3D extraoral morphometric changes after implant surgery: an exploratory pilot study using stereophotogrammetry.

OBJECTIVE: This pilot study aimed to evaluate, for the first time, the changes in facial tissues following the placement of a single dental implant. METHOD AND MATERIALS: Patients were scanned with a 3D facial scanner (3dMD) before implant surgery, immediately after surgery (T1), at 7 days postoperatively (T2), and at the impression stage (T3). Acquired images were processed using the 3dMDvultus (3dMD) software program and volume differences and linear depth measurements were calculated to determine the morphometric changes over time. A total of 11 patients were included in the analyses. Descriptive statistics were employed to analyze the data. RESULTS: The volumetric changes and maximum depth differences indicated an initial increase, followed by a progressive decrease in tissue volume after implant placement in the area of the surgery. The volume change values ranged between 2.5 and 3.9 cm3 for T1, whereas for T2, the volume change decreased to a range of 0.8 to 1.8 cm3. Maximum depth differences ranged between 2.06 and 2.80 mm in the soft tissues immediately after the implant surgery and reduced to around 2.01 to 0.55 mm at the impression stage. The amount of painkiller used was not related to the magnitude of linear depth measurements at any assessed time point. CONCLUSION: There was a longitudinal decrease in soft tissue volume and depth difference in extraoral soft tissues in the region of implant placement after surgery up to 6 weeks. The use of a facial scanner is a promising noninvasive method to monitor 3D morphometric changes after implant surgery.

Diagnosis of pathological speech with streamlined features for long short-term memory learning.

BACKGROUND: Pathological speech diagnosis is crucial for identifying and treating various speech disorders. Accurate diagnosis aids in developing targeted intervention strategies, improving patients' communication abilities, and enhancing their overall quality of life. With the rising incidence of speech-related conditions globally, including oral health, the need for efficient and reliable diagnostic tools has become paramount, emphasizing the significance of advanced research in this field. METHODS: This paper introduces novel features for deep learning in the analysis of short voice signals. It proposes the incorporation of time-space and time-frequency features to accurately discern between two distinct groups: Individuals exhibiting normal vocal patterns and those manifesting pathological voice conditions. These advancements aim to enhance the precision and reliability of diagnostic procedures, paving the way for more targeted treatment approaches. RESULTS: Utilizing a publicly available voice database, this study carried out training and validation using long short-term memory (LSTM) networks learning on the combined features, along with a data balancing strategy. The proposed approach yielded promising performance metrics: 90% accuracy, 93% sensitivity, 87% specificity, 88% precision, an F1 score of 0.90, and an area under the receiver operating characteristic curve of 0.96. The results surpassed those obtained by the networks trained using wavelet-time scattering coefficients, as well as several algorithms trained with alternative feature types. CONCLUSIONS: The incorporation of time-frequency and time-space features extracted from short segments of voice signals for LSTM learning demonstrates significant promise as an AI tool for the diagnosis of speech pathology. The proposed approach has the potential to enhance the accuracy and allow for real-time pathological speech assessment, thereby facilitating more targeted and effective therapeutic interventions.

An investigation into the cutting efficiency of a novel degradable glass as an alternative to alumina powder in air abrasion cutting of enamel.

OBJECTIVES: To develop and test the cutting efficiency of a novel degradable glass as an alternative media to alumina powder for air abrasion. MATERIALS AND METHODS: A zinc-based glass (QMZK2) was designed, produced, and evaluated with a multi-modality imaging analysis. The glass dissolution study was carried out in three acids, using ICP-OES (inductively coupled plasma optical emission spectroscopy) at 5 different time points: 2.5, 5, 10, 60, and 240 min. The cutting efficiency of both materials was tested under the same parameters on slabs of elephant enamel. A stained fissure of a molar tooth was air abraded with the glass and evaluated with X-ray micro-tomography before and after air abrasion. RESULTS: The particle size distribution of the glass was similar to that of alumina 53 µm but with a slightly greater dispersion of particle size. The shape of the particles was angular, appropriate for cutting purposes. The dissolution study showed that the glass dissolved rapidly in acidic conditions at all time points. Between the two variables, pressure and powder flow, pressure was found to influence the cutting speed to a greater extent than powder flow. CONCLUSIONS: Alumina powder was found to perform significantly better in 4 of the 9 conditions tested on elephant enamel, QMZK2 in one, and no significant differences were found for the rest of the 4 conditions. The QMZK2 seems to offer promising results as an alternative material to alumina. CLINICAL RELEVANCE: QMZK2 glass has the potential for replacing aluminum oxide as a degradable material in air abrasion technology.

