Mandibular Implant-supported Prostheses Research Articles

Five years of radiographic evaluation for the peri-implant bone changes of all-on-four implant prostheses constructed from different framework materials using different digital construction techniques

BackgroundThere is insufficient evidence recommending a framework material and a CAD/CAM manufacturing technique for mandibular implant-supported prostheses. The study objective was to evaluate the clinical application of different materials and construction techniques used for mandibular All-on-4 prosthesis on circumferential peri-implant bony changes after 5 years.MethodsThirty-six male patients with all-on-4 mandibular implant-supported prostheses were recalled and divided into three groups. Group PK (patients with frameworks milled from PEEK blocks), Group PSM (patients with frameworks milled from soft metal blocks), and Group SLM (patients with frameworks constructed with additive manufacturing; selective laser melting). The circumferential bone level on all implant faces was assessed with a CBCT. Two-way repeated measures ANOVA was used to compare vertical bone loss (VBL) and horizontal bone loss (HBL) between different groups, implant positions, and observation times followed by Tukey’s multiple comparisons.ResultsFor all observation times, there was a significant difference in VBL between groups for both anterior and posterior implants (P < .001). For anterior implants, group PSM showed the lowest VBL while group PK showed the highest for anterior and posterior implants. For all groups, HBL significantly increased after 5 years for both anterior and posterior implants (P < .001). For anterior implants, group PSM showed the highest HBL. For posterior implants, group PK and SLM showed the highest.ConclusionWithin the study’s limitations, mandibular implant-supported fixed frameworks fabricated with either milling from PEEK or soft metal blocks, or additive manufacturing (laser melting technology) exhibited significant vertical and horizontal bone height changes after 5 years.Clinical Trial Registry Number(NCT06071689) (11/10/2023).

Prosthetic framework improvement using lattice structure: A comparative finite element study of a mandibular implant-supported prosthesis

Objectives:An alternative option was proposed regarding the prosthetic rehabilitation of a fully edentulous mandible using only four implants. The aim was to reduce the stiffness of the prosthetic framework. To that end, the alternative option consists of a prosthetic framework optimized with a porous structure. Mechanical differences were analyzed between non-prosthetic mandible and restored mandible either with a conventional bulk titanium framework or with this alternative option. The non-prosthetic mandible corresponds to the mandible in its natural state, without prosthesis. This will be considered as the reference for comparison with restored models (mandible with prosthesis). Methods:Three models are used: the first one is the non-prosthetic mandible, the second one is the restored mandible with conventional bulk titanium prosthetic framework, and the third one is the alternative option. Prosthetic framework was optimized with the use of a lattice structure. A numerical analysis was performed (with Abaqus Standard software®) to obtain the effective parameters corresponding to equivalent homogeneous behavior. In the 3 models, physiological boundary conditions were used, considering the activity of several muscles of the masticatory system during three main tasks of mastication (incisive clenching, maximum intercuspation and unilateral molar clenching). Results:Numerical simulations allowed to obtain mandibular global kinematics, local displacement at the bone–implant interface and the state of strain at the bone–implant interface, for each masticatory tasks. For this comparative study, the non-prosthetic mandible model was used as a reference to observe the benefits of using a lattice prosthetic framework compared to a conventional bulk titanium framework. Conclusion:Compared to conventional titanium framework, the lattice prosthetic one appeared to be more respectful of the natural mandible kinematics, given by the reference model. It also resulted in strain values within the physiological loading range.

3D finite element analysis of the dental implant loss effect on the stress distribution in the mandibular implant-supported prosthesis

