Morphological analysis of cementoenamel junction in premolars of Sri Lankans.

Cementoenamel junction is an anatomical landmark which indicates the meeting point of enamel of the crown and the cementum of the root. It is an important reference point in clinical dentistry as well as in dental radiography. The present study is done to describe the distribution of the mineralized tissue at the cementoenamel junction in relation to various surfaces of the premolars. The study sample consisted of 89 permanent maxillary and mandibular premolars from both males and females extracted for orthodontic reasons. They were stained with carbol fuchsin and observed under a dissecting microscope to identify the following tissue interrelationships at the cementoenamel junction: cementum overlapping the enamel; edge-to-edge relationship between enamel and cementum; gap between the enamel and cementum and enamel overlapping the cementum. The cementum overlapping the enamel interrelationship was predominant in the buccal and lingual surfaces of both first and second maxillary premolars, while the edge-to-edge relationship and the presence of a gap between the enamel and the cementum relationship were abundant in distal and mesial sides. Enamel overlapping the cementum was recorded only in a very small proportion of the sample. A good understanding about the morphological variations at the cementoenamel junction area is very important and this area should be handled carefully during routine dental procedures such as dental bleaching, orthodontic treatment, placement of rubber dam and placement of dental materials.

The dimension and morphology of alveolar bone at maxillary anterior teeth in periodontitis: a retrospective analysis-using CBCT.

The morphology of the alveolar bone at the maxillary anterior teeth in periodontitis patients was evaluated by cone-beam computed tomography (CBCT) to investigate the distribution of alveolar defects and provide guidance for clinical practice. Ninety periodontitis patients and 30 periodontally healthy individuals were selected to determine the morphology of the alveolar bone at the maxillary anterior teeth according to the degree of bone loss, tooth type, sex and age. The differences in the dimensions between periodontitis patients and healthy individuals were compared, and the distribution of alveolar bone defects was analyzed. A classification system was established regarding the sagittal positions and angulations of the teeth. The buccal residual bone was thicker and the lingual bone was thinner in the periodontitis patients than in the periodontally healthy individuals, and there were differences between the different tooth types, sexes and age subgroups. The buccal undercut was close to the alveolar ridge, while fenestration was reduced and the apical bone height was higher in periodontitis patients than in periodontally healthy individuals. The apical bone height increased with the aggravation of bone loss and age. The proportions of different sagittal positions changed with the aggravation of bone loss. Moreover, the teeth moved more buccally regarding the positions of the maxillary anterior teeth. The morphology of the alveolar bone at the maxillary anterior teeth differed between periodontitis patients and healthy individuals, and the differences were related to the degree of bone loss, tooth type, sex and age.

Swept-source optical coherence tomographic observation on prevalence and variations of cemento-enamel junction morphology.

To investigate the prevalence of different patterns of cemento-enamel junction (CEJ) morphology under swept-source optical coherence tomography (SS-OCT). One hundred extracted human teeth were used consisting of incisors, premolars, and molars. Each sample was observed for every 500 µm circumferentially along CEJ and OCT images of the pattern were noted. Microscopic observations were done for the representative sample using confocal laser scanning microscope (CLSM) and transmission electron microscope (TEM). The OCT images exhibited four CEJ patterns: edge-to-edge (type I), exposed dentin (type II), cementum overlapping enamel (type III), and enamel overlapping cementum (type IV). The prevalence of CEJ patterns was further statistically considered for mesial, distal, buccal, and lingual surfaces. The real-time imaging by SS-OCT instantly determined CEJ morphology. CLSM and TEM observation revealed morphological features along CEJ, which corresponded to OCT images of CEJ anatomy. OCT results showed 56.8% of type I pattern predominantly found on proximal surfaces, followed by 36.5% of type II pattern on buccal and lingual surface, 6.4% of type III pattern, and 0.3% of type IV pattern. There was a significant difference in prevalence of CEJ patterns among different types of teeth, but there was no statistically significant difference among the four surfaces in each type of teeth. OCT is a non-invasive diagnostic tool to examine the CEJ patterns along the entire circumference. OCT observation revealed even minor dentin exposure that would need clinical and home procedures to prevent any symptoms.

