Agenesis Of Premolars Research Articles

Association between molar incisor hypomineralisation and tooth agenesis: a cross-sectional study in Brazilian children and adolescents.

The aim of the present was to assess the association between MIH and tooth agenesis (TA) in orthodontic patients from the Federal University of Rio Grande do Norte, Natal, Brazil. A cross-sectional study was performed to evaluate the presence of MIH and TA in a sample of 371 pretreatment orthodontic records from patients aged 9-18years. Statistical analyses were performed using the Chi-square and Fisher's exact tests, and logistic regressions. There was a statistically significant association between the prevalence of tooth agenesis and MIH. A higher percentage of third molar agenesis, maxillary premolar agenesis, and mandibular second premolar agenesis was observed among children with MIH-affected teeth. Patients with MIH had a 2.43 times greater chance of third molar agenesis, and a 5.88 times higher likelihood of mandibular premolar agenesis. There is a weak association between MIH and TA. Furthermore, the presence of hypomineralised molars increases the risk of tooth agenesis.

Evaluating the efficiency of mandibular molar protraction using Herbst appliances versus temporary anchorage devices: a retrospective case-controlled study

BackgroundMandibular second premolar agenesis is a common problem in orthodontics and is often treated in conjunction with maxillary counterbalancing extractions. However, in cases without maxillary crowding or dental protrusion, space closure may pose challenges leading to compromised occlusal results or patient profile. Multiple techniques have been described to treat these patients; nevertheless, there is a paucity of data comparing effectiveness of space closure utilizing various anchorage techniques. The goal of this study is to assess the effectiveness of the Herbst device during mandibular molar protraction and compare it to the use of temporary anchorage device (TADs) in patients with mandibular second premolar agenesis.Materials and methodsThis retrospective study included 33 patients with mandibular premolar agenesis treated without maxillary extractions. Of these patients, 21 were treated with protraction Herbst devices and 12 with TADs. Changes in molar and incisor positions, skeletal base positions and occlusal plane angulations were assessed on pretreatment (T0) and post-treatment (T1) lateral cephalograms. Scans/photographs at T0 and T1 were used to evaluate canine relationship changes representing anchorage control. Space closure and breakage/failure rates were also compared. Data was analyzed with paired and unpaired t-tests at the significance level of 0.05.ResultsWithin the Herbst group, changes in mandibular central incisor uprighting and mandibular molar crown angulations were statistically significant. However, no significant differences were noted between the Herbst and TAD groups. Protraction rates as well as overall treatment times were comparable (0.77 mm/month vs. 0.55 mm/month and 3.02 years vs. 2.67 years, respectively). Canine relationships were maintained or improved toward a class I in 82.85% of the Herbst sample, compared to in 66.7% of the TAD sample. Emergency visits occurred in 80.1% of the Herbst group, with cementation failures or appliance breakages as the most common reasons.ConclusionThe Herbst device could be a viable modality in cases with missing mandibular premolars where maximum anterior anchorage is desired, or if patients/parents are resistant to TADs. Furthermore, they could be beneficial in skeletal class II patients with mandibular deficiency who also need molar protraction. However, the increased incidence of emergency visits must be considered when treatment is planned.

Association between molar-incisor hypomineralisation and dental anomalies.

Common etiological factors have been reported in the development of molar-incisor hypomineralisation (MIH) and dental anomalies (DA). To assess the association between MIH and DAs. A cross-sectional study was performed to evaluate the presence of MIH and other six DAs in a sample of 415 pretreatment records from patients aged 9-18 years. Statistical analyses were performed using the chi-squared and Fisher's exact tests, and logistic regressions. There was statistically significant association between the prevalence of DAs and MIH (CI: 1.43-2.43, φ-coefficient: 0.204, PR: 1.87). Higher percentage of tooth agenesis (CI: 1.37-1.68, φ-coefficient: 0.271, PR: 1.50), maxillary premolar agenesis (CI: 1.70-3.65, φ-coefficient: 0.125, PR: 2.49), mandibular second premolar agenesis (CI: 1.68-3.16, φ-coefficient: 0.172, PR: 2.30) and distoangulation of the mandibular second premolars (CI: 1.31-3.47, φ-coefficient: 0.103, PR: 2.13) was observed among children who had MIH-affected teeth. Individuals with MIH had a 2.95 times greater chance of having DAs (R2 = .153). The number of patients with DAs was higher when the first molar showed severe defects (OR = 4.47; R2 = .149). There is a weak association between MIH and DAs. Patients with severe MIH lesions have a slightly higher risk of presenting DAs.