Royal London space analysis: plaster versus digital model assessment.

Aim: With the advent of digital study models, the importance of being able to evaluate space requirements becomes valuable to treatment planning and the justification for any required extraction pattern. This study was undertaken to compare the validity and reliability of the Royal London space analysis (RLSA) undertaken on plaster as compared with digital models. Materials and methods: A pilot study (n = 5) was undertaken on plaster and digital models to evaluate the feasibility of digital space planning. This also helped to determine the sample size calculation and as a result, 30 sets of study models with specified inclusion criteria were selected. All five components of the RLSA, namely: crowding; depth of occlusal curve; arch expansion/contraction; incisor antero-posterior advancement and inclination (assessed from the pre-treatment lateral cephalogram) were accounted for in relation to both model types. The plaster models served as the gold standard. Intra-operator measurement error (reliability) was evaluated along with a direct comparison of the measured digital values (validity) with the plaster models. Results: The measurement error or coefficient of repeatability was comparable for plaster and digital space analyses and ranged from 0.66 to 0.95mm. No difference was found between the space analysis performed in either the upper or lower dental arch. Hence, the null hypothesis was accepted. The digital model measurements were consistently larger, albeit by a relatively small amount, than the plaster models (0.35mm upper arch and 0.32mm lower arch). Conclusion: No difference was detected in the RLSA when performed using either plaster or digital models. Thus, digital space analysis provides a valid and reproducible alternative method in the new era of digital records.

The reliability of thermoform retainers: a laboratory-based comparative study.

AIM: Despite a very significant increase in the use of thermoform retainers, within orthodontics, to date, there is no evidence regarding the quality of fit between the dental cast and retainer. The current study aims to compare the fit of different thermoform retainer materials, under laboratory standardized conditions. MATERIALS AND METHODS: A prospective, laboratory-based study design was adopted to compare the fit of four different commercially available thermoform retainer materials. A master dental cast was fabricated in dental stone, to which three and five specific reference points were located on the central incisors and upper first molars, respectively. The master cast was then duplicated to produce a total of 40 such dental casts. The performance of the following four test materials was investigated: ACE, C+ (Raintree Essix Glenroe), True Tain (True Tain Inc.), and Iconic Clear (DB Orthodontics). For each material, 10 thermoform retainers were fabricated within the dental laboratory. Subsequent scanning and analysing of the casts and thermoform retainers was performed in a dedicated area, using the co-ordinate measuring machine, in order to calculate their respective fit at the incisor and first molar regions. RESULTS: At all eight recorded landmark points, the mean values for the following thermoform materials: ACE, True Tain, and Iconic Clear, a similar trend was observed. At all eight points, there was a significant difference between the performance of the four different materials (P < 0.001), with the greatest difference observed in the mean values in relation to material C+. CONCLUSION: Statistically significant differences were observed in the fit behaviour of all four thermoform materials being tested.

Taper of full-veneer crown preparations by dental students at the University of the West Indies.

PURPOSE: The ideal taper recommended for a full-veneer crown is 4° to 14°, but this is very difficult to achieve clinically, and studies on taper achieved by dental students have found mean taper measurements ranging from 11° to 27°. The objective of this study was to examine and compare the taper of teeth prepared for full-veneer crowns by dental students on typodonts in the laboratory and on patients, and also to compare the results with those of other dental schools. MATERIALS AND METHODS: Preparations were scanned by specialized metrology equipment that gave the taper of the preparation in a buccolingual (BL) and mesiodistal (MD) plane. RESULTS: No undercut was detected on any of the laboratory specimens; however, 12.5% of clinical specimens were undercut. The mean taper of the laboratory anterior specimens were 26.7° BL and 14.9° MD, and the laboratory posterior specimens were 18.2° BL and 14.2° MD. The mean taper of the clinical anteriors were 31.6° BL and 16.8° MD, and the clinical posteriors were 16.8° BL and 22.4° MD. CONCLUSIONS: This study shows that although the taper achieved by dental students in the University of the West Indies when preparing teeth for full-veneer crowns was outside the ideal range of 4° to 14°, it is comparable to those achieved by dental students in other schools.