Morphological Analysis Of Cementoenamel Junction Types In Premolars And Molars Of A Sample Of Pakistani Population.

BACKGROUND: Cementoenamel junction represents the demarcation between enamel covered crown and cementum covered root surface. There is paucity of population specific data of the morphological variability of cementoenamel junctions of permanent and primary teeth. The objective of this study was to investigate the morphological diversity and interrelationship of cementoenamel junction of premolar and molar teeth in permanent dentition of a sample of Pakistani population with potential forensic and anthropological implications. METHODS: This cross-sectional study was conducted at Oral Biology department of Dr Ishrat ul Ebad khan institute of oral health science, Dow University from March till September 2016. Seventy-five maxillary and mandibular permanent premolar and molars from adult patients of both sexes were selected and sectioned. Longitudinal ground sections were prepared to study the morphological interrelationship between Cementum and Enamel in each specimen to be viewed under light microscope. A chi-square test was applied between the categorical variables. RESULTS: Results showed 57.3% of sections had cementum overlapping enamel interrelation, 32% showed edge to edge cementum and enamel relation and 9.3% showed that cementum and enamel failed to meet resulting in exposed dentine, while 1.3% sample showed enamel over cementum relation. No significant correlation was found between gender, type of tooth, maxillary, mandibular arches and the morphological variation of CEJ (p>0.05). CONCLUSIONS: It can be concluded that there are considerable morphological variations in CEJ of premolars and molars with preponderance of cementum overlapping enamel in these teeth. Based on these findings, dentists are advised to be mindful of dental procedures involving the CEJ and that these interventions should be performed meticulously avoiding any detachment of cementum and subsequent exposure of dentin resulting in dentin hypersensitivity.

Piezocorticision-assisted orthodontics: Efficiency, safety, and long-term evaluation of the inflammatory process.

OBJECTIVES: The aim of this work was to compare the duration of treatment between orthodontic treatment combined with piezocorticision (OT-PC) and conventional orthodontic treatment (COT), as well as to evaluate the safety, inflammatory process, periodontal health, and soft tissue healing in the OT-PC group. METHODS: Twelve patients were included in each group, and their treatment times were compared for preliminary bracket alignment (PBA) and for overall treatment. In the OT-PC group, the inflammatory process was evaluated by quantifying cytokines in the gingival crevicular fluid. A calibrated examiner measured the probing depth (PD), the distance between the gingival margin and the cementoenamel junction (GM-CEJ), and the clinical attachment level (CAL), before and after OT-PC. The presence of gingival scars was evaluated. Bone and root injuries were assessed with the use of cone-beam computed tomography. RESULTS: The treatment time was significantly reduced in the OT-PC group for PBA in both maxilla (45%; P = 0.001) and mandible (31%; P = 0.023), as well as for overall treatment (52%; P < 0.0001). Although not statistically significant, several inflammatory mediators demonstrated peaks at 3-5 and 16 weeks. There were not significant changes in PD and GM-CEJ after OT-PC treatment, unlike CAL (0.09 ± 0.12 mm; P = 0.024); 47.5% of piezocorticisions caused gingival scars. Only one patient showed no scars. Four cortical bones did not heal completely, and 2 roots had piezoelectric injuries. CONCLUSION: OT-PC was effective at reducing the orthodontic treatment time.

Correlation between buccal and alveolar bone widths at the central incisors according to cone-beam-computed tomography.

OBJECTIVE: The aim of this study is to assess whether there is a correlation between buccal bone thickness and mean alveolar bone thickness around the central teeth using CBCT images. MATERIALS AND METHODS: Three points were selected at 3, 6 and 9 mm from the cemento-enamel junction, respectively, perpendicular to the long axis of the measuring points made to determine the width of the alveolar bone ridge. The arithmetic mean of the length measurements was taken as the average alveolar bone thickness. To determine the average buccal alveolar bone thickness, the buccal bone length was measured perpendicular to the long axis of the tooth from these 3 points, and the average of the measurements was taken from these 3 points. RESULTS: The mean coronal, mid-root, and apical third root widths of the maxillary, left central incisors were 7.72±0.60, 8.64 ± 0.93, and 9.23±1.45 mm, respectively and the mean widths of the buccal alveolar bone at the coronal, mid-root, and apical third root positions of the left central incisor were 1.18±0.39, 1.15±0.44, and 1.06±0.50 mm, respectively. The Spearman correlation coefficients were 0.194 and 0.191 for the left and right central incisors, respectively. CONCLUSIONS: There was no statistically significant difference between the alveolar bone thickness averages of the left and right central incisors, but the alveolar bone thickness was found to be thicker in males than females. Although the mean of alveolar and buccal bone thicknesses was positively correlated the statistical analysis demonstrated the correlation between the mean of alveolar and buccal bone thicknesses is not significant.

