Estimating the occurrence of labial bone perforation and implantation into the maxillary sinus maxillary premolars based on the morphology of maxillary premolars: A clinical study.

STATEMENT OF PROBLEM: Previous studies have classified the sagittal root position of the maxillary anterior teeth and measured buccal plate thickness to aid treatment planning. A thin labial wall and buccal concavity may cause buccal perforation, dehiscence, or both in maxillary premolars. However, data on the restoration-driven principle to classify the maxillary premolar region are lacking. PURPOSE: The purpose of this clinical study was to investigate the occurrence of labial bone perforation and implantation into the maxillary sinus between various tooth-alveolar classifications with respect to the crown axis in maxillary premolars. MATERIAL AND METHODS: Cone beam computed tomography images of 399 participants (1596 teeth) were analyzed to determine the probability of labial bone perforation and implantation into the maxillary sinus when associated with variables that included tooth position and tooth-alveolar classification. RESULTS: The morphology in the maxillary premolars was classified as straight, oblique, or boot-shaped. The first premolars were 62.3% straight, 37.0% oblique, and 0.8% boot-shaped, and labial bone perforation occurred in 4.2% (21 of 497) of the straight, 54.2% (160 of 295) of the oblique, and 83.3% (5 of 6) of the boot-shaped first premolars when the virtual implant was 3.5×10 mm. When the virtual tapered implant was 4.3×10 mm, labial bone perforation occurred in 8.5% (42 of 497) of the straight, 68.5% (202 of 295) of the oblique, and 83.3% (5 of 6) of the boot-shaped first premolars. The second premolars were 92.4% straight, 7.5% oblique, and 0.1% boot-shaped, and labial bone perforation occurred in 0.5% (4 of 737) of the straight, 33.3% (20 of 60) of the oblique, and 0% (0 of 1) of the boot-shaped, respectively, when the virtual tapered implant was 3.5×10 mm; and labial bone perforation occurred in 1.3% (10/737) of the straight, 53.3% (32/60) of the oblique, and 100% (1/1) of the boot-shaped second premolars when the virtual tapered implant was 4.3×10 mm. CONCLUSIONS: When an implant is placed in the long axis of a maxillary premolar, the tooth position and tooth-alveolar classification should be considered when assessing the risk of labial bone perforation. Attention should be paid to the implant direction, diameter, and length in the oblique and boot-shaped maxillary premolars.

Factors impacting new bone formation in transcrestal sinus floor elevation followed by implant placement: a cross-sectional study.

OBJECTIVES: This study aimed to evaluate factors related to new bone formation (NBF) following simultaneous implant placement with transcrestal sinus floor elevation (TSFE). MATERIALS AND METHODS: Between 2008 and 2020, 357 implants (276 patients) were placed with TSFE. Clinical and radiographic examinations were performed at the preoperative, postoperative, restoration, and follow-up stages. Marginal bone loss, during healing, and the survival rate were retrospectively analyzed. RESULTS: Implant protrusion lengths (IPL: 3-5 mm) significantly influenced NBF during the healing period (P-value = 0.026, Odds Ratio = 1.15, 95% confidence interval = 1.02- 1.30). Bone grafting was correlated with NBF (P-value = 0.001). The distance between the implant and lateral wall of the sinus (mesial: P-value = 0.041, distal: P-value = 0.019, buccal: P-value = 0.032, lingual: P-value = 0.043) and angle between the implant and sinus floor significantly influenced NBF in four directions (mesial: P-value = 0.041, distal: P-value = 0.02, buccal: P-value = 0.047, lingual: P-value = 0.005). Implant shape (cylindrical or conical), perforations, smoking, and diabetes did not significantly affect NBF during the healing period (P > 0.05). CONCLUSION: Increasing the distance and angle between the implant and lateral wall of the sinus floor corresponded with reduced NBF. IPL may be an important factor that should be considered. CLINICAL RELEVANCE: Our study analyzed new bone formation following transcrestal sinus floor elevation among patients who underwent this procedure with simultaneous implant placement, several factors (including angle and distance between sinus and lateral wall and implant protrusion length) were included in our study.

Influence of bone anatomical morphology of mandibular molars on dental implant based on CBCT.