Consistency of labial finish line preparation for metal ceramic crowns: an investigation of a new bur.

PURPOSE: Previous studies have reported on the difficulties inherent in preparing the labial aspect of teeth for metal ceramic crowns with consistency and also the implications for the definitive restoration of underprepared and overangled finish lines. In this study, a bur designed to prepare a 1.2-mm deep chamfer was tested and compared with two other bur kits. MATERIALS AND METHODS: Seventy-two teeth were prepared to receive metal ceramic crowns in vitro by students using one of the two bur kits or the new bur. Using a coordinate measuring machine (CMM), replicas of the prepared teeth were scanned in the mid-labial plane, and shoulder width and cavosurface angles were measured. RESULTS: The new bur produced preparations with a mean shoulder width and cavosurface angle of 1.146 +/- 0.241 mm and 108 +/- 11 degrees, respectively, compared with 0.626 +/- 0.234 mm and 128 +/- 14 degrees produced by a commercially available standardized crown cutting bur system and 0.626 +/- 0.218 mm and 124 +/- 15 degrees produced by the bur kit in use at our center at the time of the study. These differences were statistically significant at the 5% level, using Tukey's comparison of means. CONCLUSIONS: Teeth prepared by the new bur had wider shoulders and lower cavosurface angles than teeth prepared either with a standardized crown cutting system or locally selected bur kit. The quality of labial preparations produced by the new bur in terms of closeness to the postulated "ideal" width and angulation warrants further investigation.

Abutment taper of full cast crown preparations by dental students in the UWI School of Dentistry.

Retention of crowns has been shown to be inversely proportional to taper. The objective of this study was to compare the abutment taper of teeth prepared for full veneer crowns by students at the UWI School of Dentistry with those of other dental schools. Twenty five dies were scanned by a Co-ordinate Measuring Machine (CMM) and the mean taper and standard deviations were found to be 20.3 +/- 11.3 degrees mesio-distally and 18.3 +/- 8.5 degrees bucco-lingually. This study shows that the taper achieved by dental students at the UWI School of Dentistry preparing teeth for full veneer crowns is comparable to those achieved by other dental students in the US, UK, Europe and Japan.

Dentin exposure in tooth preparations for porcelain veneers: a pilot study.

STATEMENT OF PROBLEM: The various clinical techniques available for even reduction of a tooth surface to receive a porcelain veneer restoration do not produce a consistently even conservative reduction. In addition, it is not known which technique is most conservative of enamel. PURPOSE: The purpose of this pilot study was to assess the effectiveness of 3 clinical techniques, namely, dimple, depth groove, and freehand, in producing an intraenamel preparation. The relation between overpreparation beyond the commonly accepted depth of preparation of 0.5 mm and dentin exposure was also examined. MATERIAL AND METHODS: A single operator prepared 3 groups of 5 extracted maxillary central incisors to a depth of 0.5 mm using dimple, depth-groove, and freehand methods of tooth preparation. The prepared teeth were scanned using an x-ray microtomography scanner. The reconstructed images were studied using software that provided a volume-rendering routine so that, by choosing suitable x-ray linear attenuation coefficient thresholds, enamel (2.78 cm(-1) at 40 keV) and dentin (1.63 cm(-1) at 40 keV) surfaces could be viewed. The percentage area of enamel conserved was analyzed from these images. Coordinate metrology was used to produce color-coded images depicting the depth of preparation. The Kruskal-Wallis test was used to determine the statistical significance (alpha=.05) in the difference between the mean percentage area of enamel conserved in the 3 technique groups. The coordinate metrology and x-ray microtomography images were visually compared to study the correlation between overpreparation and dentin exposure. RESULTS: The Kruskal-Wallis test did not demonstrate significant difference (P=.07) between the 3 techniques in conserving enamel. However, the dimple technique showed a greater trend to retaining a larger mean percentage area of enamel (77.5% +/- 14.2) compared to depth-groove (50.1% +/- 17.5) and freehand (76.8% +/- 24.4) techniques. Preparation depth in the range of 0.4 to 0.6 mm was largely seen to be intraenamel, except in the cervical region. CONCLUSION: Within the limitations of this pilot study, the 3 different techniques tested did not differ significantly in conserving enamel.