An implant-supported prosthesis may have as few as three supporting implants, and the loss of one of them may lead to the loss of the entire structure. The framework of the Trefoil design is a standard bar made of high-strength titanium. Cyclic loading of metals and metal structures brings about the effect reducing the strength characteristics and known as fatigue. Fatigue limit is the value of stress below which the cyclic loading can-not destroy the structure. The aim of the work is to determine the treatment tactics for a patient having lost a distal implant and justify it according to the results of a three-dimensional finite element analysis of the effect of one dental implant loss on the biome-chanics of a mandibular implant-supported prosthesis with three supports. Bridge loading modeling was carried out with the Ansys 19.3 finite element analysis package and thus the stress-strain condition of the prosthesis and its components, im-plants and the frame itself, namely the bar, were determined. The stress values obtained allowed to draw the conclusion about the condition of metal structures under cyclic load-ing. The geometric model represents the mandible, including the compact and spongy bone layers, a bridge structure with two implants screwed into the spongy layer, and arti-ficial teeth attached to the implant structure. The model was created with the use of a real patient’s computerized cone-beam tomogram (CBCT) findings. The finite element model consists of 383507 second-order tetrahedral elements and 619339 nodes. The compo-nents are interconnected by contact elements of the "bonded" type, imitating a rigid con-nection without slipping. With 220 MPa being the fatigue limit for the loaded titanium implant construction, it was concluded that extended prosthesis construction can withstand an unlimited number of loading cycles at 100 N loading with the maximum stress of 154 MPa occurring in the left part of the jaw. The clinician’s tactics was determined for the potential loss of function or removal of one of the three Trefoil supporting implants: the prosthesis must not be removed until reimplantation.

Biomechanics of internal connection in mandibular implant-supported prosthesis under effect of loadings and number of implants: A 3D finite element analysis

IntroductionThe success of bone-implant prostheses depends on several factors, among them an adequate distribution and passive adaptation of occlusal loading. Objectivethis study evaluated the stress distribution in mandibular implant-supported prosthesis with internal connection morse taper interface, under effect of number of implants (4 or 5) and loadings (bilateral 100 N, bilateral 300 N). Materials and methodsthe virtual models were subjected to analysis by 3D finite element method, across four experimental conditions. ResultsThe stress values were evenly distributed to the peri-implant bone and implants in all simulated conditions. Stress values did not increase in the same proportion as the increase in the applied load (from 100 to 300 N). The stress value was 1.1 times higher on the implants and nearly doubled (1.5–2 times) on the peri-implant bone. ConclusionFor mandibular implant-supported prosthesis, the morse taper interface is strongly recommended, with similar mechanical demand for four and five implants in both loading conditions. Five implants offered no additional benefit over four implants. The commercial pure titanium frameworks presented stress values close to the yield strength of the metal, especially at the intersection with the cantilever.

A completely digital approach to replicating functional and esthetic parameters in mandibular implant-supported complete-arch prostheses

Making an intraoral digital scan for fixed mandibular implant-supported complete-arch prostheses is a clinical challenge. The absence of references in the mandibular arch for precise scan alignment may complicate the correct digital design of the prosthesis framework. This article presents a straightforward method that allows a completely digital approach to digital scanning for fixed mandibular implant-supported prostheses.

Prosthetic design related to peri-implant bone resorption in microvascular free fibular flap among patients with oral cancer: A retrospective clinical study

Statement of problemProsthetic rehabilitation is challenging after tumor excision in patients with oral cancer. Prosthetic parameters may be compromised because of the physical limitations of the oral cavity. Although microvascular free fibular flaps are a common treatment modality for mandibular reconstruction and allow the placement of dental implants, fibular resorption under long-term functional loading is still a controversial issue. Research focusing on how prosthetic design affects fibular resorption around dental implants in an oral cancer population is lacking. PurposeThe purpose of this retrospective clinical study was to correlate the success of implant-supported prostheses in microvascular free fibular flaps with occlusal force and fibular resorption around the implants 7 years after functional loading. Material and methodsThe T-Scan III was used to measure occlusal force in 13 participants with oral cancer. Forty-seven successful endosseous dental implants (Biomet 3i) under functional loading in the participants from 2010 to 2017 were analyzed retrospectively. Prosthetic design including fibular length, rehabilitated arch length, and crown-to-implant ratios was estimated from panoramic radiographs. The intergonial distance was used to calibrate the panoramic radiographs to enhance accuracy. To compensate for panoramic distortion, all parameters were represented as a ratio such as fibular length/mandibular width; implant-supported prosthesis length/mandibular dental arch length; implant-supported prosthesis length/maxillary dental arch length; and mandibular dental arch length/maxillary dental arch length. A generalized estimating equation was used for longitudinal analysis to estimate the impact of variables on fibular resorption around the implants. ResultsIncreased length of the implant-supported prostheses compared with maxillary and mandibular dental arch length significantly impaired the maximal occlusal force (P=.045 and P=.029). The crown-to-implant ratios in the fibular flaps were not correlated with fibular resorption around the implants under long-term functional occlusion (P>.05). The increased ratio of the implant-rehabilitated mandibular to maxillary dental arch length showed a statistically significant tendency to reduce fibular resorption around the implants (P=.007). ConclusionsCrown-to-implant ratios were not significantly correlated with maximal occlusal force or fibular resorption around dental implants. Increasing the length of the reconstructed mandibular implant-supported prosthesis in the fibular flap will reduce occlusal force. The rehabilitated mandibular dental length should be as long as the maxillary arch for optimum occlusal stress distribution to maintain the peri-implant fibula bone level.