A cone-beam computed tomography study of the mesial cervical concavity of maxillary first premolars.

OBJECTIVE: To investigate the mesial cervical concavity of maxillary first premolars and its relationship with root and canal configuration using cone-beam computed tomography (CBCT). DESIGN: Images of maxillary first premolars (n = 1056) were collected from patients (n = 601) who had undergonein vivo CBCT scanning. The root and canal number and morphology were evaluated. The following measurements of the mesial cervical concavity of the maxillary first premolars were evaluated in section images: dentine thickness (in concavity at the cemento-enamel junction), concavity angle, depression depth (distance from mesial dentinal surface at concavity to mesial proximity), concavity position (distance from mesial dentinal wall at invagination to the top of the mesial marginal ridge). The reliability of the data was analyzed with an unpaired Student's t test and Fisher's exact test. RESULTS: The percentages of maxillary first premolars with one root, two, and three roots were 55.5%, 43.7%, and 0.8% respectively. Mesial cervical concavity was recorded in 64.5% of single-root maxillary premolars. The prevalence of two-root maxillary first premolars with mesial cervical concavity was 73.8%. The means of the aforementioned four measurements were 1.705, 147.9, 1.640, and 5.247 mm. The values of dentine thickness (mm), depression depth (mm), and concavity position (mm) of the mesial cervical concavity were largest in two-root maxillary first premolars. The smallest concavity angle of the mesial cervical concavity was found in three-root maxillary first premolars. CONCLUSIONS: There is a high prevalence of mesial cervical concavity among maxillary first premolars. The mesial root concavity is more prevalent in single-rooted maxillary first premolars when there are two canals present, and its prevalence and degree of concavity increase with the number of roots.

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

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

Bone and cortical bone thickness of mandibular buccal shelf for mini-screw insertion in adults.

OBJECTIVE: To analyze the buccal bone thickness, bone depth, and cortical bone depth of the mandibular buccal shelf (MBS) to determine the most suitable sites of the MBS for mini-screw insertion. MATERIALS AND METHODS: The sample included cone-beam computed tomographic (CBCT) records of 30 adult subjects (mean age 30.9 ± 7.0 years) evaluated retrospectively. All CBCT examinations were performed with the i-CAT CBCT scanner. Each exam was converted into DICOM format and processed with OsiriX Medical Imaging software. Proper view sections of the MBS were obtained for quantitative and qualitative evaluation of bone characteristics. RESULTS: Mesial and distal second molar root scan sections showed enough buccal bone for mini-screw insertion. The evaluation of bone depth was performed at 4 and 6 mm buccally to the cementoenamel junction. The mesial root of the mandibular second molar at 4 and 6 mm showed average bone depths of 18.51 mm and 14.14 mm, respectively. The distal root of the mandibular second molar showed average bone depths of 19.91 mm and 16.5 mm, respectively. All sites showed cortical bone depth thickness greater than 2 mm. CONCLUSIONS: Specific sites of the MBS offer enough bone quantity and adequate bone quality for mini-screw insertion. The insertion site with the optimal anatomic characteristics is the buccal bone corresponding to the distal root of second molar, with screw insertion 4 mm buccal to the cementoenamel junction. Considering the cortical bone thickness of optimal insertion sites, pre-drilling is always recommended in order to avoid high insertion torque.

Assessment of gingival biotype and facial hard/soft tissue dimensions in the maxillary anterior teeth region using cone beam computed tomography.