BACKGROUND: To apply CBCT to investigate the anatomical relationship between the mandibular molar and alveolar bone, aimed to provide clinical guidelines for the design of implant restoration. METHODS: 201 CBCT data were reevaluated to measure height of the alveolar process (EF), width of the alveolar process (GH), width of the basal bone (IJ), the angle between the long axis of the first molar and the alveolar bone (∠a) and the angle between the long axis of the alveolar bone and basal bone (∠b). The angle and width were measured to determine the implant-prosthodontic classification of the morphology in the left lower first molar (36) and right lower first molar (46). All measurements were performed on the improved cross-sectional images. RESULTS: EF, GH and IJ were measured as (10.83 ± 1.31) mm, (13.93 ± 2.00) mm and (12.68 ± 1.96) mm for 36, respectively; and (10.87 ± 1.24) mm, (13.86 ± 1.93) mm and (12.60 ± 1.90) mm for 46, respectively. No statistical significance was observed in EF, GH, IJ, ∠a and ∠b between 36 and 46 (all P > 0.05). The morphology was divided into three categories including the straight (68.7-69.2%), oblique (19.9-20.4%) and concave types (11%). Each type was consisted of two subcategories. CONCLUSIONS: The proposed classification could provide evidence for appropriate selection and direction design of the mandibular molar implant in clinical. The concave type was the most difficult to implant with the highest risk of lingual perforation. The implant length, width, direction required more attention.

Two-stage transcrestal sinus floor elevation-insight into replantation: Six case reports.

BACKGROUND: Transcrestal sinus floor elevation (TSFE) has been widely used in the oral clinic when the residual bone height (RBH) exceeds 5 mm. However, when there is insufficient RBH in the posterior maxilla, two-stage TSFE may be an option. CASE SUMMARY: This article introduces the concept of two-stage TSFE. Six patients had osseointegration failure after TSFE. For the first-stage surgery, we restricted the vertical bone augmentation as much as possible. At the second-stage surgery, the increased RBH was 3.28 ± 1.55 mm, which was beneficial for surgery. Five implants functioned successfully on schedule, but one implant failed again during the healing period. A third surgery was performed, and the implant functioned successfully. CONCLUSION: When RBH was less than 5 mm, two or more procedures of TSFE might result in a higher RBH.

The clinical accuracy of the implant digital surgical guide: A meta-analysis.

PURPOSE: To systematically evaluate the accuracy of clinical applications of digital guides. METHODS: First, PubMed and Embase databases were searched using the PICO standard. Eligible articles were included. Second, the eligible articles were classified according to the different types. Next, the NOS and ROB2 as evaluation indicators were used to evaluate the bias of those included articles. Finally, sensitive factors were excluded through the outcomes and data analyses were retrieved. RESULTS: More than 1,562 articles were retrieved, and 38 in vivo research documents were systematically analyzed after screening according to the inclusion criteria, which mainly listed three aspects of the coronal, apical, and angular implant data, and integrated the same type of articles in the study. To test its heterogeneity, the P-values of those articles included in the analysis were all less than 0.05. Finally, in the comparison between the guide group and the free-hand group after excluding sensitive factors, the standardized mean difference (Std.MD) of the angle was 1.26 (95% CI 1.06, 1.47), the Std.MD of the apical point was 1.38 (95% CI 1.12, 1.63), and the Std.MD of the coronal point was 0.98 (95% CI 0.66, 1.29). Comparing the maxillary and mandibular groups after excluding sensitive factors, the Std.MD of the coronal point was -0.31 (95% CI -0.52, -0.09), the Std.MD of the apical point was -0.15 (95% CI -0.34, 0.03), and the Std.MD of the angle is -0.23 (95% CI -0.46, 0.01). Comparison between the smoking group and the nonsmoking group, and between the flap group and the flapless group showed that there was not enough evidence to make a reliable assessment. CLINICAL SIGNIFICANCE: Compared with free-hand operation, a digital guide is more accurate in the apex, the coronal point and the angle, and the accuracy in the angle was very high. The difference in accuracy between the maxillary and mandibular groups was not statistically significant. Other factors such as smoking habit and flap need more clinical data.