Patterns of tooth agenesis in individuals with Down syndrome: A secondary analysis using the Tooth Agenesis Code.

Tooth agenesis (TA) is common in Down syndrome (DS). It is unknown whether this agenesis occurs in specific patterns, which is important regarding treatment planning and aetiological research. This study aimed to aggregate and analyze patterns of TA, excluding third molars, in individuals with DS using the tooth agenesis code (TAC). The study was designed as a secondary analysis, following STROSA guidelines. The search (MEDLINE-PubMed) and selection process resulted in six included studies encompassing 241 individuals with DS. TA data were systematically converted into TACs and analyzed per dentition, per jaw, and per tooth type. Symmetry was evaluated. The prediction was calculated for oligodontia. In the 155 cases with TA 86 distinct Overall-TAC patterns were identified. The most common patterns were bilateral maxillary lateral incisor agenesis (TAC002.002.000.000;10.3%), bilateral mandibular second premolar agenesis (TAC000.000.016.016;5.8%), and unilateral left maxillary lateral incisor agenesis (TAC000.002.000.000;5.2%). Symmetry in TA patterns was observed in 49.6% of TA cases in the maxilla and 52.3% in the mandible. The simultaneous absence of both mandibular central incisors had a large predictive value for oligodontia (OR12.44;95% CI:4.97-31.84; p<.001). Predominant TA patterns exist in DS. Observation of mandibular central incisor agenesis can promote early diagnosis of oligodontia in DS.

Agenesis of all premolars – the first reported case

Abstract The agenesis of teeth is the most common developmental anomaly in humans. Although third molars, mandibular second premolars, maxillary lateral incisors and maxillary second premolars are frequently found to be missing, the absence of all premolars has never been reported in the literature. This case report highlights the first-ever case of the complete agenesis of premolars in a 10-year-old male patient. It also discusses related definitions; commonly missing teeth and their prevalence; associated dental and skeletal features; genetic, drug-related and pathogenic etiological factors; and considerations for the future management of such cases.

Characterizing infraocclusion in primary molars: prevalence, accompanying findings, and infraocclusion severity and treatment implications

BackgroundThis manuscript investigates the prevalence, classification, accompanying findings, and treatment modalities associated with infraoccluded primary molars. The aim of this study categorizing primary molars based on the severity of infraocclusion and assessing their respective treatment interventions across different severity groups.MethodsThe classification, treatment types, accompanying findings, and the condition of succeeding premolars of infraoccluded molars were documented. Chi-square tests, including Fisher’s Exact Chi-square test, Fisher Freeman Halton Exact Chi-square test, and One Sample Chi-square test, were conducted. The predetermined significance level was less than 0.05.ResultsThe study population consisted of 3132 subjects aged 3 to 15 years, with a prevalence of 4.3% for infraocclusion. Infraocclusion typically manifests between 6 and 9 years of age and predominantly affects mandibular primary molars. Treatment interventions varied based on infraocclusion severity, with more invasive procedures required for severe cases. Accompanying findings associated with infraocclusion include adjacent teeth tipping, significant deviation in midline shifts towards the affected side and increased caries. Additionally, succeeding premolar agenesis was observed in 2% of infraoccluded molars, with extraction rates higher in cases where the successor tooth was mesially or distally located.ConclusionsThe study offers novel insights to dental practitioners concerning the severity and distribution of treatment interventions for infraocclusion. It suggests that more severe cases may necessitate more invasive procedures, with the aim of enhancing patient outcomes through timely intervention and personalized therapeutic strategies.