OBJECTIVE: This study sought to assess the relationship between facial gingival and bone dimensions in maxillary anterior teeth region using cone beam computed tomography (CBCT). DESIGN: This study assessed 621 maxillary anterior teeth in 144 patients. In the sagittal plane, facial bone thickness (BT) and gingival thickness (GT) were measured at the crestal level and at 2, 4 and 6mm apical to the cementoenamel junction (CEJ). The dentogingival complex (DGC) dimensions and the distance from the CEJ to bone crest were also measured on CBCT scans. To determine the gingival biotype, GT at 2mm apical to the gingival margin was measured and GT <1.5mm was categorized as thin while GT ≥1.5mm was categorized as thick. The data were analyzed using SPSS version 21 via repeated measures ANOVA and the Cochrane's Q, chi-square and independent samples t-tests. RESULTS: The BT around the maxillary central and lateral incisors and canine teeth at 4 and 6mm apical to the CEJ was significantly different in thick and thin gingival biotypes (P<0.05). The mean GT at 2 and 4mm apical to the CEJ was significantly different around central and lateral incisors (P<0.05). Thickness of crestal bone was significantly different between the two gingival biotypes around central and lateral incisors (P<0.05). CONCLUSION: The two gingival biotypes had significantly different mean BT; different biotypes and their relationship to BT varied around anterior maxillary teeth.

[Classification of the anatomical structures of maxillary central incisor root by cone-beam CT].

Objective: To examine the root position of the maxillary central incisors and to provide clinical reference before the immediate implant placement. Methods: Cone-beam CT (CBCT) data of the maxillary central incisors of 934 patients (934 incisors) was selected and the root position classsified. The sagittal root position in the alveolar bone was classified as buccal, middle, or palatal. The buccally positoined type was further classified into three subtypes of Ⅰ,Ⅱ, and Ⅲ. Results: Most of the maxillary incisor root (95.4% [891/934]) was positioned buccally. Among the buccal-type incisors, the subtypes Ⅰ, Ⅱ and Ⅲ accounted for 47.5% (423/891), 44.2% (394/891), and 8.3% (74/891). In the 4 mm apical to the cemento-enamel junction and the middle of the root, the thickest buccal bone wall was 0.86 and 0.95 mm, the thickest palatal bone wall was 1.65 and 2.37 mm. In the apical location, the thickest buccal bone wall was 1.89 mm, the thickest palatal bone wall was 7.83 mm. Conclusions: Most of the maxillary central incisors studied are positioned buccally, and half of these patients have adequate buccal bone and are suitable for immediate implant placement.

An In-VitroEvaluation of Microleakage at the Cervical Margin Between two Different Class II Restorative Techniques Using Dye Penetration Method.

OBJECTIVE: To evaluate the coronal microleakage of packable composite using conventional incremental and posterior bulk fill flowable composite using Smart Dentine Replacement Single Step technique in the cervical margins of class II cavities in dentine using the dye penetration method. STUDY DESIGN: In-vitroInterventional study. PLACE AND DURATION OF STUDY: Department of Operative Dentistry, Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences (DIKIOHS), Karachi, from November 2012 to April 2013. METHODOLOGY: One hundred and twenty extracted teeth (molars and premolars) were collected and randomly divided into two experimental groups (n=60 each) and were stored in normal saline until used. Fractured samples were excluded. Standardized class II proximal box only cavities were prepared and restored with conventional methacrylate based composite using incremental technique (Group A, n=40) and low stress methacrylate resin based composite SDR using single step technique (Group B, n=40). Samples were sectioned horizontally below the cervical margins and specimen disks were prepared. The specimens were thermocycled and sealed with acid resistant varnish leaving a 1-mm interface around cervical margin and immersed in 2% methylene blue buffered solution for 24 hours. Leakage was scored 0 - 4 and measured in mm. It washed and sectioned to evaluate under stereomicroscope. RESULTS: Mean penetration was 2.4280 ±0.79 mm for Group Aand 1.015 ±0.45 mm for Group B (p < 0.001). Maximum dye penetration score for group Awas 4 and group B was 3. CONCLUSION: SDR technique in combination with total etch technique at the cervical margin of class II restorations improved the marginal seal, when were placed in dentine and thermocycled.