Electromyographic Evaluation of Jaw Muscles in Edentulous Patients with Implant-Supported Prosthesis

The purpose of this study was to evaluate the effect of implant-supported oral rehabilitation in the mandible on the electromyographic (EMG) activity during chewing in completely edentulous individuals. Material and methods: Twelve completely edentulous patients were selected for this study, being six females and six males, aged 55 to 65 years old. The patients were divided into three groups according to the treatment protocol; (GI) All the completely edentulous patients had conventional maxillary and mandibular complete denture, (GII) six patients had two mandibular implants supported overdenture at the canine region and (GIII) six patients had one mandibular implant supported over-denture at the symphesial area. All patients were submitted to EMG evaluation of the masseter, and the temporalis muscles, after three months of placement of the conventional prosthesis and after three months of both implant-supported systems by using different textures of foods. The recordings data were analyzed using One Way ANOVA followed by post hoc analysis using LSD test.P< 0.05 was considered statistically significant. Results: the highest EMG activity of the masseter and temporalis muscles was recorded by chewing soft and hard foods in GI, while the reduction of muscular activity after implant supported oral rehabilitation was seen. No significant differences in the analyzed EMG parameters were found between the patients in GII and GIII. Conclusion: mandibular implant-supported prosthesis in edentulous individuals revealed a decrease in EMG amplitude for the masseter and temporalis muscles during chewing, which may indicate adaptation to new conditions of stability provided by support of the complete denture in the mandibular arch

Stress Distribution in an Implant-Supported Mandibular Complete Denture Using Different Cantilever Lengths and Occlusal Coating Materials.

The aim of this study was to assess stress distribution in the bone-implant interface of a mandibular implant-supported prosthesis with different cantilever lengths, aesthetic coating materials, and implant abutments. A photoelastic model of an edentulous mandible, containing 5 external hexagon implants, was constructed. Experimental models were divided into 6 groups: group 1-UCLA component and metal bar; group 2-UCLA component and acrylic resin coating; group 3-UCLA component and porcelain coating; group 4-abutment and metal bar; group 5-abutment and acrylic resin coating; and group 6-abutment and porcelain coating. Forces were applied to the most anterior implant, the most posterior implant, and different cantilever lengths. The results showed a higher number of high-stress fringes as the cantilever length increased. Fringes were better distributed in groups with prostheses composed of acrylic resin and in groups that contained an abutment. The stress distribution in the bone-implant interface is improved when the cantilever is eliminated and when abutments in an acrylic resin prosthesis are used.

Maximum Bite Force of Edentulous Patients before and after Dental Implant Rehabilitation: Long-Term Follow-Up and Facial Type Influence.

(1) To evaluate patients' long-term maximum bite force (MBF) after rehabilitation with mandibular implant-supported prosthesis, (2) to assess the influence of facial pattern in MBF, and (3) to evaluate the relation between the dominant chewing side and MBF. Twenty-nine patients were selected. Pre- (T0) and immediate post-rehabilitation (T1) data of MBF were collected. In a follow-up visit 3 to 5 years after rehabilitation (T2), 24 patients participated. The patients were asked about dominant chewing side, and facial pattern was obtained by the initial lateral radiographs. There was statistically significant increase in MBF in T1 - T0 = 5.4 ± 4.3 kgf, T2 - T1 = 5.5 ± 6.0 kgf. There was no statistically significant difference in MBF considering facial type, brachyfacial (T0 = 4.4, T1 = 10.7, T2 = 17.6 kgf), mesofacial (T0 = 4.1, T1 = 9.7, T2 = 16.5 kgf), and dolichofacial (T0 = 3.4, T1 = 7.9, T2 = 12.6 kgf). There was no statistically significant relation between MBF and the dominant chewing side. It can be concluded that mandibular rehabilitation with dental implants improves MBF independent of the facial pattern and dominant chewing side.