Prevalence, Severity, and Correlation with Agenesis of Permanent Successors of Infraoccluded Primary Molars at Chonnam National University Hospital’s Department of Pediatric Dentistry

This study aimed to analyze the prevalence and severity of infraoccluded primary molars (IPM) and their correlation with the agenesis of permanent successors (APS). A total of 4,011 panoramic radiographs from children aged 4 to 11 years who had all 8 primary molars were examined. The prevalence of APS was analyzed based on the severity and tooth type of IPM. The prevalence of IPM was 13.0%, and there was no difference between genders. The majority of the children had two IPMs each. In all tooth types, mild infraocclusion was the most prevalent, whereas severe infraocclusion was the least frequent. Among the types of primary molars, the lower primary first molar (62.3%) was the most affected, followed by the lower primary second molar (27.7%), the upper primary second molar (5.8%), and the upper primary first molar (4.2%). Infraocclusion was 11.2 times more prevalent in the mandible than in the maxilla, with no significant difference between the left and right sides. The correlation between IPM and APS was also investigated. Among the subjects, 177 had one or more agenesis of premolars, of whom 54 (30.5%) had IPM. Additionally, among the 521 individuals with IPM, 54 individuals exhibited APS (10.4%). This study identified a noteworthy prevalence of infraocclusion, with notable variations among molar types. The LPFM was particularly affected. The majority of cases were classified as mild in severity. Furthermore, a compelling association between IPM and APS was established. Understanding this connection may enhance treatment strategies for infraoccluded teeth and tooth agenesis.

Mandibular Second Premolar Agenesis: A Retrospective Cross-sectional Study from Palestine.

This retrospective study aimed to determine the prevalence of congenitally missing mandibular second premolars. A total of 1,843 radiographs were collected from five different cities in Palestine. Two experienced dentists independently examined the panoramic radiographs and demographic data (age and gender). Among the 1,843 radiographs, 1,039 were for females (57.37%) and 804 were for males (43.63%); 13 cases had at least one congenitally mandibular second premolar. The prevalence of congenitally missing mandibular second premolars in the study population was 0.7%. There was no significant association between gender and mandibular second premolar agenesis. Unilateral agenesis was more common than bilateral, and the left side had more cases of congenitally missing mandibular second premolars than the right side. The prevalence of congenitally missing mandibular second premolars in this study population was 0.7%, within the range reported in other populations.

Concomitant Existence of Tooth Agenesis (Agenesis of Four Second Premolars) and Supernumerary Tooth (Dens Distomolar)-Report of a Rarest Case

“Distomolar” is also called as ‘fourth molar’ is the supernumerary tooth occurring distal to the third molar. Occurrence of distomolar is a rare phenomenon. Along with this condition congenital agenesis which is a contrast phenomenon compared to extra teeth is still a rarer entity. Therefore, the aim of this paper is to present occurrence of fourth molar in the mandibular arch and congenital agenesis of all second premolars (four premolars) involving both maxillary and mandibular quadrant in a non-syndromic Indian female patient. Such combination of two different anomalies representing two different dental phenomenon is not reported till date according to author’s best of knowledge.

Mandibular second premolar distoangulation: a longitudinal follow-up from the mixed to the permanent dentition.