Three-dimensional evaluation of root dimensions and alveolar ridge width of maxillary lateral incisors in patients with unilateral agenesis.

BACKGROUND: The objective of this retrospective case-control study was to measure the maxillary lateral incisor root dimensions and quantify the labial and palatal bone in patients with unilateral maxillary lateral incisor agenesis (MLIA) after orthodontic treatment and compare them to non-agenesis controls using cone beam computed tomography. METHODS: The labiopalatal and mesiodistal root dimensions, mesiodistal coronal dimensions, and labiopalatal bone and alveolar ridge widths of the maxillary lateral incisor were assessed on posttreatment cone beam computed tomography scans of 15 patients (mean age 16.5 ± 3.4 years, 9 females and 6 males) with maxillary lateral incisor agenesis and 15 gender-matched patients (mean age 16.08 ± 3.23 years) with no dental agenesis or anterior Bolton discrepancy. The Mann-Whitney test was used to distinguish any differences in root width, crown width, or changes in labial or palatal bone width between the two groups. RESULTS: The median labiopalatal root width was narrower in the MLIA group at the level of the cementoenamel junction (CEJ) to 8 mm apical of the CEJ compared to controls (p ≤ 0.009). The mesiodistal root width was significantly reduced in the MLIA group at the CEJ and at 4 mm apical to the CEJ. The labiopalatal alveolar ridge width was significantly decreased at 2 mm apical to the CEJ in MLIA group. The mesiodistal crown width was significantly smaller in the MLIA group at both the incisal edge and at the crown midpoint. The bone thickness was similar in both groups. CONCLUSIONS: Coronal and root dimensions in patients with MLIA were reduced compared to controls. Alveolar ridge width was also reduced in patients with MLIA, although bone thickness was not different than controls.

Evaluation of the In Vitro Effects of Cervical Marginal Relocation Using Composite Resins on the Marginal Quality of CAD/CAM Crowns.

PURPOSE: To evaluate the effect of cervical margin relocation (CMR) for crowns designed using CAD/CAM technology, and made of pre-cured resin or lithium disilicate, before and after thermomechanical loading. The test hypothesis was that the marginal quality of the crowns would not be influenced by the CMR with composite resins before or after thermomechanical loading. MATERIALS AND METHODS: Standard crown preparations were created in 40 human molars. The margins were located in enamel, except for the mesial proximal box, where the cervical margin was 2.0 mm below the cementoenamel junction, with 4.0 mm in the buccolingual and 2.0 mm in the mesiodistal dimension. For the CMR technique, a 2-mm layer of conventional or flowable composite resin was applied to the mesial box. Using the Cerec CAD/CAM system, 40 standard crowns were prepared, and restorations were luted using a dual-curing adhesive cement. SEM analysis was performed using epoxy resin replicas before and after loading to assess the marginal quality of interfaces of the mesial proximal box with CMR/crown and the distal face of the tooth without CMR. Statistical differences between groups were analyzed using the Kruskal-Wallis test and Bonferroni's post-hoc test. RESULTS: The null hypothesis was accepted, since no statistically significant differences were found in marginal quality before and after thermomechanical cycling (p > 0.05). CONCLUSION: The implementation of CMR before and after thermomechanical cycling had no effect on the quality of cervical margins. To establish whether CMR is a suitable procedure for the adhesive luting of composite resin crowns in deep proximal boxes, additional studies are required.

An attempt to predict tooth crown height using cementoenamel junction diameters and implications in the quantitative study of dental wear.

SUMMARY: Dental wear has been used extensively in osteoarchaeological studies as a means of exploring dietary patterns and the use of teeth as tools. The present paper aims to test whether crown height can be predicted for premolars and molars based on the mesiodistal and buccolingual diameters of these teeth at the level of the cementoenamel junction (CEJ). Multiple linear regression was used with crown height as dependent variable and diameters at the CEJ as predictors. Our results found that there are cases where the impact of one predictor appears to be statistically significant. However, even in these cases the 95% confidence interval for the predicted value is so broad that makes the accurate determination of the crown height based on the buccolingual or/and mesiodistal diameters at the CEJ impossible.