Teeth movement in denture and implant-supported prosthesis influenced by microwave flask systems

Background/AimsThis study evaluated the teeth movement in maxillary dentures and mandibular implantsupported prostheses processed by microwave flasks. MethodsA model mounted on articulator was used to manufacture Co-Cr frameworks. Pins were placed for measurements on the incisal edge of upper and lower central incisors (I), buccal cusp of first upper and lower premolars (PM), and mesiobuccal cusps of upper and lower second molars (M). Distances I-I (incisor to incisor), PM-PM (premolar to premolar), M-M (molar to molar), RI-RM (right incisor to right molar), and LI-LM (left incisor to left molar) were measured before and after processing using a microscope (0.0005mm). Vertical misfit between abutment and implant platform was evaluated for regions A (left distal implant), B (left median implant), C (medial implant), D (right median implant), and E (right distal implant) in predetermined labial and lingual sites. Prostheses were divided into groups G1 – conventional flask, and G2 – experimental HH flask. Acrylic resin was microwaved at 1400 W (30% for 3min, 0% for 3min, and 60% for 3min). Horizontal teeth displacement and vertical misfit between abutment and implant platform were considered before and after procedures. Data were submitted to three-way ANOVA and Tukey's test (α=0.05). ResultsExcept for M-M distance, the teeth showed displacements without statistical difference for prosthesis and flask factors. There was no significant difference for vertical misfit values for both flasks. ConclusionDiferente flasks did not cause significant changes in the teeth displacement, except for M-M. Vertical misfit values were not influenced by the flasks.

In silico comparison of the reproducibility of full-arch implant provisional restorations to final restoration between a 3D Scan/CAD/CAM technique and the conventional method

PurposeThe aim of this article was to investigate the accuracy in the reproducibility of full-arch implant provisional restorations to final restorations between a 3D Scan/CAD/CAM technique and the conventional method. MethodsWe fabricated two final restorations for rehabilitation of maxillary and mandibular complete edentulous area and performed a computer-based comparative analysis of the accuracy in the reproducibility of the provisional restoration to final restoration between a 3D scanning and CAD/CAM (Scan/CAD/CAM) technique and the conventional silicone-mold transfer technique. Final restorations fabricated either by the conventional or Scan/CAD/CAM method were successfully installed in the patient. The total concave/convex volume discrepancy observed with the Scan/CAD/CAM technique was 503.50mm3 and 338.15mm3 for maxillary and mandibular implant-supported prostheses (ISPs), respectively. On the other hand, total concave/convex volume discrepancy observed with the conventional method was markedly high (1106.84mm3 and 771.23mm3 for maxillary and mandibular ISPs, respectively). ConclusionsThe results of the present report suggest that Scan/CAD/CAM method enables a more precise and accurate transfer of provisional restorations to final restorations compared to the conventional method.

Loss of teeth opposing implant-supported prostheses in the posterior mandible: a retrospective survey in dental clinics.

The main aim of this study was to investigate the loss of maxillary teeth opposing mandibular implant-supported prostheses (ISPs) placed at dental clinics. Participating dentists were asked to provide information on implant procedures they had undertaken between January 1, 1990, and December 31, 2009. Data were requested for procedures in which implants were inserted into only one side of the mandible in posterior regions and no implants were inserted in other regions. Data on a total of 383 patients were analyzed. Participants in this study consisted of 170 men and 213 women ranging from 20 to 78 years of age (mean age, 51.0 years). Natural teeth were divided into three groups: opposing teeth (teeth opposing ISPs), control teeth (teeth of the same type as the opposing teeth but on the other side of the maxilla), and other teeth. The mean observation period was 72 months. One hundred six teeth were lost during the observation period. Fourteen opposing teeth were lost (1.72%, 14/816), 15 control teeth were lost (1.84%, 15/816), and 77 other teeth were lost (0.98%, 77/7,891). The percentage of opposing teeth lost was significantly higher than that of other teeth. However, there was no difference in the rates of loss of opposing and control teeth. ISPs in posterior mandibular regions are not a risk factor for the loss of opposing teeth.