The aim of this study was to assess the frequency of mandibular second premolar (MnP2) distoangulation among orthodontic patients and the angular changes after a longitudinal follow-up. The sample was collected from the orthodontic records of 865 patients. The distoangulation group was composed of 42 patients (mean age 9.29 ± 1.24 years, 16 male, 26 female) with distoangulation of MnP2. The control group was composed of 32 patients (mean age 9.38 ± 1.10 years, 15 male, and 17 female) without distoangulation of MnP2. Panoramic radiographs taken in the mixed (T1) and the early permanent dentition (T2) were analyzed in both groups. Longitudinal angular changes (distal angle θ and premolar-molar angle γ), degree of root formation, second premolar depth, and prevalence of associated dental anomalies were analyzed. Intergroup comparison was performed with Mann-Whitney, t-tests, and chi-square tests (P < 0.05). The prevalence of MnP2 distoangulation in the mixed dentition was 4.85%. The distoangulation group showed a smaller initial distal angle (59.34o ± 8.41) when compared to control group (79.88o ± 7.60). The spontaneous eruption of the MnP2 with distoangulation was observed in 76.57% of the sample. MnP2 distoangulation was significantly associated with agenesis of its antimere, small maxillary lateral incisors, and deciduous molar infraocclusion. Severe cases of MnP2 distoangulation were absent in this study. The frequency of MnP2 distoangulation among orthodontic patients was 4.85%. Mild to moderate distoangulated Mnp2 spontaneously uprighted from the mixed to the permanent dentition. Small lateral incisors, second premolar agenesis, and infraocclusion of deciduous molar were frequently found in cases with MnP2 distoangulation.

Patterns of nonsyndromic tooth agenesis and sexual dimorphism

BackgroundSex dimorphism has been implicated in oral health differences and the pathogenesis of oral diseases, such as tooth agenesis, periodontal disease, dental caries, and tooth loss. Tooth agenesis (TA) is one of the most common developmental anomalies in humans, and its prevalence and patterns are different across ethnic groups. The aim of this study was to investigate the phenotypes and sex-associated patterns of nonsyndromic tooth agenesis (TA) in Thai dental patients.MethodsOne thousand ninety panoramic radiographs were examined. One hundred and one subjects (37 males, 64 females, 15–20 years-old) with nonsyndromic TA were evaluated. Differences in TA prevalence between groups were analyzed using the chi-square or Fisher exact test.ResultsThe TA prevalence, excluding third molars, was 9.3% and more frequently found in the mandible compared with the maxilla. The maxilla demonstrated a higher prevalence of first premolar agenesis than the mandible (P = 0.012), while the mandible had a higher prevalence of second premolar agenesis than the maxilla (P = 0.031). There were significantly more males missing one tooth than females, however, there were more females missing two or more teeth than males (P = 0.042). A missing maxillary left lateral incisor was significantly more frequent in males (P = 0.019), while a missing mandibular right lateral incisor was more frequent in females (P = 0.025). In females, the pattern of two mandibular lateral incisors agenesis was the most common and significantly present in females more than males (P = 0.015). In contrast, the pattern of one mandibular left lateral incisor agenesis was only observed in males and significantly found in males more than females (P = 0.047).ConclusionsWe demonstrate sex-associated differences in nonsyndromic tooth agenesis. The prevalence of single tooth agenesis was higher in males, while that of two or more teeth agenesis was higher in females. We found different patterns of lateral incisor agenesis between males and females.

Curve of Spee and Second Mandibular Premolar Agenesis—Present Knowledge and Future Perspectives

Background: We investigated the relationship between the mandibular Curve of Spee (COS) and a persisting primary second mandibular molar (ppM2) due to an agenesis of the second mandibular premolar, using a digital software technique. Methods: Digital dental casts were obtained from 200 patients at the Department of Orthodontics in Innsbruck and Vienna, Austria. Patients (age-, gender-, and malocclusion-matched) were equally divided into two groups (n = 100) according to the existence of a ppM2. COS depth, overjet, overbite, and angle-classification were measured digitally using the OnyxCeph3TM (version 3.2.147) software. ANOVA and Kruskal–Wallis tests were used to analyze relationships. For statistical analyses, p &lt; 0.05 was considered as statistically significant, p &lt; 0.01 as highly significant. Results were visualized with box plots and bar charts. Results: The deepest COS was present in patients with a ppM2. Furthermore, a positive correlation was shown between COS depth and angle-class II, between COS depth and age, as well as between COS depth and overbite. No gender differences could be observed. Conclusions: In our study population the COS depth was dependent on whether there is a ppM2 due to an agenesis of a second mandibular premolar or not, as well as on the malocclusion in sagittal direction.