Influence of cervical preflaring on apical transportation in curved root canals instrumented by reciprocating file systems.

BACKGROUND: The aim of this study was to evaluate the influence of cervical preflaring on apical transportation in curved root canals prepared using the Reciproc and WaveOne reciprocating file systems. METHODS: Sixty curved canals were instrumented using Reciproc R25 and WaveOne Primary files, with and without preflaring (n = 15). A double-digital technique was used to digitally superimpose the file before instrumentation (#15 K-file) on the final apical reciprocating file (#25/08). The angle between the tip of the initial and final file was measured and recorded. Groups were compared using the Kruskal-Wallis test, and significance was set at p < 0.05. RESULTS: The mean and standard deviation for apical transportation was 0.93 ± 2.48 for the Reciproc Group, 0.84 ± 1.94 for the Preflaring + Reciproc Group, 0.40 ± 1.14 for the WaveOne Group, and 0.83 ± 2.20 for the Preflaring + WaveOne Group. No statistically significant differences were found among the groups (p = 0.9509). CONCLUSIONS: Under the conditions of this study, cervical preflaring did not influence apical transportation in curved root canals instrumented using Reciproc R25 and the WaveOne Primary files. Based on the in vitro measurements of apical transportation, the reciprocating files may be used without preflaring in curved root canals.

Identification of Apical and Cervical Curvature Radius of Human Molars.

To determine the frequency of apical and cervical curvatures in human molars using the radius method and cone-beam computed tomography (CBCT) images. Four hundred images of mandibular and maxillary first and second molars were selected from a database of CBCT exams. The radius of curvature of curved root canals was measured using a circumcenter based on three mathematical points. Radii were classified according to the following scores: 0 - straight line; 1 - large radius (r > 8 mm, mild curvature); 2 - intermediate radius (r > 4 and r < 8 mm, moderate curvature); and 3 - small radius (r ≤ 4 mm, severe curvature). The frequency of curved root canals was analyzed according to root canal, root thirds, and coronal and sagittal planes, and assessed using the chi-square test (significance at α = 0.05). Of the 1,200 evaluated root canals, 92.75% presented curved root canals in the apical third and 73.25% in the cervical third on coronal plane images; sagittal plane analysis yielded 89.75% of curved canals in the apical third and 77% in the cervical third. Root canals with a large radius were significantly more frequent when compared with the other categories, regardless of root third or plane. Most root canals of maxillary and mandibular first and second molars showed some degree of curvature in the apical and cervical thirds, regardless of the analyzed plane (coronal or sagittal).

Identification of Apical and Cervical Curvature Radius of Human Molars

To determine the frequency of apical and cervical curvatures in human molars using the radius method and cone-beam computed tomography (CBCT) images. Four hundred images of mandibular and maxillary first and second molars were selected from a database of CBCT exams. The radius of curvature of curved root canals was measured using a circumcenter based on three mathematical points. Radii were classified according to the following scores: 0 - straight line; 1 - large radius (r>8 mm, mild curvature); 2 - intermediate radius (r>4 and r<8 mm, moderate curvature); and 3 - small radius (r≤4 mm, severe curvature). The frequency of curved root canals was analyzed according to root canal, root thirds, and coronal and sagittal planes, and assessed using the chi-square test (significance at α=0.05). Of the 1,200 evaluated root canals, 92.75% presented curved root canals in the apical third and 73.25% in the cervical third on coronal plane images; sagittal plane analysis yielded 89.75% of curved canals in the apical third and 77% in the cervical third. Root canals with a large radius were significantly more frequent when compared with the other categories, regardless of root third or plane. Most root canals of maxillary and mandibular first and second molars showed some degree of curvature in the apical and cervical thirds, regardless of the analyzed plane (coronal or sagittal).