Horizontal Denture: A Prosthodontic Alternative for Severe Maxillary Atrophy

Horizontal Denture: A Prosthodontic Alternative for Severe Maxillary Atrophy

Stress analysis of different configurations of 3 implants to support a fixed prosthesis in an edentulous jaw.

This study's aim was to evaluate the stress distribution in a mandibular implant-supported prosthesis and peri-implant bone considering implant quantity, diameter and position using linear 3-D finite element analysis. Models of an anterior jaw comprised 4 groups according to implant quantity, diameter, and position: control group C, 5 regular implants; R, 3 regular implants; W, 3 wide implants; and DTR, 3 regular implants with the distal ones tilted 30° distally. The cantilever was loaded with an axial load of 50 N. Data was evaluated using von Mises stress on implants and maximum principal stress and microstrain on the bone. The W group showed the lowest value of maximum principal stress in peri-implant bone of the loaded side (4.64 MPa) when compared to C (5.27 MPa), DTR (5.94 MPa), and R (11.12 MPa). Lower stress values in the loaded implants were observed in the experimental groups when compared to the C group. However, the unloaded implants presented opposite results. All the screws of the W group presented lower stress values when compared to the C group. However, the R and DTR groups presented an increase in stress values with the exception of the loaded screw. A reduction in the number of implants associated with wider implants reduced the stress in the bone and prosthetic components.

Selection patterns of dietary foods in edentulous participants rehabilitated with maxillary complete dentures opposed by mandibular implant-supported prostheses: A multicenter longitudinal assessment

Documentation of long-term changes in food intake is lacking for those treated with a maxillary complete denture opposed by a mandibular, screw-retained, implant-supported fixed prosthesis. The purpose of this study was to evaluate the selection patterns of dietary foods over 5 years for edentulous participants treated in a multicenter prospective clinical trial that compared cast alloy versus laser-welded titanium frameworks of an implant-supported prostheses opposed by maxillary complete dentures to rehabilitate edentulous participants. The study assessed data from a multicenter prospective clinical trial that followed edentulous participants from an initial baseline of wearing existing complete dentures to implant placement, restoration with a mandibular implant-supported prosthesis opposed by a maxillary complete denture, to follow-up assessment of these treatments over 5 years. The 32 participants in the cohort were treated at 5 of 9 participating centers. The data collected included 2 dietary forms, a standardized 4-day food diary form, and a dietary habits questionnaire. Each participant completed forms before entering into treatment (control) and at the 1- and 5-year follow-up assessment after being treated with a maxillary complete denture opposing a mandibular complete-arch fixed implant-supported prosthesis. Descriptive statistics were calculated for each measure at each assessment point. Regression analysis and the Sign test were used to calculate change in the participants' nutritional status (α=.05). Among the findings, it was noted that difficulty in masticating hard, raw, and fibrous foods decreased and intake of vegetable portions increased significantly from 2.5 to 3.3 servings. Participant comfort in eating in public places and their enjoyment of eating were significantly improved from 50% of participants being uncomfortable with their prior complete denture treatment to only 4% after 5 years. Within the limitations of this study, it was concluded that vegetable intake and ability to masticate raw, hard, and fibrous food for these participants improved when they received a mandibular implant-supported prosthesis opposed by a maxillary complete denture. According to the analysis and findings, the overall eating experience was more pleasurable, and eating in public was more comfortable after replacement of complete dentures with a mandibular implant-supported prosthesis.

A fala nas diferentes modalidades de reabilitação oral protética em idosos

speech production in different modalities of oral prosthetic rehabilitation. to study the speech production of subjects submitted to different oral rehabilitation modalities. 36 elderly individuals (average = 68 years) of both gender were evaluated. Participants were divided in three groups: 13 subjects with natural teeth (A); 13 edentate using maxillary and mandibular conventional dentures (B); and 10 edentate using maxillary conventional dentures and mandibular implant-supported prosthesis (C). Prosthesis stability was evaluated by a dentist and speech samples were analyzed by five speech-language pathologists. In order to determine the frequency of speech sound alterations, the Percentage of Correct Consonants (PCC) was used. few individuals presented speech alterations. Group C presented a higher occurrence of speech alterations (23.08%). Locked articulation was present in all groups; the reduction in lip movement was observed for groups A and B; exaggerated articulation and absence of saliva control was observed for group C. A smaller Percentage of Correct Consonants value was observed for the linguodental phonemes, in groups B and C, followed by the alveolar phonemes. Group A presented the majority of individuals with no speech alterations. On the other hand, for groups B and C, lips and tongue projection was frequently observed. No statistical difference was found between the groups. Most of the individuals in group B presented unsatisfactory prosthesis stability, but no association was identified between speech alterations and prosthesis stability. despite the small sample, the results of the study suggest that individuals using dentures present alterations in linguodental and alveolar phonemes. The type of prosthesis and its stability do not seem to interfere in speech production.