Correlation of Dental Anomalies with Cleft Type and Gender in Non-Syndromic Oral Cleft Patients: A Cross-Sectional Study.

To investigate the distribution of dental anomalies between non-syndromic orofacial cleft patients and their association with the cleft type and gender. Retrospective cross-sectional study involving examination of intraoral dental records and radiographs. 300 non-syndromic orofacial cleft patients included (161 males and 139 females, mean age: 10.23 ± 2.3 years). Variables analyzed: tooth agenesis, microdontia, and supernumerary teeth. Data analysis: Chi-square and Fisher's exact tests to investigate the correlation between dental anomalies, cleft type, and gender. Agenesis occurred in 66% of the subjects, supernumerary teeth in 19.6%, and microdontia in 18.3%. In females with unilateral left cleft lip and palate (CLP), agenesis was significantly higher compared to males. Both genders presented significant agenesis of maxillary lateral incisors and right central incisor. Significant agenesis of central incisor, canine and second premolar on the upper left side and lower second premolars were observed only in males, with significant microdontia for maxillary lateral incisors and left central incisor. Significant agenesis of maxillary first premolars was seen only in females. Agenesis in maxillary quadrants was significant for patients with unilateral right and left CLP, and bilateral CLP. In mandibular quadrants, agenesis was substantially higher for patients with isolated CP. Results suggest that tooth agenesis and microdontia might not be directly associated with the cleft area's anatomical irregularity but are affected by gender and other genetic factors that regulate the development of the anomaly and the orofacial clefting mutually.

Infraocclusion level and root resorption of the primary molar in second premolar agenesis: A retrospective cross-sectional study in the Portuguese population.

Mandibular second premolar (M2P) agenesis results in the second primary molar (2pm) retention, infraocclusion, a reduced alveolar height and width, the supraeruption of antagonists, or the movement of the adjacent teeth. Infraocclusion affects the survival of the retained 2pm to a greater extent than root resorption. The aim of the study was to evaluate the lifespan of the primary molar as a substitute, with root quality and occlusal adaptation, in cases of M2P agenesis in a low-income population to determine if the attitude of just vigilance could be the best clinical option whenever other clinical problems are absent. A total of 12,949 orthopantomograms were analyzed. Sixty-one patients (25 males and 36 females aged 7–36 years) were divided into group 1 (the first permanent molar in occlusion) and group 2 (the second permanent molar also in occlusion). Vertical positioning to the occlusal plane, root condition and the movement of the adjacent teeth were evaluated. Despite the study having a cross-sectional design, root resorption, infraocclusion, the distance between the first permanent molar and the first primary molar or the first permanent premolar, and the width of the 2pm were correlated with age. The 2pm root resorption increased with age, which was more pronounced when the second permanent molar was also in occlusion. The mesial movement of the adjacent teeth was absent in all groups. The 2pm was often occluded, but infraocclusion increased with age. Age periods of 11–15 years and 21–25 years were critical for the primary tooth loss. The second primary molar remains functional in the mandibular arch for up to 25 years. A well-documented no-intervention attitude based on clinical and radiographic data must be weighed in cases without orthodontic issues or with financial constraints.

A 5-year randomized controlled trial comparing zirconia-based versus metal-based implant-supported single-tooth restorations in the premolar region.