Determinar a frequência de curvaturas apicais e cervicais em molares humanos usando o método do raio de curvatura e imagens de Tomografia Computadorizada de Feixe Cônico (TCFC). Quatrocentas imagens de primeiros e segundos molares superiores e inferiores foram selecionadas a partir de um banco de dados de exames de TCFC. O raio de curvatura dos canais foi medido usando um circuncentro com base em três pontos matemáticos e classificado de acordo com os seguintes escores: 0 - linha reta; 1 - raio grande (r > 8 mm, curvatura suave); 2 - raio intermediário (r > 4 e r < 8, curvatura moderada); 3 - raio pequeno (r ≤ 4 mm, curvatura severa). A frequência de curvaturas foi analisada em função do canal radicular, dos terços da raiz, e dos planos de avaliação (coronal e sagital); e avaliados usando o teste Qui-Quadrado (significância de α=0.05). Dos 1200 canais radiculares avaliados, 92,75% apresentaram curvatura no terço apical e 73,25% no terço cervical quando da análise no plano coronal; a análise do plano sagital revelou 89,75% de canais curvos no terço apical e 77% no terço cervical. Canais radiculares com curvatura suave foram significantemente mais frequentes quando comparados com as demais categorias, independentemente do terço radicular ou do plano. A maioria dos canais radiculares dos primeiros e segundos molares superiores e inferiores apresentou algum grau de curvatura nos terços apical e cervical, independentemente do plano analisado (coronal ou sagital).

An Update on Crown Lengthening. Part 2: Increasing Clinical Crown Height to Facilitate Predictable Restorations.

This is the second paper in this two-part series. Paper one provided an overview of managing gingival tissue excess and paper two will focus on increasing clinical crown height to facilitate restorative treatment. Crown lengthening is a surgical procedure aimed at the removal of gingival tissue with or without adjunctive bone removal. The different types of procedure undertaken will be discussed over the two papers. In order to provide predictable restorations, care must be taken to ensure the integrity of the margins. If this is not taken into account it can lead to an impingement on the biologic width, which may in turn lead to chronic inflammation resulting in recession or the development of periodontal problems which can be hard to manage. Clinical Relevance: This paper aims to reinforce the need for thorough diagnosis and treatment planning and provides an overview of the various procedures that can be undertaken.

Changes of Root Length and Root-to-Crown Ratio after Apical Surgery: An Analysis by Using Cone-beam Computed Tomography.

INTRODUCTION: Apical surgery is an important treatment option for teeth with post-treatment periodontitis. Although apical surgery involves root-end resection, no morphometric data are yet available about root-end resection and its impact on the root-to-crown ratio (RCR). The present study assessed the length of apicectomy and calculated the loss of root length and changes of RCR after apical surgery. METHODS: In a prospective clinical study, cone-beam computed tomography scans were taken preoperatively and postoperatively. From these images, the crown and root lengths of 61 roots (54 teeth in 47 patients) were measured before and after apical surgery. Data were collected relative to the cementoenamel junction (CEJ) as well as to the crestal bone level (CBL). One observer took all measurements twice (to calculate the intraobserver variability), and the means were used for further analysis. The following parameters were assessed for all treated teeth as well as for specific tooth groups: length of root-end resection and percentage change of root length, preoperative and postoperative RCRs, and percentage change of RCR after apical surgery. RESULTS: The mean length of root-end resection was 3.58 ± 1.43 mm (relative to the CBL). This amounted to a loss of 33.2% of clinical and 26% of anatomic root length. There was an overall significant difference between the tooth groups (P < .05). There was also a statistically significant difference comparing mandibular and maxillary teeth (P < .05), but not for incisors/canines versus premolars/molars (P = .125). The mean preoperative and postoperative RCRs (relative to CEJ) were 1.83 and 1.35, respectively (P < .001). With regard to the CBL reference, the mean preoperative and postoperative RCRs were 1.08 and 0.71 (CBL), respectively (P < .001). The calculated changes of RCR after apical surgery were 24.8% relative to CEJ and 33.3% relative to CBL (P < .001). Across the different tooth groups, the mean RCR was not significantly different (P = .244 for CEJ and 0.114 for CBL). CONCLUSIONS: This CBCT-based study demonstrated that the RCR is significantly changed after root-end resection in apical surgery irrespective of the clinical (CBL) or anatomic (CEJ) reference levels. The lowest, and thus clinically most critical, postoperative RCR was observed in maxillary incisors. Future clinical studies need to show the impact of resection length and RCR changes on the outcome of apical surgery.