Long-term treatment costs associated with implant-supported mandibular prostheses in edentulous patients

Purpose The study's aim was to report long-term costs in edentulous patients treated with mandibular implant-supported prostheses. Materials and Methods Ninety patients were divided into four groups based on the type of implant prosthesis (fixed or overdenture) and treatment year. Records were obtained from dental charts, and an economic analysis from the patient's perspective was conducted. Clinical time associated with various procedures was measured and applied to the four groups. Salary rates by age, occupation, and gender were used to value patients' time. Direct clinical and time costs over 10 years were converted to 2002 Canadian dollars using the Consumer Price Index and discounted at a 3% rate. A sensitivity analysis at an equal salary rate was carried out to test the robustness of the time costs. Results Initial treatment and maintenance costs over the observation period were significantly higher for fixed compared to overdenture prostheses. A significant improvement in maintenance costs for the first patient group treated with fixed prostheses was observed over the follow-up period. Longer term (15 years) treatment costs for the initial two groups were significantly higher for the fixed group. The sensitivity analysis at an equal salary rate demonstrated the same trend: Time costs were significantly higher for the fixed groups. Conclusion Long-term treatment costs indicated that the mandibular overdenture was a less expensive treatment compared to the fixed implant prosthesis.—Reprinted with permission of Quintessence Publishing. The study's aim was to report long-term costs in edentulous patients treated with mandibular implant-supported prostheses. Ninety patients were divided into four groups based on the type of implant prosthesis (fixed or overdenture) and treatment year. Records were obtained from dental charts, and an economic analysis from the patient's perspective was conducted. Clinical time associated with various procedures was measured and applied to the four groups. Salary rates by age, occupation, and gender were used to value patients' time. Direct clinical and time costs over 10 years were converted to 2002 Canadian dollars using the Consumer Price Index and discounted at a 3% rate. A sensitivity analysis at an equal salary rate was carried out to test the robustness of the time costs. Initial treatment and maintenance costs over the observation period were significantly higher for fixed compared to overdenture prostheses. A significant improvement in maintenance costs for the first patient group treated with fixed prostheses was observed over the follow-up period. Longer term (15 years) treatment costs for the initial two groups were significantly higher for the fixed group. The sensitivity analysis at an equal salary rate demonstrated the same trend: Time costs were significantly higher for the fixed groups. Long-term treatment costs indicated that the mandibular overdenture was a less expensive treatment compared to the fixed implant prosthesis.—Reprinted with permission of Quintessence Publishing.

Long-term treatment costs associated with implant-supported mandibular prostheses in edentulous patients

Purpose The study's aim was to report long-term costs in edentulous patients treated with mandibular implant-supported prostheses. Materials and Methods Ninety patients were divided into four groups based on the type of implant prosthesis (fixed or overdenture) and treatment year. Records were obtained from dental charts, and an economic analysis from the patient's perspective was conducted. Clinical time associated with various procedures was measured and applied to the four groups. Salary rates by age, occupation, and gender were used to value patients' time. Direct clinical and time costs over 10 years were converted to 2002 Canadian dollars using the Consumer Price Index and discounted at a 3% rate. A sensitivity analysis at an equal salary rate was carried out to test the robustness of the time costs. Results Initial treatment and maintenance costs over the observation period were significantly higher for fixed compared to overdenture prostheses. A significant improvement in maintenance costs for the first patient group treated with fixed prostheses was observed over the follow-up period. Longer term (15 years) treatment costs for the initial two groups were significantly higher for the fixed group. The sensitivity analysis at an equal salary rate demonstrated the same trend: Time costs were significantly higher for the fixed groups. Conclusion Long-term treatment costs indicated that the mandibular overdenture was a less expensive treatment compared to the fixed implant prosthesis.— Reprinted with permission of Quintessence Publishing.