ObjectiveTo compare 5‐year biological, technical, aesthetic, and patient‐reported outcomes of single‐tooth implant‐supported all‐ceramic versus metal‐ceramic restorations.Materials and methodsThirty patients with 63 premolar agenesis participated in the 5‐year follow‐up. The prosthetic treatment on single‐tooth implants was randomly assigned to all‐ceramic crowns on zirconia abutments (AC = 31) or metal‐ceramic crowns on metal abutments (MC = 32). All patients were recalled to clinical examinations at baseline, 1, 3, and 5 years after prosthetic treatments. Biological, technical, and aesthetic outcomes including complications were clinically and radiographically registered. The patient‐reported outcomes were recorded using OHIP‐49 questionnaire before treatment and at each follow‐up examination.ResultsAt the 5‐year examination, the survival rate was 100% for implants and 100% for AC and 97% for MC crowns and abutments. The marginal bone loss after 5 years was minor and not significantly different (p = .056) between AC (mean: 0.3, SD: 1.1) and MC (mean: −0.1, SD: 0.4) restorations. The success rate of the implants based on marginal bone loss was 77.4% for AC‐ and 93.7% for MC restorations. The marginal adaptation was significantly better for MC than for AC restorations (p = .025). The aesthetic outcomes and patient‐reported outcomes between AC and MC restorations were not significantly different.ConclusionsThe biological, aesthetic and patient‐reported outcomes for implant‐supported AC and MC restorations were successful and with no significant difference after 5‐years. The marginal adaptation of the MC crowns cemented on titanium abutments showed a significantly better fit than restorations based on zirconia crowns cemented on zirconia abutments.

Bireylerde mandibular ikinci premolar eksikliğinin prevalansı ve ilişkili faktörler: meta-analiz çalışması

Background: The purposes of this study were to determine the prevalence and patterns of mandibular second premolar agenesis in individuals by meta-analysis methodology.Methods: Two investigators conducted a literature search independently by inclusion criteria to reveal articles on mandibular second premolar agenesis. PubMed, Google Scholar, Ovid Medline, Web of Science Core Collection databases were scanned and a total of 3,988 studies were initially extracted from all databases, then 12 articles were selected which met inclusion and exclusion criteria for the meta-analysis.Results: The estimated overall prevalence of mandibular second premolar in individuals was 3.26 %. No statistically significant difference was found in the prevalence of mandibular second premolar agenesis by gender [95 % Cl: 1.18 (0.96, 1.45); p&amp;gt;0.05]. Males were found to have a significantly higher prevalence of unilateral mandibular second premolar agenesis than females (combined OR 0.69; 95 % CI: 0.38-1.25; p&amp;lt;0.05). However, females had a significantly higher prevalence of bilateral mandibular second premolar agenesis than males (combined OR 1.57; 95 % Cl: 0.91-2.72; p&amp;lt;0.05). No difference was found in the prevalence of mandibular second premolar agenesis between the right and left mandibular region [95 % Cl: 1.04 (0.91-1.20); p&amp;gt;0.05].Conclusion: This study supports some previous findings regarding mandibular second premolar agenesis and presents new observations on gender differences, inter-maxillary patterns of mandibular second premolar agenesis in the mandible—including unilateral and/or bilateral occurrence and jaw site.

Dental formula variations in wild and domestic Sus scrofa: is the first premolar agenesis an evolutionary trend?

Abstract We investigated the occurrence of congenital dental abnormalities in 94 wild boars Sus scrofa scrofa, and 20 Iberian pigs Sus scrofa domesticus from Doñana (DNP) and Sierra de Andújar Natural Park (ANP) southern Spain. The only dental variation found was agenesis of the lower first premolar, either deciduous (Dp1) or permanent (P1). We analyzed prevalence variations using: odds ratios, Fisher’s exact test and logistic-regression models. The lower first premolar has often been reported to be absent in modern domestic breeds of pigs, but it is usually reported as present in wild boar. However, we found a similar occurrence of agenesis in wild boar as in Iberian pigs. A common genotypic background between wild boar and Iberian pig populations of ANP sharing the same ecosystems may explain this result. When considering only wild boar, unexpected differences between populations were detected. The wild boar from ANP showed higher estimated probabilities of agenesis than those from DNP. Environmental conditions can also represent influencing factors for changes within subspecies. Our findings reinforce the idea that in suids the congenital absence of premolars probably has an evolutionary relevance, which could represent a generalized trend towards the reduction of the dental formula from the plesiomorphic placental dentition.

