulations revealed that as the cortical bone thickness increased, Bragg peak position decreased between 0.47–3.3%. An increase in the number of layers results in a decrease in the Bragg peak position. Finally, as the proton energy increased, the amplitude of the second peak and its effect on Bragg peak position decreased. Conclusion: These findings should guide the selection of appropriate energy levels in the treatment of tumour structures without damaging surrounding tissues.

A dense sample of fossil primates (Adapiformes, Notharctidae, Notharctinae) from the Early Eocene Willwood Formation, Wyoming: Documentation of gradual change in tooth area and shape through time.

The Willwood Formation of the southern Bighorn Basin, Wyoming is a fluvial rock sequence that spans approximately 3 million years of early Eocene time. It has yielded one the largest collections of fossil mammals in the world including thousands of dentitions of extinct lemur-like primates known as notharctines. In the southern Bighorn Basin, specimens of these primates have been collected on numerous paleontological expeditions and the stratigraphic levels yielding the dentitions have been carefully recorded. Notharctine dentitions represent a rare opportunity to study morphological variation in a single anatomical system through time among closely related individuals. Prior studies of Bighorn Basin notharctines through time produced measurements of hundreds of specimens but I report here results from measurement and comparison of the dentitions and dentaries of more than 3,000 specimens, all stratigraphically mapped. Variation in premolar and molar area and variation in dentary depth are apparent throughout the section. Specimens with relatively small teeth and dentaries are known from the older part of the section. In younger rocks, variation in tooth area among specimens increases. Variation in tooth area is continuous and overlaps extensively both within and between stratigraphic levels. Other dental variables examined by inspection change in a mosaic and continuous fashion through the section. These features include variation in the presence and number of paraconids on the lower fourth premolar (p4), the size and shape of the entoconid notch on the lower first and second molars, and the relative development of the pseudohypocone, mesostyle, and cingula on the upper molars. These broad patterns can be identified despite notharctine alpha taxonomy being in need of extensive revision and, importantly, simplification. Such revision is beyond the scope of this article but is essential if we are to develop a taxonomy that is both free of stratigraphic influence and useful for rapid, repeatable species assignment. Boundaries among the patterns of tokogenesis, anagenesis, and cladogenesis are blurred in this dense sample of extinct primates. While pattern of evolution, a population-level phenomenon, may be difficult to falsify in the fossil record, this notharctine sample suggests that in the rare instance such as this, when the fossil record is densely sampled, change through time is continuous and more consistent with gradual evolution.