Prevalence of dental anomalies in different cleft lip and palate groups

Introduction: Patients with orofacial clefts are usually associated with various dental anomalies. These dental aberrations pose a clinical challenge in treatment planning. Thus, this investigation intends to find the prevalence rate of different types of dental anomalies and their correlation among nonsyndromic cleft patients. Methodology: Orthodontic records of 129 cleft patients classified into different cleft groups were assessed to evaluate the presence of different dental anomalies. Results: The most frequent dental anomaly found in Cleft patients was rotations followed by maxillary lateral incisor agenesis with a prevalence rate of 90.4% and 59.2%, respectively. Maxillary second premolar agenesis, peg-shaped laterals, mandibular second premolar agenesis, and supernumerary teeth showed prevalence rates as 25%, 21%, 7%, and 5%, respectively. There were significant differences in the overall distribution of maxillary lateral incisor agenesis and rotations between patients with Unilateral Cleft Lip and Cleft Palate, Bilateral Cleft Lip and Cleft Palate, Cleft Lip (CL), and Isolated Cleft Palate (ICP). Conclusion: There is a high prevalence of dental anomalies like rotations and maxillary lateral incisor agenesis in different CL and palate patients, which were statistically significant. The presence of such anomalies can deteriorate the already existing functional problem and hence, the study of these anomalies and their treatment is an important step in the rehabilitation of such patients.

Posterior rehabilitation using 3D-printed dental implants and synthetic regenerative membranes

Aim: To describe through a clinical case report the surgical sequence of rehabilitation with 3D-printed implantsassociated with maxillary sinus floor lift with synthetic regenerative materials, including biphasic bioceramic.Case Report: Patient had an agenesis of the upper left premolars (#12 and #13), a vertical bone deficiencycaused by maxillary sinus’ pneumatization, and a horizontal alveolar resorption around the missing teeth area.During the surgical procedures, incisions, detachment, and osteotomy were performed in the lateral region ofthe maxillary sinus. The sinus membrane was detached and lifted 10 mm. Then, a thick poly(dioxanone)-basedsynthetic resorbable membrane (Plenum) was inserted and adapted inside the sinus to protect the sinus membrane.After the osteotomies with sub-instrumentation, 3D-printed implants (Plenum) were installed in the #12 area(3.5mm x 11.5 mm; 30N) and #13 area (4.0mm x 10mm; 20N). The maxillary sinus was entirely filled with abiphasic bioceramic,HA/B-TCP (70:30) 500-1000 um (Plenum) and covered by the same synthetic resorbablemembrane. Connective tissue graft from the palatal area was positioned internally to the flap and stabilized withsutures to improve the vestibular tissue architecture. The entire surgical wound was sutured, and the tissuesstabilized. No complications occurred in the postoperative period. Conclusion: The use of synthetic regenerativememberane and 3D-printed implants seems to be a promising option in areas of deficient bone remnants. KEYWORDSDental Implants; 3D Printing; Maxillary Sinus; Sinus Floor Augmentations; Tissue Grafting.

A Genome-wide association study of premolar agenesis in a chinese population.

Premolar agenesis is a common subtype of tooth agenesis. Although a genome-wide study (GWAS) has identified some variants involved in tooth agenesis in Europeans, the genetic mutation related to premolar agenesis in the Chinese population remains unclear. We present a GWAS in 218 premolar agenesis cases and 1,222 controls using the Illumina Infinium® Global Screening Array. 5,585,618single nucleotide polymorphisms (SNPs) were used for tests of associations with premolar agenesis. Four independent SNPs on chromosome 2 were identified as susceptibility loci, including rs147680216, rs79743039, rs60540881, and rs6738629. The genome-wide significant SNP rs147680216 (p=6.09×10-9 ) was predicted to change the structure of the WNT10A protein and interact with hedgehog signaling pathway components. Meta-analysis showed that the rs147680216 A allele significantly increased the risk of tooth agenesis (p=0.000). The other three SNPs with nominal significance are novel susceptibility loci. Of them, rs6738629 (p=5.40×10-6 ) acts as a potential transcriptional regulator of GCC2, a gene playing a putative role in dental and craniofacial development. Our GWAS indicates that rs147680216 and additional three novel susceptibility loci on chromosome 2 are associated with the risk of premolar agenesis in the Chinese population.